Patent Publication Number: US-9416763-B2

Title: After-treatment apparatus for exhaust gas in a combustion chamber

Description:
TECHNICAL FIELD 
     This invention belongs to the technical field of the internal combustion engine and relates to an after-treatment apparatus for exhaust gas in an internal combustion engine with an intake-exhaust system. 
     BACKGROUND OF THE INVENTION 
     The gas in an internal combustion engine contains gas state components, PM (Particulate Matter, can say Particulate), unburned hydrocarbons (UBS or HC), carbon monoxide (CO), nitric oxides (NO X ), carbon dioxide (CO 2 ), water vapor (H 2 O), oxygen (O 2 ), and nitrogen (N 2 ) and so on. PM in exhaust gas from, for example diesel among internal combustion engines, points solid or liquid particles larger than 10 μm. The solid or liquid particles include soot consisting of carbonaceous, combustible organic fraction that consists high-boiling-point carbon hydride and sulfate moieties. 
     For example, Patent Document 1 discloses a discharge type exhaust gas control apparatus that includes a diesel particulate filter and a plasma generator as an exhaust gas control apparatus for eliminating these components from exhaust gas. The diesel particulate filter is installed in the exhaust passage. The plasma generator is combined with the diesel particulate filter or installed upstream of the filter. The plasma generator stably supplies NO 2  and active substances (active oxygen), which are needed for the combustion (oxidation) of exhaust particulates collected by the particulate filter, in the discharge-type exhaust gas control apparatus. 
     Patent Document 2 discloses an exhaust gas control apparatus comprising an after-treatment device which cleans aeration exhaust gas in the middle of exhaust pipe from an internal combustion engine. The exhaust gas control apparatus includes a plasma generator, flow-through oxidation catalyst, a means of adding fuel and increasing the temperature. The plasma generator generates plasma by discharging into the exhaust gas above the after-treatment device. The style oxidation catalyst is installed before the plasma generator. Fuel is added to the exhaust gas before the oxidation catalyst by the means of adding fuel. The means of increasing the temperature elevates temperature of exhaust gas until occurring oxidation, on the oxidation catalyst, of fuel added by the means of adding fuel. Using this apparatus to energize exhaust gas with the discharge of the plasma generator into the exhaust gas, the unburned carbon hydride is converted into active radicals, oxygen into ozone, NO into NO 2 . These exhaust gas components becomes active, resulting in a greater exhaust purification effect than with existing after-treatment devices from low temperature area. 
     Patent Document 3 discloses an after-treatment method for exhaust gas and apparatus for it. In this apparatus, an after-treatment unit for exhaust gas, a particulate filter, is placed in the exhaust pipe and an oxidation reactor, a plasma reactor, is installed upstream from it. When the oxidation reactor generates non-heat plasma in the exhaust gas flowing through the oxidation reactor, oxidants are generated from the exhaust gas components. As the result, soot is incinerated with the oxidants in the particulate filter, and reproduced. 
     Patent Document 4 discloses an exhaust gas purification apparatus. It contains a filter that catches particulate matter, an absorbent that absorb components of the exhaust gas, and a plasma generator that generate plasma with applied voltage, in exhaust smoke path of the internal combustion engine. The exhaust gas purification apparatus eliminates the accumulated particles on the filter and absorbent material or the exhaust gas components at normal temperature below the particulate ignition temperature. It enables the removal of harmful substances and particulates contained in internal combustion engine gases, such as diesel exhaust gas, at exhaust temperatures below 150° C. 
     Patent Document 5 discloses an exhaust purification apparatus comprising a means of purification and a means of forming plasma. The purifier is installed in the exhaust path of the internal combustion engine, and contains NOx-absorbing materials and/or a particle filter. The means of forming plasma is installed in the exhaust path. The exhaust purification apparatus comprises a means of detecting oxygen density and controlling means. The means of detecting oxygen density detects oxygen density in exhaust gas. The controlling means results in the purification of the exhaust gas due to the means of purification when the oxygen density on the means of detecting oxygen density, decreasing the oxygen density in the exhaust gas while simultaneously driving the means of forming plasma when the amount of absorbed material exceeds a predetermined value. If applying this apparatus for stationary fuel system, such as steam generator and gas turbine, or transferring fuel system such as diesel automobile, the cost is lower than that of existing plasma processes because of un-necessity of firm power. Moreover it will be possible to remove NOx and soot at the same time effectively by plasma desorption at high density. 
     Patent Document 6 discloses a ways to reduce particle matter included in the exhaust gas from a lean-burn engine. In the ways to reduce particle matter, plasma is generated in the exhaust gas, includes particle matter, from lean-burn engine etc. As the result, several carbon dioxide and ozone are generated and the particle matter is oxidized by these carbon dioxide and ozone. 
     Patent Document 7 discloses an exhaust gas breaking apparatus. This exhaust gas breaking apparatus comprises a microwave oscillation device, microwave resonant cavity, microwave radiation means, and ignition means using plasma. The microwave oscillation device generates certain microwave marginal zone. The microwave resonant cavity resonates part of the microwave zone. The microwave radiation means radiates microwave to the microwave resonant cavity. The ignition means forms gas plasma by partly discharging in the gas inside said microwave resonant cavity. Said microwave radiation mean is arranged in circumferential direction in periphery of flow path where exhaust gas flows. Said microwave radiation mean is a microwave radiating antenna with a configuration and size such that a strong electric field place, where plasma generating area generated with microwave becomes the same in the passage section, is generated. Applying this apparatus, carbon-carbon and carbon-hydrogen bonds are broken by the strong oxidation power of ozone and OH radicals along with plasma generation in exhaust gas, including unborn gas, soot, and NOx in combustion/reactive room. As a result, it becomes stabilizes harmless oxide such as NO 2  and CO 2  or carbon via the chemical reaction involving oxidation and OH radicals. The exhaust gas components are rendered harmless. 
     [Patent Document 1] Japanese Patent Application Laid-open Publication No. 2002-276333 
     [Patent Document 2] Japanese Patent Application Laid-open Publication No. 2004-353596 
     [Patent Document 3] Japanese Patent Application Laid-open Publication No. 2005-502823 
     [Patent Document 4] Japanese Patent Application Laid-open Publication No. 2004-293522 
     [Patent Document 5] Japanese Patent Application Laid-open Publication No. 2006-132483 
     [Patent Document 6] Japanese Patent Application Laid-open Publication No. 2004-169643 
     [Patent Document 7] Japanese Patent Application Laid-open Publication No. 2007-113570 
     SUMMARY OF THE INVENTION 
     In the case of technique in Patent Documents 1 through 6, a particulate filter or other exhaust gas depuration apparatus is installed in much lower place from the portion of the exhaust passage formed in the cylinder head of an internal combustion engine in the light of the layout. Therefore, the temperature of the exhaust gas decreases before reaching the exhaust depuration apparatus from the combustion chamber. For that point, it is thought to clean the exhaust gas effectively by elevating the temperature in the exhaust depuration apparatus so as to promote oxidation reaction etc. of the exhaust gas components in the exhaust gas depuration. However, a rich air-to-fuel ratio or excessive afterburning downstream of the combustion chamber will get terrible mileage of the internal combustion engine. 
     The inventor of the present invention extrapolated the mechanism of combustion promotion in the internal combustion engine which is disclosed in Patent Document 7, and obtained a constant finding about the mechanism. In this mechanism, a small amount of plasma is discharged firstly. The plasma is irradiated with microwaves for a given period of time, so that the amount of plasma increases. Thus a large amount of OH radicals and ozone is generated from moisture in the air-fuel mixture within a short period of time, promoting an air-fuel mixture reaction. Furthermore, by using a large amount of OH radicals and ozone property, it will be able to promote oxidation reaction of the exhaust gas components. 
     In the view of the foregoing, the present invention has been achieved. An object of the invention is to provide an after-treatment apparatus to clean the exhaust gas highly efficiently. This after-treatment apparatus uses the combustion camber right after explosion stroke as a reactor. In the reactor, the combustion-promoting mechanism obtained by generating a large amount of OH radicals and ozone with plasma is applied. The oxidation reaction etc. of the exhaust gas components is promoted by providing high temperature exhaust gas with a large amount of OH radicals and ozone. As a result, a highly efficient exhaust gas cleanup is achieved. 
     The present invention is an after-treatment apparatus for exhaust gas in a combustion chamber, which is installed in an internal combustion engine where a piston fits into a cylinder penetrating a cylinder block to reciprocate freely, a cylinder head is assembled to the anti-crankcase side of the cylinder block with a gasket between it and the cylinder block, an intake port opening on the cylinder head is opened and closed with an intake valve, an exhaust port opening on the cylinder head is opened and closed with an exhaust valve, the combustion chamber is formed by these parts, the after-treatment apparatus comprises, a discharge device with an electrode exposed to the combustion chamber and installed in at least one of the parts constituting the combustion chamber, an antenna installed in at least one of the parts constituting the combustion chamber, so as to radiate electromagnetic waves into the combustion chamber, an electromagnetic wave transmission line installed in at least one of the parts constituting the combustion chamber with one end connected to the antenna and the other end covered with an insulator or dielectric and extending to a portion, in at least one of the parts constituting the combustion chamber, distant from the combustion chamber, and an electromagnetic wave generator for feeding electromagnetic waves to the electromagnetic wave transmission line, the after-treatment apparatus is configured such that discharge is generated with the electrode of the discharge device and the electromagnetic waves fed from the electromagnetic wave generator through the electromagnetic wave transmission line are radiated from the antenna, while the exhaust gas remains in the combustion chamber after the exhaust gas is produced during the explosion stroke. 
     In the actuation of the internal combustion engine, discharge is generated at the electrode of the discharge device and the electromagnetic waves fed from the electromagnetic wave generator through the electromagnetic wave transmission line are radiated from the antenna. Therefore, the plasma is generated near the electrode. This plasma receives energy of an electromagnetic waves (electromagnetic wave pulse) supplied from the antenna for a given period of time. As a result, the plasma generates a large amount of OH radicals and ozone to promote the oxidation reaction etc. of the exhaust gas components. In fact electrons near the electrode are accelerated, fly out of the plasma area, and collide with gas such as air or the air-fuel mixture in surrounding area of said plasma. The gas in the surrounding area is ionized by these collisions and becomes plasma. Electrons also exist in the newly formed plasma. These also are accelerated by the electromagnetic wave pulse and collide with surrounding gas. The gas ionizes like an avalanche and floating electrons are produced in the surrounding area by chains of these electron acceleration and collision with electron and gas inside plasma. These phenomena spread to the area around discharge plasma in sequence, then the surrounding area get into plasma state. In the result of the phenomena as mentioned above it, the volume of plasma increases. Then the electrons recombine rather than dissociate at the time when the electromagnetic wave pulse radiation is stopped. As a result, the electron density decreases, and the volume of plasma decreases as well. The plasma disappears when the electron recombination is completed. A large amount of OH radicals and ozone is generated from moisture in the gas mixture as a result of a large amount of the generated plasma, promoting the oxidation reaction etc. of the exhaust gas components. 
     In that case, oxidation reaction etc. is initiated in the combustion chamber as a reactor while exhaust gas remains in the combustion chamber after the exhaust gas is produced during explosion stroke. The high temperature of the exhaust gas also promotes the oxidation reactions, which increases cleanup efficiency in combination with the oxidation reaction etc. obtained by generating a large amount of OH radicals and ozone with plasma. Therefore, it is not necessary to use a rich air-to-fuel ratio or afterburning downstream of the combustion chamber, which would prevent the mileage reduction of the internal combustion engine. 
     In addition, until the intake valve opens the intake port or the exhaust valve opens the exhaust port after generation exhaust gas by explosion stroke, the electromagnetic waves scattering from the combustion chamber to outside is prevented. Moreover, the back face of the intake valve or the exhaust valve prevents some electromagnetic waves from scattering from the combustion chamber to the intake port or the exhaust port after the intake valve opens the intake port or the exhaust valve opens the exhaust port. Therefore, closed space of the combustion chamber or space according to it becomes a reactor, where the oxidation reaction etc. of the exhaust gas components is stably initiated. 
     The after-treatment apparatus of the present invention may be applicable for which the after-treatment apparatus is configured such that discharge is generated with the electrode of the discharge device and the electromagnetic waves fed from the electromagnetic wave generator through the electromagnetic wave transmission line are radiated from an antenna, from the time when exhaust gas is produced at the explosion stroke to the time when the intake valve opens the intake port or the exhaust valve opens the exhaust port. 
     This makes it possible that the intake valve and exhaust valve prevents electromagnetic waves from scattering from the combustion chamber to outside. Therefore, closed space of the combustion chamber becomes a reactor, where the oxidation reaction etc. of the exhaust gas components is stably initiated. 
     The after-treatment apparatus of the present invention may comprise a crank angle detector for detecting the crank angle of the crank shaft, and a controller for controlling the discharge device and electromagnetic wave generator once they receive a signal from the crank angle detector. 
     This makes it possible that discharge at the electrode, and the radiation of the electromagnetic waves from the antenna, are controlled according to the crank angle. 
     The after-treatment apparatus of the present invention may be applicable for which the electrode is located close to a portion that the electric field intensity generated by the electromagnetic waves strengthen in the antenna when the electromagnetic waves are fed into the antenna. 
     This makes it possible that the electrical field intensity, due to the electromagnetic waves radiated from said portion of the antenna, is stronger than the electrical field intensity of the surrounding electromagnetic waves. Therefore, the energy of the electromagnetic wave pulse is intensively supplied to the plasma generated by discharge at the electrode. As a result, a large amount of OH radicals and ozone is efficiently generated, further promoting the oxidation reaction etc. of the exhaust gas components in the area centered at the electrode. When there are multiple areas of the antenna with strong electrical field intensity, the oxidation reaction etc. of the exhaust gas components at multiple areas of the combustion chamber is further promoted upon the portion approaching to the electrode. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a vertical cross-sectional view of combustion chamber in an internal combustion engine with the after-treatment apparatus for exhaust gas in a combustion chamber in the first embodiment of the present invention; 
         FIG. 2  shows an enlarged cross sectional view of the cylinder block in an internal combustion engine with the after-treatment apparatus for exhaust gas in a combustion chamber in the first embodiment of the present invention, sectioned at the position of the electromagnetic wave transmission line; 
         FIG. 3  shows an enlarged cross sectional view of the cylinder block in an internal combustion engine with the after-treatment apparatus for exhaust gas in a combustion chamber in the first embodiment of the present invention, sectioned at the position of the antenna; 
         FIG. 4  shows an explanation chart which explains the operation of the after-treatment apparatus for exhaust gas in a combustion chamber in the first embodiment of the present invention; 
         FIG. 5  shows an explanation chart which explains the another operation of the after-treatment apparatus for exhaust gas in a combustion chamber in the first embodiment of the present invention; 
         FIG. 6  shows a vertical cross-sectional view of combustion chamber in an internal combustion engine with the gasket used by the after-treatment apparatus for exhaust gas in the second embodiment of the present invention; 
         FIG. 7  shows a diagrammatic perspective view of the gasket used by the after-treatment apparatus for exhaust gas in the second embodiment of the present invention; 
         FIG. 8  shows a cross-sectional view of near one opening of the gasket, along the surface of it seen from thickness direction, used by the after-treatment apparatus for exhaust gas in the second embodiment of the present invention; 
         FIG. 9  shows an enlarged vertical cross-sectional view of the gasket, along the discharge line, used by the after-treatment apparatus for exhaust gas in the second embodiment of the present invention; 
         FIG. 10  shows an enlarged vertical cross-sectional view of the gasket, along the electromagnetic wave transmission line, used by the after-treatment apparatus for exhaust gas in the second embodiment of the present invention; 
         FIG. 11  shows a cross-sectional view of near one opening of the gasket, along the surface of it seen from thickness direction, used by the after-treatment apparatus for exhaust gas in the first modification of the second embodiment of the present invention; 
         FIG. 12  shows a cross-sectional view of near one opening of the gasket, along the surface of it seen from thickness direction, used by the after-treatment apparatus for exhaust gas in the second modification of the second embodiment of the present invention; 
         FIG. 13  shows a cross-sectional view of near one opening of the gasket, along the surface of it seen from thickness direction, used by the after-treatment apparatus for exhaust gas in the third modification of the second embodiment of the present invention; 
         FIG. 14  shows an enlarged vertical cross-sectional view of the gasket, along the electromagnetic wave transmission line, used by the after-treatment apparatus for exhaust gas in the forth modification of the second embodiment of the present invention; 
         FIG. 15  shows a cross-sectional view of near one opening of the gasket, along the surface of it seen from thickness direction, used by the after-treatment apparatus for exhaust gas in the fifth modification of the second embodiment of the present invention; 
         FIG. 16  shows a vertical cross-sectional view of combustion chamber in an internal combustion engine with the after-treatment apparatus for exhaust gas in the third embodiment of the present invention; 
         FIG. 17  shows an enlarged vertical cross-sectional view of exhaust port in an internal combustion engine with the after-treatment apparatus for exhaust gas in the third embodiment of the present invention; 
         FIG. 18  shows an enlarged vertical cross-sectional view of exhaust valve used by the after-treatment apparatus for exhaust gas in the third embodiment of the present invention; 
         FIG. 19  shows an enlarged view of exhaust valve used by the after-treatment apparatus for exhaust gas in the third embodiment of the present invention, as seen from the valve face of the head; 
         FIG. 20  shows an enlarged vertical cross-sectional view of exhaust valve used by the after-treatment apparatus for exhaust gas in the third embodiment of the present invention; 
         FIG. 21  shows a vertical cross-sectional view of combustion chamber in an internal combustion engine with the after-treatment apparatus for exhaust gas in the forth embodiment of the present invention; 
         FIG. 22  shows an enlarged cross-section view of the cylinder block, along a surface seen from the direction of reciprocation of piston, in an internal combustion engine with the after-treatment apparatus for exhaust gas in the forth embodiment of the present invention; and 
         FIG. 23  shows an enlarged cross-section view of the cylinder block, along a surface seen from the direction of reciprocation of piston, in an internal combustion engine with the after-treatment apparatus for exhaust gas in the modification of the forth embodiment of the present invention. 
     
    
    
     DESCRIPTION OF REFERENCE CHARACTERS 
     
         
         
           
             E Internal combustion engine 
               100  Cylinder block 
               110  Cylinder 
               200  Piston 
               300  Cylinder head 
               320  Exhaust port 
               321  Opening 
               340  Guide hole 
               350  Valve guide mounted hole 
               360  Valve guide 
               400  Combustion chambers 
               520  Exhaust valve 
               521  Valve stem 
               521   a  Basic portion 
               521   b  Periphery portion 
               522  Valve head 
               522   a  Basic portion 
               522   b  Valve face 
               760 , 810  Discharge device 
               762 , 811 , 812 , 813  Electrode 
               770 , 820  Antenna 
               780 , 830  Electromagnetic wave transmission line 
               840  Electromagnetic wave generator 
               850  Dielectric member 
               860  Power-feeding member 
           
         
       
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, embodiments of the present invention will be described.  FIG. 1  shows the embodiment of the internal combustion engine E with the after-treatment apparatus for exhaust gas in a combustion chamber of the present invention. The present invention targets reciprocating engines. In this embodiment, engine E is a four-cycle gasoline engine. Item  100  is the cylinder block. Cylinder block  100  contains cylinder  110 , which has an approximately circular cross section. Cylinder  110  penetrates cylinder block  100 . Piston  200 , which has an approximately circular cross section corresponding to cylinder  110 , fits into cylinder  110  and reciprocates freely. Cylinder head  300  is assembled on the anti-crankcase side of cylinder block  110 . Cylinder head  300 , piston  200 , and cylinder  110  form combustion chamber  400 . Item  910  is a connecting rod, with one end connected to piston  200  and the other end connected to crankshaft  920 , which is the output shaft. Cylinder head  300  has intake port  310 , which is a component of the intake line, and exhaust port  320 , which is a component of the exhaust line. One end of intake port  310  connects to combustion chamber  400 ; the other end is open at the outside wall of cylinder head  300 . One end of intake port  310  is open at the wall of cylinder head  300  face to the cylinder  110 ; the other end is open at the outside wall of cylinder head  300 . One end of exhaust port  320  is open at the wall of cylinder head  300  face to the cylinder  110 ; the other end is open at the outside wall of cylinder head  300 . Cylinder head  300  has guide hole  330  that passes through intake port  310  to the outside wall of cylinder head  300 . Rod-shaped valve stem  511  of intake valve  510  fits into guide hole  330  and reciprocates freely. Umbrella-shaped valve head  512 , set at the end of valve stem  511 , opens and closes the combustion chamber side opening  311  of intake port  310  at a given timing by a valve open/close mechanism having a cam and so on (not shown in the figure). Cylinder head  300  has guide hole  340  that passes through exhaust port  320  to the outside wall of cylinder head  300 . Rod-shaped valve stem  521  of exhaust valve  520  fits into guide hole  340  and reciprocates freely. Umbrella-shaped valve head  522 , set at the end of valve stem  521 , opens and closes the combustion chamber side opening  321  of the exhaust port  320  at a given time by the valve open/close mechanism having cam and so on (not shown in the figure). Item  910  is a connecting rod, with one end connected to piston  200  and the other end connected to crankshaft  920 , which is the output shaft. Moreover, cylinder block  100 , piston  200 , gasket  700 , cylinder head  300 , intake valve  510 , and exhaust valve  520  form combustion chamber  400 . Item  600  is a spark plug installed in cylinder head  300  to expose the electrode to combustion chamber  400 . Spark plug  600  discharges at the electrodes when piston  200  is near top dead center. Therefore, four strokes (intake, compression, combustion of mixture, and exhaust of exhaust gas) occur while piston  200  reciprocates between top dead center and bottom dead center twice. However, this embodiment does not restrict the interpretation of the internal combustion engine targeted by the present invention. The present invention is also suitable for use with two-stroke internal combustion engines and diesel engines. Target gasoline engines include direct-injection gasoline engines, which create a mixture inside the combustion chamber to inject fuel into the intake air. Target diesel engines include direct-injection diesel engines, which inject fuel into the combustion chamber directly, and divided-chamber diesel engines, which inject fuel into the divided chamber. Internal combustion engine E in this embodiment has four cylinders, but this does not restrict number of cylinders of the internal combustion engine targeted by the present invention. The internal combustion engine for this embodiment has two intake valves  510  and two exhaust valves  520 , but this does not restrict the number of intake or exhaust valves of the internal combustion engine targeted by the present invention. 
     The discharge device  810  with electrode  811  exposed to the combustion chamber  400  is installed in the cylinder block  100 , as shown in  FIGS. 1 and 2 . The wall of cylinder  110  in cylinder block  110  contains a hole that penetrates the wall from cylinder side to the outside wall. The first support  120  with tube-shaped is installed in this hole. This first support  120  is made from ceramics. Like this, the first support  120  may be made from dielectric, but it may be made from insulator. One end face of this first support  120  is the same level with the cylinder  110  wall. This first support  120  is exposed to cylinder  110 , and the other end of this first support  120  reaches the outside wall of cylinder block  100 . And, discharge device  810  is installed in the first support  120 . The discharge device  810  only has to be made from a conductor although it is made from the copper wire. A couple of discharge device  810  is buried in the first support  120 , and it goes though the first support  120 . The end face of each discharge device  810  is the same level with the wall of the cylinder  110 . The end face of each discharge device  810  exposes to cylinder  110  and composes electrode  811 . The other end of each discharge device  810  is extracted from the outside wall of cylinder block  100  to outside. In one of a pair discharge devices  810 , the end portion that exposed from the outside wall of cylinder block is connected to discharge voltage generator  950  which generates voltage for discharge. In another of a pair discharge devices  810 , the end portion that exposed from the outside wall of cylinder block is earthed. Here, the discharge voltage generator discharge  950  is DC 12V power supply, but it may be used for example piezo element or other device. When the discharge voltage generator  950  applies the voltage between a pair of discharge devices  810 , the discharge is generated between a pair of electrodes  811 . As a modification, the number of the discharge line, buried and passes thorough the first support, may be one. In this case, the discharge voltage generator is connected with the discharge line, and the voltage is applied with the discharge voltage generator between the discharge line and cylinder blocks which is the earth member. Then, the discharge is generated between the electrode of the discharge line and the cylinder block. In this embodiment, four discharge lines are installed, these are arranged so that their four electrodes are located at approximately equal intervals to the circumferential direction of cylinder  110 , as shown in  FIG. 2 . However, this after-treatment apparatus for exhaust gas requires only more than one discharge device installation, and number of discharge devices and its location are not cause of restrict interpretation by this embodiment. In this embodiment, part of discharge line  810  except the electrode and the electrode  811  are formed from the same material as one body. However, part of discharge line except the electrode and the electrode are formed separately and connected. Part of discharge line  760  except the electrode and the electrode are made from the different material. The spark plug can be used as a discharge device. The discharge device requires generating plasma by discharge regardless the size. 
     Antenna  820  is installed in cylinder block  100  to radiate the electromagnetic waves into combustion chamber  400 , as shown in  FIGS. 1 and 3 . The groove that dents in the direction where the radius of cylinder  110  expands and extends in circumferential direction of cylinder  110  is installed on the wall of cylinder  110  in cylinder block  100 . The second support  130  is installed in this groove, and it orbits in circumferential direction to be ring-shaped. This second support  130  is made from ceramics. Although the second support  130  could be formed from the dielectric substance, also could be formed from insulator. An inner side wall of second support  130  is at the same level with the cylinder  110  wall and it is exposed to cylinder  110 . And, antenna  820  is installed in the second support  130 . This antenna  820  is made from metal. This antenna  820  may be made from conductor or dielectric or insulator and so on. However, electromagnetic waves must be radiated from the antenna to the combustion chamber well upon supplying electromagnetic waves between the antenna and the earth member. This antenna  820  is bar-style, and has almost curved to a circular arc type along the wall of cylinder  110 . For example, the length of the antenna  820  is set to a quarter of wavelength in electromagnetic waves, standing wave is generated in the antenna  820 . Thus, electrical field strength at the end of antenna  820  becomes strong. For example, the length of the antenna  820  is set to a multiple of a quarter wavelengths of the electromagnetic waves so that standing waves are generated in the antenna  820 , increasing the electrical field at multiple points, where the anti-nodes of the standing waves are generated, in the antenna  820 . Here, antenna  820  is buried in the second support  130 . An inner surface of antenna  820  is the same level of the cylinder wall of  110  and is exposed to cylinder  110 . As shown in  FIG. 1 , the solid cross-section of antenna  820  is approximately rectangle for its entire length. Antenna  820  is exposed to cylinder  100  at one side on the circumference of circle or its entire length. However, antenna  820  of the after-treatment apparatus for exhaust gas of the present invention is not restricted to a rectangle cross-sectional shape. Antenna  820  may be completely buried in the second support. Additionally, the electrode  811  is located close to a portion that electric field intensity generated by the electromagnetic waves becomes strong in the antenna  820  when the electromagnetic waves are fed to the antenna  820 . In here, the end of antenna  820  and the electrode  811  are close to each other along the wall of combustion chamber  400  at specified intervals. Thus, when electromagnetic waves are supplied between antenna  820  and said earth cylinder block  100 , the electromagnetic waves are radiated from antenna  820  into combustion chamber  400 . For this embodiment, antenna  820  is a rod-shaped monopole antenna that is curved one. However, this does not restrict the type of antenna in the after-treatment apparatus for exhaust gas of the present invention. Therefore, antenna of the after-treatment apparatus for exhaust gas of the present invention may be dipole type, Yagi-Uda type, single wire type, loop type, phase difference feeder type, grounded type, ungrounded and perpendicular type, beam type, horizontal polarized omni-directional type, corner-reflector type, comb type or other type of linear antenna, microstrip type, planar inverted F type or other type of flat antenna, slot type, parabola type, horn type, horn reflector type, Cassegrain type or other type of solid antenna, Beverage type or other type of traveling-wave antenna, star EH type, bridge EH type or other type of EH antennas, bar type, small loop type or other type of magnetic antenna, or dielectric antenna. 
     Electromagnetic wave transmission line  830  is installed in cylinder block  100 . One of the electromagnetic wave transmission lines  830  is connected with the antenna  820 . The other end of electromagnetic wave transmission line  830  is covered with a dielectric, and extends to a portion of the cylinder block  100 , distant from the combustion chamber  400 . The wall of cylinder  110  in cylinder block  110  contains a hole that penetrates the wall from periphery side of second support  130  to the outside wall. The third support  140  with tube-shaped is installed in this hole. This third support  140  is made from ceramics. Like this, the third support  140  may be made from dielectric, but it may be made from insulator. One of the third support  140  ends is connected with a side which is farther from cylinder  110  on the second support  130 . The other end of the third support  140  reaches the outside wall of cylinder block  100 . And electromagnetic wave transmission line  830  is installed in the third support  140 . The electromagnetic wave transmission line  830  is made from copper wire. The electromagnetic wave transmission line  830  may be made from conductor, dielectric, or insulator and so on. However, electromagnetic waves must be transmitted well to the antenna  820  upon supplying electromagnetic waves between the earthed member and the electromagnetic wave transmission line. A variation example of the electromagnetic waves transmission line is an electromagnetic waves transmission line which consists of a waveguide made from conductor or dielectric. Here, the electromagnetic wave transmission line  830  is buried in the third support  140 , and pass through the third support  140 . One end of the electromagnetic wave transmission line  830  is connected with the antenna  820 . The other end of the electromagnetic wave transmission line  830  is extracted from the outside wall of cylinder block  100  to outside. Thus, when electromagnetic waves are supplied between electromagnetic wave transmission line  830  and cylinder block  100  that is the earth member, they are introduced into antenna  820 . 
     Electromagnetic wave generator  840 , which supplies electromagnetic waves to electromagnetic wave transmission line, is installed in internal combustion engine E or its surroundings. Electromagnetic wave generator  840  generates electromagnetic waves. In this embodiment of electromagnetic wave generator  840  is a magnetron that generates 2.45-GHz-bandwidth microwaves. However, this does not restrict interpretation of composition of electromagnetic wave generator of the after-treatment apparatus for gas of the present invention. 
     And discharge is generated with the electrode  811  of the discharge device  810  and the electromagnetic waves fed from the electromagnetic wave generator  840  through the electromagnetic wave transmission line  830  are radiated from the antenna  820 , while the exhaust gas remains in the combustion chamber  400  after the exhaust gas is produced during the explosion stroke in this after-treatment apparatus for gas. In addition, discharge is generated with the electrode  811  of the discharge device  810  and the electromagnetic waves fed from the electromagnetic wave generator  840  through the electromagnetic wave transmission line  830  are radiated from an antenna  820  from the time when exhaust gas is produced at the explosion stroke to the time when the intake valves  510  open the intake ports  310  or the exhaust valves  520  open the exhaust ports  320  in this after-treatment apparatus for gas (Refer to  FIG. 4 ). Cylinder block  100  is earthed. The earth terminals of discharge voltage generator  950  and electromagnetic wave generator  840  are earthed. Discharge voltage generator  950  and electromagnetic wave generator  840  are controlled by controller  880 , which has a CPU, memory, and storage etc, and outputs control signals after computing input signals. A signal line from crank angle detector  890  for detecting crank angle of crankshaft  920  is connected to control unit  880 . Crank angle detection signals are sent from crank angle detector  890  to controller  880 . Therefore, controller  880  receives signals from crank angle detector  890  and controls the actuations of discharge device  810  and electromagnetic wave generator  840 . However, this does not restrict the control method and the composition of the input-output signals as for the after-treatment apparatus for exhaust gas in a combustion chamber of the present invention. 
     As a modification, the setting of controller  880  is changed from said embodiment. In this after-treatment apparatus for exhaust gas in a combustion chamber, discharge is generated with the electrode  811  of the discharge device  810  and the electromagnetic waves fed from the electromagnetic wave generator  840  through the electromagnetic wave transmission line  830  are radiated from an antenna  820  from the time when exhaust gas is produced at the explosion stroke to not the time when the intake valves  510  open the intake ports  310  or the exhaust valves  520  open the exhaust ports  320  but the time after the exhaust valves  520  begin to open (Refer to  FIG. 5 ). 
     In the actuation of the internal combustion engine E, discharge is generated at the electrode  811  of the discharge device  810  and the electromagnetic waves fed from the electromagnetic wave generator  840  through the electromagnetic wave transmission line  830  are radiated from the antenna  820 . Therefore, the plasma is generated near the electrode  811 . This plasma receives energy of an electromagnetic waves (electromagnetic wave pulse) supplied from the antenna  820  for a given period of time. As a result, the plasma generates a large amount of OH radicals and ozone to promote the oxidation reaction etc. of the exhaust gas components. In fact electrons near the electrode are accelerated, fly out of the plasma area, and collide with gas such as air or the air-fuel mixture in surrounding area of said plasma. The gas in the surrounding area is ionized by these collisions and becomes plasma. Electrons also exist in the newly formed plasma. These also are accelerated by the electromagnetic wave pulse and collide with surrounding gas. The gas ionizes like an avalanche and floating electrons are produced in the surrounding area by chains of these electron acceleration and collision with electron and gas inside plasma. These phenomena spread to the area around discharge plasma in sequence, then the surrounding area get into plasma state. In the result of the phenomena as mentioned above it, the volume of plasma increases. Then the electrons recombine rather than dissociate at the time when the electromagnetic wave pulse radiation is stopped. As a result, the electron density decreases, and the volume of plasma decreases as well. The plasma disappears when the electron recombination is completed. A large amount of OH radicals and ozone is generated from moisture in the gas mixture as a result of a large amount of the generated plasma, promoting the oxidation reaction etc. of the exhaust gas components. 
     In that case, oxidation reaction etc. is initiated in the combustion chamber  400  as a reactor while exhaust gas remains in the combustion chamber  400  after the exhaust gas is produced during explosion stroke. The high temperature of the exhaust gas also promotes the oxidation reactions, which increases cleanup efficiency in combination with the oxidation reaction etc. obtained by generating a large amount of OH radicals and ozone with plasma. Therefore, it is not necessary to use a rich air-to-fuel ratio or afterburning downstream of the combustion chamber, which would prevent the mileage reduction of the internal combustion engine. 
     In addition, until the intake valves  510  open the intake ports  310  or the exhaust valves  520  open the exhaust ports  320  after generation exhaust gas by explosion stroke, The electromagnetic waves scattering from the combustion chamber  400  to outside is prevented. Moreover, the back face of the intake valves  510  or the exhaust valves  520  prevent some electromagnetic waves from scattering from the combustion chamber  400  to the intake port  310  or the exhaust port  320  after the intake valves  510  open the intake ports  310  or the exhaust valves  510  opens the exhaust ports  320 . Therefore, closed space of the combustion chamber  400  or space according to it becomes a reactor, where the oxidation reaction etc. of the exhaust gas components is stably initiated. 
     The after-treatment apparatus for exhaust gas in a combustion chamber of the present invention may be configured such that discharge is generated with the electrode of the discharge device and the electromagnetic waves fed from the electromagnetic wave generator through the electromagnetic wave transmission line are radiated from the antenna, while the exhaust gas remains in the combustion chamber after the exhaust gas is produced during the explosion stroke. Control method shown in  FIG. 5  and explained is one example. Even though there are various embodiments, the after-treatment apparatus for exhaust gas in a combustion chamber of the first embodiment is configured such that discharge is generated with the electrode  811  of the discharge device  810  and the electromagnetic waves fed from the electromagnetic wave generator  840  through the electromagnetic wave transmission line  830  are radiated from an antenna  820 , from the time when exhaust gas is produced at the explosion stroke to the time when the intake valves  510  open the intake ports  310  or the exhaust valves  520  open the exhaust ports  320 , as the explanation using  FIG. 4 . This makes it possible that the intake valves  510  and exhaust valves  520  prevent electromagnetic waves from scattering from the combustion chamber  400  to outside. Therefore, closed space of the combustion chamber  400  becomes a reactor, where the oxidation reaction etc. of the exhaust gas components is stably initiated. 
     The after-treatment apparatus for exhaust gas in a combustion chamber of the present invention may be configured such that discharge is generated with the electrode of the discharge device and the electromagnetic waves fed from the electromagnetic wave generator through the electromagnetic wave transmission line are radiated from the antenna, while the exhaust gas remains in the combustion chamber after the exhaust gas is produced during the explosion stroke. This does not restrict the control method and the composition of the input-output signals of discharge device or electromagnetic wave generator. Even though there are various embodiments, the after-treatment apparatus for exhaust gas in a combustion chamber of the first embodiment comprises crank angle detector  890  and controller  880 . Crank angle detector  890  detects the crank angle of crank shaft  920 . Controller  880  receives the signal from this crank angle detector  890 , and controls the operation of discharge device  810  and electromagnetic wave generator  840 . This makes it possible that discharge at the electrode  811  and the radiation of the electromagnetic waves from the antenna  820  are controlled according to the crank angle. 
     The positional relationship between the antenna and the electrodes is not restricted in the after-treatment apparatus for exhaust gas in a combustion chamber of the present invention. Even though there are various embodiments, the electrode  811  is located close to a portion that the electric field intensity generated by the electromagnetic waves strengthens in the antenna  820  when the electromagnetic waves are fed into the antenna  820  in the after-treatment apparatus for exhaust gas in a combustion chamber of the first embodiment. This makes it possible that the electrical field intensity, due to the electromagnetic waves radiated from said portion of the antenna  820 , is stronger than the electrical field intensity of the surrounding electromagnetic waves. Therefore, the energy of the electromagnetic wave pulse is intensively supplied to the plasma generated by discharge at the electrode  811 . As a result, a large amount of OH radicals and ozone is efficiently generated, further promoting the oxidation reaction etc. of the exhaust gas components in the area centered at the electrode  811 . When there are multiple areas of the antenna  820  with strong electrical field intensity, the oxidation reaction etc. of the exhaust gas components at multiple areas of the combustion chamber  400  is further promoted upon the portion approaching to the electrode  811 . 
     Next, other embodiments of the after-treatment apparatus for exhaust gas in a combustion chamber of the present invention will be described. In the after-treatment apparatus for exhaust gas in first embodiment, discharge devices  810 , antenna  820 , and electromagnetic wave transmission line  830  are installed in the cylinder block  100  of the members constituting the combustion chamber  400 . In the after-treatment apparatus for exhaust gas in second embodiment, discharge device  760 , antenna  770 , and electromagnetic wave transmission line  780  were installed in the gasket  700  of the members constituting the combustion chamber  400 . 
     Hereinafter, the after-treatment apparatus for exhaust gas in a combustion chamber in second embodiment will be described.  FIG. 6  shows the embodiment of the internal combustion engine E with the gasket  700 . The present invention targets reciprocating engines. In this embodiment, engine E is a four-cycle gasoline engine. Item  100  is the cylinder block. Cylinder block  100  contains cylinder  110 , which has an approximately circular cross section. Cylinder  110  penetrates cylinder block  100 . Piston  200 , which has an approximately circular cross section corresponding to cylinder  110 , fits into cylinder  110  and reciprocates freely. Cylinder head  300  is assembled on the anti-crankcase side of cylinder block  110 . Cylinder head  300 , piston  200 , and cylinder  110  form combustion chamber  400 . Item  910  is a connecting rod, with one end connected to piston  200  and the other end connected to crankshaft  920 , which is the output shaft. Cylinder head  300  has intake port  310 , which is a component of the intake line, and exhaust port  320 , which is a component of the exhaust line. One end of intake port  310  connects to combustion chamber  400 ; the other end is open at the outside wall of cylinder head  300 . One end of exhaust port  320  connects to combustion chamber  400 ; the other end is open at the outside wall of cylinder head  300 . The cylinder head has guide hole  330  that passes through intake port  310  to the outside wall of cylinder head  300 . Valve stem  511  of intake valve  510  fits into guide hole  330  and reciprocates freely. Valve head  512 , set at the end of valve stem  511 , opens and closes the combustion chamber side opening of intake port  310  at a given timing by a valve open/close mechanism having a cam and so on (not shown in the figure). Cylinder head  300  has guide hole  340  that passes through exhaust port  320  to the outside wall of cylinder head  300 . Valve stem  521  of exhaust valve  520  fits into guide hole  340  and reciprocates freely. Valve head  522 , set at the end of valve stem  521 , opens and closes the combustion chamber side opening  321  of the exhaust port  320  at a given time by the valve open/close mechanism having cam and so on (not shown in the figure). Item  600  is a spark plug installed in cylinder head  300  to expose the electrode to combustion chamber  400 . Spark plug  600  discharges at the electrodes when piston  200  is near top dead center. Therefore, four strokes (intake, compression, combustion of mixture, and exhaust of exhaust gas) occur while piston  200  reciprocates between top dead center and bottom dead center twice. However, this embodiment does not restrict the interpretation of the internal combustion engine targeted by the present invention. The present invention is also suitable for use with two-stroke internal combustion engines and diesel engines. Target gasoline engines include direct-injection gasoline engines, which create a mixture inside the combustion chamber to inject fuel into the intake air. Target diesel engines include direct-injection diesel engines, which inject fuel into the combustion chamber directly, and divided-chamber diesel engines, which inject fuel into divided chamber. Internal combustion engine E in this embodiment has four cylinders, but this does not restrict number of cylinders of the internal combustion engine targeted by the present invention. The internal combustion engine for this embodiment has two intake valves  510  and two exhaust valves  520 , but this does not restrict the number of intake or exhaust valves of the internal combustion engine targeted by the present invention. 
     Gasket  700  shown in  FIG. 7  is installed between cylinder block  100  and cylinder head  300 . Gasket  700  is shaped like a thin board with an almost constant thickness. Gasket  700  has an opening corresponding to cylinder  110 . Additionally, gasket  700  has holes corresponding to the water jacket and bolt holes. These do not restrict interpretation of the gasket shape targeted by the present invention. 
     As shown in  FIGS. 8 and 9 , discharge line  760  is installed in intermediate layer  730  of gasket  700  in thickness direction as a discharge device. The intermediate layer  730  in thickness direction is a layer formed in the middle part of the direction of thickness. The intermediate layer  730  is made from ceramics. Intermediate layer can also be made from synthetic rubbers, fluoroplastics, silicone resin, synthetic resin, such as a meta system of aramid fiber seats, and heatproof paper. Thus, the intermediate layer may be made from a dielectric, but made from an insulator. Discharge line  760  is made from copper line, but may be made from another conductive material. Discharge line  760  is buried between outer peripheral edge  720  and opening  710  of gasket  700 . The outside edge of discharge line  760  is exposed from outer peripheral edge  720  of gasket  700  to become first connector  761 . Moreover, the inside edge of the discharge line  760  is exposed from the outer edge of the gasket  700  towards the center of opening  710  to become electrode  762 . Surface layers  740 , which exist on both sides of intermediate layer  730  in thickness direction, are made from a conductive material. One surface layer  740  comes in contact with one surface of cylinder block  100  when gasket  700  is installed between cylinder block  100  and cylinder head  300 . The other surface layer  740  comes in contact with one surface of cylinder head  300 . Surface layers  740  are made from metal, although they could also be made from other materials. Although both surface layers  740  in thickness direction are made from a conductive material in this embodiment, the present invention includes the case in which only one surface layer to the intermediate layer  730  in thickness direction is made from a conductive material. Therefore, when the cylinder block  100 , cylinder head  300  or surface layer  740  is earthed, and voltage is applied between first connector  761  and an earth member, which can be the cylinder block  100 , cylinder head  300  or surface layers  740 , a discharge is generated between first connector  761  and the earth member. In this embodiment, part of discharge line  760  except the electrode and the electrode are formed from the same material as one body. However, part of discharge line except the electrode and the electrode are formed separately and connected. Part of discharge line  760  except the electrode and the electrode are made from the different material. 
     As shown in  FIGS. 8 and 10 , antenna  770  is installed in gasket  700 . Antenna  770  is made from metal, although it could also be made from any conductive material, insulator, or dielectric provided that electromagnetic waves radiate well from the antenna to the combustion chamber when they are applied between the antenna and the earthed members. Antenna  770  is installed in gasket intermediate layer  730  in thickness direction at the inner peripheral edge around opening  710  to radiate electromagnetic waves to the combustion chamber  400 . Antenna  770  is rod-shaped. Its base end is installed in intermediate layer  730  in thickness direction. A part to leading end except said base end in this antenna  770  is curved in a nearly circular arc. Antenna  770  extends along the inner peripheral edge around the opening  710  in the circumferential direction of the opening  710 . For example, the length of the circular arc part of antenna  770  is set to a quarter of the wavelength of the electromagnetic waves so that standing waves are generated in the antenna  770 , increasing the electrical field strength at the end of the antenna  770 . For example, the length of the circular arc part of antenna  770  is set to a multiple of a quarter wavelengths of the electromagnetic waves so that standing waves are generated in the antenna  770 , increasing the electrical field at multiple points, where the anti-nodes of the standing waves are generated, in the antenna  770 . Here, the entire length of antenna  770  is almost buried in intermediate layer  730 . As shown in  FIG. 10 , the solid cross-section of antenna  770  is approximately circular for its entire length. The antenna  770  contacts a surface which is an inner edge of opening  710  of intermediate layer  730  from the inside at one concyclic point in the section along its entire length. This part of antenna  770  is exposed from the inner edge of opening  710  to combustion chamber  400  on the section. However, antenna  770  of the present invention is not restricted to a circular cross-sectional shape. Antenna  770  may be buried in intermediate layer  730  completely. Additionally, said electrode  762  is located close to a portion of strong electrical field intensity in the antenna  770  due to the electromagnetic waves when the electromagnetic waves are fed to the antenna  770 . Here, the leading end of antenna  770  and electrode  762  are close to each other along the inner peripheral edge of opening  710 , with a prescribed gap between them. As a result, a stripline track is formed. Thus, when electromagnetic waves are supplied between first connector  761  and said earth member, the electromagnetic waves are radiated from antenna  770  to combustion chamber  400 . The earth member may double as the earth side of the stripline track concurrently. For this embodiment, antenna  770  is a rod-shaped monopole antenna that is curved one. However, this does not restrict the type of antenna in the gasket of the present invention. Therefore, antenna of the gasket of the present invention may be dipole type, Yagi-Uda type, single wire type, loop type, phase difference feeder type, grounded type, ungrounded and perpendicular type, beam type, horizontal polarized omni-directional type, corner-reflector type, comb type or other type of linear antenna, microstrip type, planar inverted F type or other type of flat antenna, slot type, parabola type, horn type, horn reflector type, Cassegrain type or other type of solid antenna, Beverage type or other type of traveling-wave antenna, star EH type, bridge EH type or other type of EH antennas, bar type, small loop type or other type of magnetic antenna, or dielectric antenna. 
     As shown in  FIGS. 8 and 10 , antenna  770  is installed in gasket  700 . Antenna  770  is made from metal, although it could also be made from any conductive material, insulator, or dielectric provided that electromagnetic waves radiate well from the antenna to the combustion chamber when they are applied between the antenna and the earthed members. Antenna  770  is installed in gasket intermediate layer  730  in thickness direction at the inner peripheral edge around opening  710  to radiate electromagnetic waves to the combustion chamber  400 . Antenna  770  is rod-shaped. Its base end is installed in intermediate layer  730  in thickness direction. A part to leading end except said base end in this antenna  770  is curved in a nearly circular arc. Antenna  770  extends along the inner peripheral edge around the opening  710  in the circumferential direction of the opening  710 . For example, the length of the circular arc part of antenna  770  is set to a quarter of the wavelength of the electromagnetic waves so that standing waves are generated in the antenna  770 , increasing the electrical field strength at the end of the antenna  770 . For example, the length of the circular arc part of antenna  770  is set to a multiple of a quarter wavelengths of the electromagnetic waves so that standing waves are generated in the antenna  770 , increasing the electrical field at multiple points, where the anti-nodes of the standing waves are generated, in the antenna  770 . Here, the entire length of antenna  770  is almost buried in intermediate layer  730 . As shown in  FIG. 10 , the solid cross-section of antenna  770  is approximately circular for its entire length. The antenna  770  contacts a surface which is an inner edge of opening  710  of intermediate layer  730  from the inside at one concyclic point in the section along its entire length. This part of antenna  770  is exposed from the inner edge of opening  710  to combustion chamber  400  on the section. However, antenna  770  of the present invention is not restricted to a circular cross-sectional shape. Antenna  770  may be buried in intermediate layer  730  completely. Additionally, said electrode  762  is located close to a portion of strong electrical field intensity in the antenna  770  due to the electromagnetic waves when the electromagnetic waves are fed to the antenna  770 . Here, the leading end of antenna  770  and electrode  762  are close to each other along the inner peripheral edge of opening  710 , with a prescribed gap between them. As a result, a stripline track is formed. Thus, when electromagnetic waves are supplied between first connector  761  and said earth member, the electromagnetic waves are radiated from antenna  770  to combustion chamber  400 . The earth member may double as the earth side of the stripline track concurrently. For this embodiment, antenna  770  is a rod-shaped monopole antenna that is curved one. However, this does not restrict the type of antenna in the gasket of the present invention. Therefore, antenna of the gasket of the present invention may be dipole type, Yagi-Uda type, single wire type, loop type, phase difference feeder type, grounded type, ungrounded and perpendicular type, beam type, horizontal polarized omni-directional type, corner-reflector type, comb type or other type of linear antenna, microstrip type, planar inverted F type or other type of flat antenna, slot type, parabola type, horn type, horn reflector type, Cassegrain type or other type of solid antenna, Beverage type or other type of traveling-wave antenna, star EH type, bridge EH type or other type of EH antennas, bar type, small loop type or other type of magnetic antenna, or dielectric antenna. 
     As shown in  FIGS. 8 and 10 , electromagnetic wave transmission line  780  is installed in intermediate layer  730  of gasket  700  in thickness direction. Electromagnetic wave transmission line  780  is made from copper line, although it could also be made from any conductive material, insulator, or dielectric provided that electromagnetic waves are transmitted well to the antenna  770  when they are supplied between the antenna and the earthed member. An example of a variation of the electromagnetic wave transmission line is one that consists of a waveguide made from a conductive material or dielectric. Electromagnetic wave transmission line  780  is buried between outer peripheral edge  720  and opening  710  in gasket  700 . The outside edge of electromagnetic wave transmission line  780  is exposed from outer peripheral edge  720  of gasket  700  to become second connector  781 . The inside edge of electromagnetic wave transmission line  780  connects with antenna  770  in intermediate layer  730 . Thus, the electromagnetic waves are led to antenna  770  when electromagnetic waves are supplied between second connector  781  and the earthed member. 
     Gasket  700  electrically insulates discharge line  760 , antenna  770 , electromagnetic wave transmission line  780 , and both surfaces of the gasket in thickness direction. Cylinder block  100 , cylinder head  300 , or surface layer  740  is earthed. The anode of discharge voltage generator  950  is connected to first connector  761 . The anode of electromagnetic wave generator  840  is connected to second connector  781 . The earth terminals of discharge voltage generator  950  and electromagnetic wave generator  840  are earthed. Discharge voltage generator  950  and electromagnetic wave generator  840  are controlled by controller  880 , which has a CPU, memory, and storage etc, and outputs control signals after computing input signals. A signal line from crank angle detector  890  for detecting crank angle of crankshaft  920  is connected to control unit  880 . Crank angle detection signals are sent from crank angle detector  890  to controller  880 . Therefore, controller  880  receives signals from crank angle detector  890  and controls the actuations of discharge device  760  and electromagnetic wave generator  840 . Discharge voltage generator  950  in this embodiment is a 12-V DC power source, but this can also be a piezo element or other device. Electromagnetic wave generator  840  generates electromagnetic waves. Electromagnetic wave generator  840  in this embodiment is a magnetron that generates 2.4-GHz-bandwidth microwaves. However, this does not restrict the control method and the composition of the input-output signals as for gasket of the present invention. 
     Therefore, the gasket is installed between the cylinder block  100  and cylinder head  300  so that its opening  710  corresponds to the cylinder  110 . A piston  200  fits into the cylinder  110  and reciprocates freely. The internal combustion engine E operating normally as a gasoline engine is assembled up. It makes possible to apply voltage between first connector  761  of the discharge line  760  and the earth member. It makes possible to feed electromagnetic waves between the second connector  781  and the earth member for a constant time. And voltage is applied to the first connector  761  of the discharge line  760  and the earthed member and the electromagnetic waves are fed to the second connector  781  of the electromagnetic wave transmission line and the earthed member while the exhaust gas remains in the combustion chamber after the exhaust gas is produced in the actuation of the internal combustion engine E. Therefore, the plasma is generated near the electrode  762 . This plasma receives energy of an electromagnetic waves (electromagnetic wave pulse) supplied from the antenna  770  for a given period of time. As a result, the plasma generates a large amount of OH radicals and ozone to promote the oxidation reaction etc. of the exhaust gas components. In fact electrons near the electrode  762  are accelerated, fly out of the plasma area, and collide with gas such as air or the air-fuel mixture in surrounding area of said plasma. The gas in the surrounding area is ionized by these collisions and becomes plasma. Electrons also exist in the newly formed plasma. These also are accelerated by the electromagnetic wave pulse and collide with surrounding gas. The gas ionizes like an avalanche and floating electrons are produced in the surrounding area by chains of these electron acceleration and collision with electron and gas inside plasma. These phenomena spread to the area around discharge plasma in sequence, then the surrounding area get into plasma state. In the result of the phenomena as mentioned above it, the volume of plasma increases. Then the electrons recombine rather than dissociate at the time when the electromagnetic wave pulse radiation is stopped. As a result, the electron density decreases, and the volume of plasma decreases as well. The plasma disappears when the electron recombination is completed. A large amount of OH radicals and ozone is generated from moisture in the gas mixture as a result of a large amount of the generated plasma, promoting the oxidation reaction etc. of the exhaust gas components. 
     In that case, oxidation reaction etc. is initiated in the combustion chamber  400  as a reactor while exhaust gas remains in the combustion chamber after the exhaust gas is produced at explosion stroke. The high temperature of the exhaust gas also promotes the oxidation reactions, which increases cleanup efficiency in combination with the oxidation reaction etc. obtained by generating a large amount of OH radicals and ozone with plasma. Therefore, it is not necessary to use a rich air-to-fuel ratio or afterburning downstream of the combustion chamber, which would prevent the mileage reduction of the internal combustion engine. 
     In addition, until the intake valves  510  open the intake ports  310  or the exhaust valves  520  open the exhaust ports  320  after generation exhaust gas by explosion stroke, the electromagnetic waves scattering from the combustion chamber  400  to outside is prevented. Moreover, the back face of the intake valves  510  or the exhaust valves  520  prevent some electromagnetic waves from scattering from the combustion chamber  400  to the intake port  310  or the exhaust port  320  after the intake valves  510  open the intake ports  310  or the exhaust valves  510  open the exhaust ports  320 . Therefore, closed space of the combustion chamber  400  or space according to it becomes a reactor, where the oxidation reaction etc. of the exhaust gas components is stably initiated. 
     The after-treatment apparatus for exhaust gas in a combustion chamber of the present invention may be configured such that discharge is generated with the electrode of the discharge device and the electromagnetic waves fed from the electromagnetic wave generator through the electromagnetic wave transmission line are radiated from the antenna, while the exhaust gas remains in the combustion chamber after the exhaust gas is produced during the explosion stroke. Control method shown in  FIG. 5  and explained is one example. Even though there are various embodiments, the after-treatment apparatus for exhaust gas in a combustion chamber of the second embodiment is configured such that discharge is generated with the electrode  762  of the discharge device  760  and the electromagnetic waves fed from the electromagnetic wave generator  840  through the electromagnetic wave transmission line  780  are radiated from an antenna  770 , from the time when exhaust gas is produced at the explosion stroke to the time when the intake valves  510  open the intake ports  310  or the exhaust valves  520  open the exhaust ports  320 , as the explanation using  FIG. 4 . This makes it possible that the intake valves  510  and exhaust valves  520  prevent electromagnetic waves from scattering from the combustion chamber  400  to outside. Therefore, closed space of the combustion chamber  400  becomes a reactor, where the oxidation reaction etc. of the exhaust gas components is stably initiated. 
     The after-treatment apparatus for exhaust gas in a combustion chamber of the present invention may be configured such that discharge is generated with the electrode of the discharge device and the electromagnetic waves fed from the electromagnetic wave generator through the electromagnetic wave transmission line are radiated from the antenna, while the exhaust gas remains in the combustion chamber after the exhaust gas is produced during the explosion stroke. This does not restrict the control method and the composition of the input-output signals of discharge device or electromagnetic wave generator. Even though there are various embodiments, the after-treatment apparatus for exhaust gas in a combustion chamber of the second embodiment comprises crank angle detector  890  and controller  880 . Crank angle detector  890  detects the crank angle of crank shaft  920 . Controller  880  receives the signal from this crank angle detector  890 , and controls the operation of discharge device  760  and electromagnetic wave generator  840 . This makes it possible that discharge at the electrode  762  and the radiation of the electromagnetic waves from the antenna  770  are controlled according to the crank angle. 
     The positional relationship between the antenna and the electrodes is not restricted in the after-treatment apparatus for exhaust gas in a combustion chamber of the present invention. Even though there are various embodiments, the electrode  762  is located close to a portion that the electric field intensity generated by the electromagnetic waves strengthens in the antenna  770  when the electromagnetic waves are fed into the antenna  770  in the after-treatment apparatus for exhaust gas in a combustion chamber of the second embodiment. This makes it possible that the electrical field intensity, due to the electromagnetic waves radiated from said portion of the antenna  770 , is stronger than the electrical field intensity of the surrounding electromagnetic waves. Therefore, the energy of the electromagnetic wave pulse is intensively supplied to the plasma generated by discharge at the electrode  762 . As a result, a large amount of OH radicals and ozone is efficiently generated, further promoting the oxidation reaction etc. of the exhaust gas components in the area centered at the electrode  762 . When there are multiple areas of the antenna  770  with strong electrical field intensity, the oxidation reaction etc. of the exhaust gas components at multiple areas of the combustion chamber  400  is further promoted upon the portion approaching to the electrode  762 . 
     In this case, the cylinder block  100  and cylinder head  300  etc. which are the major structural materials can be used without modification compared with existing internal combustion engine. All that is required are the applying of voltage to the discharge line  760  and the supply of the electromagnetic waves. Thus, it is realized to minimize the time required to design an engine E and facilitate the sharing of many parts between existing internal combustion engines. 
     The material of surface layers  740  on both sides of intermediate layer  730  in thickness direction is not restricted in the gasket of the internal combustion engine of the present invention. The surface layers may also be a dielectric or insulator. In the gasket of the embodiment, intermediate layer  730  is made from a dielectric, and surface layers  740  on both sides of intermediate layer  730  in thickness direction are made from a conductive material. Thus, surface layer  740  works as an earth electrode that pairs with electrode  762  of discharge line  760 . The discharge is generated between electrode  762  and surface layer  740 . Surface layer  740  also works as an earth conductive material that pairs with electromagnetic wave transmission line  780 . The electromagnetic waves are transmitted between electromagnetic wave transmission line  780  and surface layer  740 . If the intermediate layer is made from an insulator and the surface layers on both sides of the intermediate layer are made from a conductive material, the same function and effect are also gained. Moreover, if the intermediate layer is made from a dielectric or insulator and the surface layer on at least one side of the intermediate layer is made from a conductive material, the same function and effect are also gained. Additionally, the rigidity of gasket  700  improves because surface layer  740  is made from metal. 
     The structure and the shape of the antenna are not restricted in the gasket of the internal combustion engine of the present invention. The antenna  770  is rod-shaped as for the gasket  700  in the embodiment among such varied embodiments. The base end of the antenna  770  is installed in the intermediate layer  730  in thickness direction. A portion, to the leading end except the base end, extends along the inner peripheral edge around the opening  710  in the circumferential direction of the opening  710  in the antenna  770 . This makes it possible that the electrical field intensity near the outer edge of the combustion chamber  400 , generated by the electromagnetic waves radiated from the antenna  770 , is stronger than the electrical field intensity in other areas of the combustion chamber  400 . Therefore, the amount of OH radicals and ozone in the vicinity of the outer edge of the combustion chamber  400  is more than the amount of other areas. Oxidation reaction etc. in this area is promoted more than in other areas. Mixing of OH radicals or ozone and the air-fuel mixture is promoted by Squish Flow, Tumble or Swirl in the vicinity of the outside edge of the combustion chamber  400 . 
     The positional relationship between the antenna and the electrode is not restricted in the gasket of the internal combustion engine of the present invention. Electrode  762  is located close to a portion of strong electrical field intensity in the antenna  770  due to the electromagnetic waves when the electromagnetic waves are fed to the antenna  770  in the embodiment among such varied embodiments. This makes it possible that the electrical field intensity, due to the electromagnetic waves radiated from said portion of the antenna  770 , is stronger than the electrical field intensity of the surrounding electromagnetic waves. Therefore, the energy of the electromagnetic wave pulse is intensively supplied to the plasma generated by discharge at the electrode  762 . As a result, a large amount of OH radicals and ozone is efficiently generated, further promoting oxidation reaction etc. in the area centered at the electrode  762 . When there are multiple areas of the antenna  770  with strong electrical field intensity, oxidation reaction etc. at multiple areas of the combustion chamber  400  is further promoted upon the portion approaching to the electrode  762 . 
     Other modifications of the gasket of the present invention will be described in the following paragraphs. In the description of the gasket of these other modifications, members and portions, which fulfill the same function as the gasket  700  in the second embodiment, will be applied to the same reference characters used in the second embodiment. The description of these members and portions will be omitted. And, difference points of the composition from the gasket  700  in the second embodiment will be explained about the gaskets of these other modifications. Therefore, the composition without the description is the same as the composition of the gasket  700  in the second embodiment. 
       FIG. 11  shows the first modification of gasket  700 . In the second embodiment of gasket  700 , the entire length of antenna  770  is almost buried in intermediate layer  730 . In the first modification, the base end of antenna  770  is located in intermediate layer  730  in thickness direction; the remainder of antenna  770  extends out from intermediate layer  730  towards the center of opening  710 , and then has an L-shaped curve. The end of antenna  770  is curved in an almost circular arc, and extends along the inner peripheral edge around opening  710 . Because antenna  770  of the second embodiment of gasket  700  is almost buried in intermediate layer  730  for its entire length, the heat load received from combustion chamber  400  and the fatigue of antenna  770  due to machine vibration is reduced. However, because antenna  770  is exposed to combustion chamber  400  in the first modification, the electrical field intensity due to the electromagnetic waves radiated from antenna  770  becomes stronger. Other functions and effects are similar to those described for the second embodiment of gasket  700 . 
       FIG. 12  shows the second modification of gasket  700 . Here, antenna  770  of this gasket  700  is longer than one in the first modification, although both gaskets are similar. The remainder of antenna  770  extends from the base end towards the center of opening  710 , and then has an L-shaped curve. The end of antenna  770  is curved in an almost circular arc, and extends along the inner peripheral edge around opening  710  for one entire loop. This makes it possible to earn the length of antenna  770  and strengthen up the electrical field intensity due to the electromagnetic waves radiated from the antenna. Other functions and effects are similar to those described for the first embodiment of gasket  700 . When antenna  770  becomes long like this, the standing waves are generated in the antenna  770 . Therefore, two or more portions, of which the electrical field intensity due to the electromagnetic waves becomes strong in the antenna  770 , can be in existence. The portions like this are more than the gasket having shorter antenna if wavelength of electromagnetic waves are same. In the third modification of gasket  700 , there are two or more electrodes  762  along the inner peripheral edge, spaced equally in gasket  700 , as shown in  FIG. 13 , though in the first modification of gasket  700  there is one electrode  762 . Each Electrode  762  is located close to area with strong electrical field intensities due to the electromagnetic waves radiated by the antenna  770 . This makes it possible that the electrical field intensity, due to the electromagnetic waves radiated from said portion of the antenna  770 , is stronger than the electrical field intensity of the surrounding electromagnetic waves. Therefore, the energy of the electromagnetic wave pulse from said portion is intensively supplied to the plasma generated by discharge at each electrode  762 . As a result, a large amount of OH radicals and ozone is efficiently generated, further promoting oxidation reaction in the area centered at the electrode  762 . Oxidation reaction at multiple areas of the combustion chamber  400  is further promoted. 
       FIG. 14  shows the fourth modification of gasket  700 . In the second embodiment of gasket  700 , not only discharge line  760  but electromagnetic wave transmission line  780  is made from copper wire. In the fourth modification, shielded cable S is installed in intermediate layer  730  and the cable core of the inner electrical cable of shielded cable S works as a an electromagnetic wave transmission line  780 . Shielded cable S comprises an inner wire, an external conductive material, and an external covering. The inner wire includes a core wire made from a conductive material such as copper, and an inner covering for the core wire made from an insulator. The external conductive material is made from a conductive material that covers the inner wire. The external covering is made from an insulator that covers the external conductive material. This makes the production of the gasket comparatively easy by using the shielded cable S. Other functions and effects are similar to those described for the second embodiment of gasket  700 . Shielded cable S may be installed in intermediate layer  730 , and discharge line  760  may be composed of the cable core with an inner wire of shielded cable S. 
       FIG. 15  shows the fifth modification of gasket  700 . In the second embodiment of gasket  700 , discharge line  760  is installed in intermediate layer  730  in thickness direction. The anode of voltage generator  950  is connected with first connector  761  of discharge line  760 . Cylinder block  100 , cylinder head  300 , or surface layer  740  is earthed to become an earth member. When voltage is applied between first connector  761  and said earth member, a discharge is generated between first connector  761  and the earth member. In the fifth modification, a pair of discharge lines  760  is installed in intermediate layer  730  of gasket  700 . The outside edge of each discharge line  760  is exposed from outer peripheral edge  720  of gasket  700  to become first connector  761 . Moreover, the inside edge of the each discharge line  760  is exposed from the outer edge of the gasket  700  towards the center of opening  710  to become electrode  762 . These electrodes  762  of discharge lines  760  are arranged adjacent to each other. This makes it possible that a discharge is generated between the electrodes when voltage is applied between first connection parts of the discharge line  760 . When the electrodes  762  of these discharge lines  760  are arranged adjacent to each other, a discharge can be generated using a low voltage. And the generation of OH radicals and ozone is promoted. The duration of this generated OH radicals and ozone becomes long. Power consumption is reduced. Moreover, the amount of nitrogen oxide (NOx) in the internal combustion engine is reduced because of the reduced of temperature rise in the area where discharge is generated. Other functions and effects are similar to those described for the second embodiment of gasket  700 . 
     Next, the after-treatment apparatus for exhaust gas in third embodiment will be described. In the after-treatment apparatus for exhaust gas in third embodiment, discharge devices  810  is installed in the cylinder head  300  of the members constituting the combustion chamber  400 , antenna  820  is installed on the exhaust valve  520 , and electromagnetic wave transmission line  830  is installed in the cylinder head  300 . 
     Hereinafter, the after-treatment apparatus for exhaust gas in a combustion chamber in third embodiment will be described.  FIG. 16  shows the embodiment of the internal combustion engine E. The present invention targets reciprocating engines. In this embodiment, engine E is a four-cycle gasoline engine. Cylinder block  100  contains cylinder  110 , which has an approximately circular cross section. Cylinder  110  penetrates cylinder block  100 . Piston  200 , which has an approximately circular cross section corresponding to cylinder  110 , fits into cylinder  110  and reciprocates freely. Cylinder head  300  is assembled on the anti-crankcase side of cylinder block  110 . Cylinder head  300 , piston  200 , and cylinder  110  form combustion chamber  400 . Item  910  is a connecting rod, with one end connected to piston  200  and the other end connected to crankshaft  920 , which is the output shaft. Cylinder head  300  has intake port  310 , which is a component of the intake line, and exhaust port  320 , which is a component of the exhaust line. One end of intake port  310  connects to combustion chamber  400 ; the other end is open at the outside wall of cylinder head  300 . One end of exhaust port  320  connects to combustion chamber  400 ; the other end is open at the outside wall of cylinder head  300 . The cylinder head has guide hole  330  that passes through intake port  310  to the outside wall of cylinder head  300 . Rod-shaped valve stem  511  of intake valve  510  fits into guiding hole  330  and reciprocates freely. Umbrella-shaped valve head  512 , set at the end of valve stem  511 , opens and closes the combustion chamber side opening  311  of intake port  310  at a given timing by a valve open/close mechanism having a cam and so on (not shown in the figure). Cylinder head  300  has guiding hole  340  that passes through exhaust port  320  to the outside wall of cylinder head  300 . Rod-shaped valve stem  521  of exhaust valve  520  fits into guiding hole  340  and reciprocates freely. Umbrella-shaped valve head  522 , set at the end of valve stem  521 , opens and closes the combustion chamber side opening  321  of the exhaust port  320  at a given time by the valve open/close mechanism having cam and so on (not shown in the figure). Item  810  is a spark plug installed in cylinder head  300  to expose a pair of electrodes  812 ,  813  to combustion chamber  400 . Spark plug  810  discharges at the electrodes when piston  200  is near top dead center. Therefore, four strokes (intake, compression, combustion of mixture, and exhaust of exhaust gas) occur while piston  200  reciprocates between top dead center and bottom dead center twice. However, this embodiment does not restrict the interpretation of the internal combustion engine targeted by the present invention. The present invention is also suitable for use with two-stroke internal combustion engines and diesel engines. Target gasoline engines include direct-injection gasoline engines, which create a mixture inside the combustion chamber to inject fuel into the intake air. Target diesel engines include direct-injection diesel engines, which inject fuel into the combustion chamber directly, and divided-chamber diesel engines, which inject fuel into the divided chamber. Internal combustion engine E in this embodiment has four cylinders, but this does not restrict number of cylinders of the internal combustion engine targeted by the present invention. The internal combustion engine for this embodiment has two intake valves  510  and two exhaust valves  520 , but this does not restrict the number of intake or exhaust valves of the internal combustion engine targeted by the present invention. Item  700  is a gasket installed between cylinder block  100  and cylinder head  300 . 
     Said spark plug  810  also functions as a discharge device  810  of the after-treatment apparatus for exhaust gas of the present invention. This discharge device  810  is installed in the cylinder head  300 . This discharge device  810  is set on the wall of the combustion chamber  400 . This discharge device  810  comprises a connection  811  set outside of the combustion chamber  400 , a first electrode  812  electrically-connected to the connection  811 , and a second electrode  813  contacts the cylinder head  300  and connects in ground. The first electrode  812  and the second electrode  813  are placed opposite at specified interval on the discharge device  810 . Both of them are exposed to the combustion chamber  400 . The discharge device  810  is connected to a discharge voltage generator  950  which generates voltage for discharge. Here, the discharge voltage generator  950  is DC 12V power supply and a spark coil. The cylinder head  300  is earthed and the connection  811  connects to the discharge voltage generator  950 . In case of applying voltage between the cylinder head  300  and the connection  811 , discharge happens between the first electrode  812  and the second electrode  813 . As described above, it may discharge between electrode of the discharge device and a wall of the combustion chamber, or other earthed members without a pair of electrodes. For example, in case that the internal combustion engine is a diesel engine, it does not install a spark plug under normal circumstances. Therefore it needs to install the discharge device, having an electrode exposed to the combustion chamber, on the cylinder head. In this case, it may install the spark plug as explained above as the discharge device, and connects it to the discharge voltage generator. However the discharge device does not always need to use a spark plug, because the discharge device requires generating plasma by discharge regardless the size. The discharge device may be used for example piezo element or other device. 
     An antenna  820  is installed on the valve face  522   b  of the valve head  522  of said exhaust valve  520  as shown in  FIG. 17  and  FIG. 19 . The valve face  522   b  is a surface on opposite side against a back-face faces to the exhaust port  320  of the valve head  522 . The valve face  522   b  faces the combustion chamber  400  when the combustion chamber opening  321  of the exhaust port  320  is closed with the valve head  522 . The antenna  820  is made from metal. However, it can be made from a conductor, dielectric or insulator, provided that electromagnetic waves are radiated well from it to the combustion chamber when they are supplied between the antenna and the earth member. The Antenna  820  is a bar-style unit with curvature and forms nearly a C shape to surround the center of the valve face  522   b  of the valve head  522 . The antenna  820  radiates electromagnetic waves to the combustion chamber  400 . In fact, the antenna  820  forms nearly a C shape, in sum circularity with hiatus, to surround valve face  522   b , as seen along the direction of valve stem  521  extending. The inside of a portion of the valve stem  521  fitting into a guide hole  340  is made from dielectric and becomes a basic portion  521   a . A periphery side portion of this basic portion  521   a , the portion fits into the guide hole  340 , is made from metal and becomes a periphery portion  521   b . A reason for the periphery portion  521   b  made from metal is to enhance rub resistance and burning resistance, and it can be made from other materials. Also, no fitting portions into the guide hole  340  can be made from dielectric on the valve stem  521 . In addition, a successive portion to the basic portion  521   a  of said valve stem  521  is made from dielectric and becomes a basic portion  522   a  in the valve head  522 . And a valve face  522   b  on the combustion chamber side of the valve head  522  is made from metal. A reason for the valve face  522   b  made from metal is to enhance burning resistance. However, it can be made from other materials. The antenna  820  is installed on the back of the basic portion  522   a  in the valve head  522 . In this case, ceramic is used as dielectric. However, other dielectrics or insults can be used. For example, the length of the antenna  820  is set to a quarter of wavelength in electromagnetic waves, standing wave is generated in the antenna  820 . Thus, electrical field strength at the end of antenna  820  becomes strong. For example, the length of the antenna  820  is set to a multiple of a quarter wavelengths of the electromagnetic waves so that standing waves are generated in the antenna  820 , increasing the electrical field at multiple points, where the anti-nodes of the standing waves are generated, in the antenna  820 . The antenna  820  can be buried in the valve head  522 . In addition, the first electrode  821  and the second electrode  813  are located close to a portion that electric field intensity, generated by the electromagnetic waves around the valve face  522   b  of the valve head  522 , becomes strong when the electromagnetic waves are fed to said antenna  820 . In this case, the top of the antenna  820  gets close to the first current  812  and the second current  813 . Therefore, upon supplying electromagnetic waves between the antenna  820  and the cylinder head  300 , which is an earth member, the electromagnetic waves is radiated from the antenna  820  to the combustion chamber  400 . And, one end of the antenna  820  connects to the electromagnetic wave transmission line  830 , which is explained in below. In this embodiment, antenna  820  is a rod-shaped monopole antenna that is curved one. However, this does not restrict the type of antenna in the after-treatment apparatus for exhaust gas of the present invention. Therefore, antenna of the after-treatment apparatus for exhaust gas of the present invention may be dipole antenna, Yagi-Uda antenna, a single feed antenna, a loop antenna, a phase difference feed antenna. a ground-plane antenna, a anti-ground-plane type vertical antenna, a beam antenna, a horizontally polarized omni-directional antenna, a corner antenna, comb antenna, or one of the other linear antenna, a micro-strip antenna, a inverted-F antenna, or other plane antenna, slotted array antenna, a parabolic antenna, a horn antenna, a horn reflector antenna, a cassegrain antenna or other solid antennas, Beverage antenna or other progressive wave antennas, star type EH antennas, bridge type EH antennas or other EH antennas, a bar antenna, a minute loop antennas or one of the other magnetic field antennas or dielectric substance antennas. 
     Electromagnetic wave transmission line  830 , made from copper line, is installed in valve stem  521  of exhaust valve  520 , as shown in  FIG. 18 . This electromagnetic waves transmission line  780  is made from copper line. Electromagnetic wave transmission line  830  may also be made from any conductor, insulator, or dielectric, as long as electromagnetic waves are transmitted well to antenna  820  when they are supplied between antenna  820  and the earthed member. A possible variation is an electromagnetic wave transmission line that consists of a waveguide made from a conductor or dielectric. Power-receiving portion  521   c  is installed in a fitting portion into valve guide  340  of valve stem  521 . Power-receiving portion  521   c  can be made from a conductor, dielectric, or insulator. Here, power-receiving portion  521   c  is located at the periphery of valve stem  521 , but it can also be located inside it. The configuration and material of power-receiving portion  521   c  is selected according to the connection method to power-feeding member  860 , as described below. Power-receiving portion  521   c  can be positioned at a location farther from the valve head in the valve head than a fitting portion into the guide hole of the valve stem. One end of electromagnetic wave transmission line  830  is connected to antenna  820 . The other end, which is covered with an insulator or dielectric, extends to power-receiving portion  521   c  at a fitting portion into the guide hole  340  of valve stem  521  and connects to it. Electromagnetic wave transmission line  830  runs inside basic portion  521   a  of valve stem  521 . Therefore the other end of electromagnetic wave transmission line  830  is covered with a dielectric and extends to power-receiving portion  521   c . Whereas basic portion  521   a  is made from dielectric, the other end of the electromagnetic wave transmission line is covered with an insulator and extends to power-receiving portion. Thus, when electromagnetic waves are supplied between power-receiving portion  521   c  and the earth member such as cylinder head  300 , they are introduced into antenna  820 . 
     Electromagnetic wave generator  840 , which supplies electromagnetic waves to power-receiving portion  521   c , is installed in internal combustion engine E or its surroundings. Electromagnetic wave generator  840  generates electromagnetic waves. In this embodiment of electromagnetic wave generator  840  is a magnetron that generates 2.4-GHz-bandwidth microwaves. However, this does not restrict interpretation of composition of electromagnetic wave generator of the after-treatment apparatus for gas of the present invention. 
     Power-receiving portion  521   c  is exposed on the outer surface of valve stem  521  in exhaust valve  520 , as shown in  FIGS. 17 and 18 . Dielectric member  850  and power-feeding member  860  are in Cylinder head  300 . Dielectric member  850  is made from a ceramic and approaches power-receiving portion  521   c  at least when valve head  522  of exhaust valve  520  closes the exhaust port opening in the side of the combustion chamber. Dielectric member  850  must be made from a dielectric. Power-feeding member  860  is made from metal. Power-feeding member  860  is close to the dielectric member  850  opposite the valve stem of exhaust valve  520 . Power-feeding member  860  must be made from conductive material. The electromagnetic wave transmission method between power-feeding member  860  and power-receiving portion  521   c  via dielectric member  850  can be either electric coupling (capacitive) or magnetic coupling (dielectric). The configuration and material of power-feeding member  860  and power-receiving portion  521   c  may be selected according to the method. For example, in the case of electric coupling, power-feeding member  860  and power-receiving portion  521   c  should be conductive plates facing each other. The power feeding member  860  and the power receiving portion  521   c  may be respectively electric antenna with predefined advantage to electromagnetic waves generated by the electromagnetic wave generator  840 . In the case of magnetic coupling, power-feeding member  860  and power-receiving portion  521   c  should be conductive coils. The power feeding member  860  and the power receiving portion  521   c  may be respectively a magnetic antenna with predefined advantage to electromagnetic waves generated by the electromagnetic wave generator  840 . As a result, the electromagnetic wave generator  840  provides the power feeding member  860  with electromagnetic waves when the power feeding member  860  receives an output signal of the electromagnetic wave generator  840 . 
     As shown in  FIG. 17 , guide mounted hole  350 , which penetrates from the exhaust port  320  to the outer wall of cylinder head  300 , is installed in the cylinder head  300 . Valve guide with trunk shape made from a ceramics fits into the valve guide mounted hole  350 , allowing a hole in the valve guide  360  to serve as a guide hole  340 . Valve guide may be made from dielectric material. In valve guide  360 , a portion approaching the power-receiving portion  521   c  at least when the valve head  522  of the exhaust valve  520  closes the combustion chamber side opening of the exhaust port  320  is the dielectric member  850 . 
     The after-treatment apparatus for exhaust gas of the present invention is configured such that discharge is generated with the first electrode  812  and second electrode  813  of the discharge device  810  and the electromagnetic waves fed from the electromagnetic wave generator  840  through the electromagnetic wave transmission line  830  are radiated from the antenna  820 , while the exhaust gas remains in the combustion chamber  400  after the exhaust gas is produced during the explosion stroke. Cylinder block  100  or cylinder head  300  are earthed. The earth terminals of discharge voltage generator  950  and electromagnetic wave generator  840  are earthed. Discharge voltage generator  950  and electromagnetic wave generator  840  are controlled by controller  880 , which has a CPU, memory, and storage etc, and outputs control signals after computing input signals. Crank angle detection signals are sent from crank angle detector  890  to controller  880 . Therefore, controller  880  receives signals from crank angle detector  890  and controls the actuations of discharge device  810  and electromagnetic wave generator  840 . However, this does not restrict the control method and the composition of the input-output signals as for the after-treatment apparatus for exhaust gas of the present invention. 
     In the actuation of the internal combustion engine E, discharge is generated at the electrode  812 ,  813  of the discharge device  810  and the electromagnetic waves fed from the electromagnetic wave generator  840  through the electromagnetic wave transmission line  830  are radiated from the antenna  820 . Therefore, the plasma is generated near first electrode  812 ,  813 . This plasma receives energy of an electromagnetic waves (electromagnetic wave pulse) supplied from the antenna  820  for a given period of time. As a result, the plasma generates a large amount of OH radicals and ozone to promote the oxidation reaction etc. of the exhaust gas components. In fact electrons near these electrodes are accelerated, fly out of the plasma area, and collide with gas such as air or the air-fuel mixture in surrounding area of said plasma. The gas in the surrounding area is ionized by these collisions and becomes plasma. Electrons also exist in the newly formed plasma. These also are accelerated by the electromagnetic wave pulse and collide with surrounding gas. The gas ionizes like an avalanche and floating electrons are produced in the surrounding area by chains of these electron acceleration and collision with electron and gas inside plasma. These phenomena spread to the area around discharge plasma in sequence, then the surrounding area get into plasma state. In the result of the phenomena as mentioned above it, the volume of plasma increases. Then the electrons recombine rather than dissociate at the time when the electromagnetic wave pulse radiation is stopped. As a result, the electron density decreases, and the volume of plasma decreases as well. The plasma disappears when the electron recombination is completed. A large amount of OH radicals and ozone is generated from moisture in the gas mixture as a result of a large amount of the generated plasma, promoting the oxidation reaction etc. of the exhaust gas components. 
     In this case, oxidation reaction etc. is initiated in the combustion chamber  400  as a reactor while exhaust gas remains in the combustion chamber  400  after the exhaust gas is produced at explosion stroke. The high temperature of the exhaust gas also promotes the oxidation reactions, which increases cleanup efficiency in combination with the oxidation reaction etc. obtained by generating a large amount of OH radicals and ozone with plasma. Therefore, it is not necessary to use a rich air-to-fuel ratio or afterburning downstream of the combustion chamber, which would prevent the mileage reduction of the internal combustion engine E. 
     In addition, until the intake valves  510  open the intake ports  310  or the exhaust valves  520  open the exhaust ports  320  after generation exhaust gas by explosion stroke, the electromagnetic waves scattering from the combustion chamber  400  to outside is prevented. Moreover, the back faces of the intake valves  510  or the exhaust valves  520  prevent some electromagnetic waves from scattering from the combustion chamber  400  to the intake port  310  or the exhaust port  320  after the intake valves  510  open the intake ports  310  or the exhaust valves  510  open the exhaust ports  320 . Therefore, closed space of the combustion chamber  400  or space according to it becomes a reactor, where the oxidation reaction etc. of the exhaust gas components is stably initiated. 
     The after-treatment apparatus for exhaust gas in a combustion chamber of the present invention may be configured such that discharge is generated with the electrode of the discharge device and the electromagnetic waves fed from the electromagnetic wave generator through the electromagnetic wave transmission line are radiated from the antenna, while the exhaust gas remains in the combustion chamber after the exhaust gas is produced during the explosion stroke. Control method shown in  FIG. 5  and explained is one example. Even though there are various embodiments, the after-treatment apparatus for exhaust gas in a combustion chamber of the second embodiment is configured such that discharge is generated with the electrode  812 ,  813  of the discharge device  810  and the electromagnetic waves fed from the electromagnetic wave generator  840  through the electromagnetic wave transmission line  780  are radiated from an antenna  820 , from the time when exhaust gas is produced at the explosion stroke to the time when the intake valves  510  open the intake ports  310  or the exhaust valves  520  open the exhaust ports  320 , as the explanation using  FIG. 4 . This makes it possible that the intake valves  510  and exhaust valves  520  prevent electromagnetic waves from scattering from the combustion chamber  400  to outside. Therefore, closed space of the combustion chamber  400  becomes a reactor, where the oxidation reaction etc. of the exhaust gas components is stably initiated. 
     The after-treatment apparatus for exhaust gas in a combustion chamber of the present invention may be configured such that discharge is generated with the electrode of the discharge device and the electromagnetic waves fed from the electromagnetic wave generator through the electromagnetic wave transmission line are radiated from the antenna, while the exhaust gas remains in the combustion chamber after the exhaust gas is produced during the explosion stroke. This does not restrict the control method and the composition of the input-output signals of discharge device or electromagnetic wave generator. Even though there are various embodiments, the after-treatment apparatus for exhaust gas in a combustion chamber of the third embodiment comprises crank angle detector  890  and controller  880 . Crank angle detector  890  detects the crank angle of crank shaft  920 . Controller  880  receives the signal from this crank angle detector  890 , and controls the operation of discharge device  810  and electromagnetic wave generator  840 . This makes it possible that discharge at the electrode  812 ,  813  and the radiation of the electromagnetic waves from the antenna  820  is controlled according to the crank angle. 
     The positional relationship between the antenna and the electrodes is not restricted in the after-treatment apparatus for exhaust gas in a combustion chamber of the present invention. Even though there are various embodiments, the electrode  812 ,  813  is located close to a portion that the electric field intensity generated by the electromagnetic waves strengthens in the antenna  820  when the electromagnetic waves are fed into the antenna  820  in the after-treatment apparatus for exhaust gas in a combustion chamber of the third embodiment. This makes it possible that the electrical field intensity, due to the electromagnetic waves radiated from said portion of the antenna  820 , is stronger than the electrical field intensity of the surrounding electromagnetic waves. Therefore, the energy of the electromagnetic wave pulse is intensively supplied to the plasma generated by discharge at the electrode  812 ,  813 . As a result, a large amount of OH radicals and ozone is efficiently generated, further promoting the oxidation reaction etc. of the exhaust gas components in the area centered at the electrode  812 ,  813 . When there are multiple areas of the antenna  820  with strong electrical field intensity, the oxidation reaction etc. of the exhaust gas components at multiple areas of the combustion chamber  400  is further promoted upon the portion approaching to the electrode  812 ,  813 . 
     Moreover, the cylinder block  100  etc. which are the major structural materials can be used without modification compared with existing internal combustion engine. Additionally, the exhaust valve  520 , and the structure around this valve are remodeled. With the exception of internal combustion engine E which basically needs spark plug  810 , it may mount a discharge device on the cylinder head in internal combustion engine E that is not necessary a spark plug  810 . Therefore, it is realized to minimize the time required to design an internal combustion engine E and share many parts with existing internal combustion engines. 
     The configuration and structure of the antenna are not restricted for the after-treatment apparatus for exhaust gas of the present invention. Even though there are various embodiments, said antenna  820  forms nearly a C shape to surround the center of the valve face  522   b  of the valve head  522  as for the after-treatment apparatus in the third embodiment. One end of antenna  820  is connected to electromagnetic wave transmission line  830 . This makes the antenna  820  compact on the valve face  522   b.    
     The structure for transmitting electromagnetic waves from the electromagnetic wave generator to the electromagnetic wave transmission line is not restricted for the after-treatment apparatus for exhaust gas of the present invention. In the third embodiment of the after-treatment apparatus for exhaust gas, power-receiving portion  521   c  is exposed on the outer surface of valve stem  521  of exhaust valve  520  among such varied embodiments. The after-treatment apparatus for exhaust gas has dielectric member  850  and power-feeding member  860 . Dielectric member  850  is installed in cylinder head  300  and approaches power-receiving portion  521   c  at least when valve head  522  of exhaust valve  520  closes the exhaust port  320  opening in the side of combustion chamber. Dielectric member  850  is made from dielectric material. Power-feeding member  860  is installed in cylinder head  300 . Power-feeding member  860  is close to the dielectric member  850  opposite the valve stem  521 . Power-feeding member  860  is made from conductive material. Power-feeding member  860  is fed electromagnetic waves from electromagnetic wave generator  840 . This makes it possible to have non-contact electromagnetic wave transmission from electromagnetic wave generator  840  to electromagnetic wave transmission line  830  through power-feeding member  860 , dielectric member  850 , and power-receiving portion  521   c.    
     The structure near the guide hole is not restricted for the after-treatment apparatus for exhaust gas of the present invention. In the third embodiment of the after-treatment apparatus for exhaust gas, a valve guide mounted hole  350 , which penetrates from the exhaust port  320  to the outer wall of cylinder head  300 , is installed in the cylinder head  300  among such varied embodiments. A valve guide  360  with trunk shape, made from dielectric material, fits into the valve guide mounted hole  350  allowing a hole in the valve guide  360  to serve as a guide hole. A portion of the valve guide  360 , approaching the power-receiving portion  521   c  at least when the valve head  522  closes the combustion chamber side opening of the exhaust port  320 , is the dielectric member. This makes it possible to have non-contact electromagnetic wave transmission from electromagnetic wave generator  840  to electromagnetic wave transmission line  830  by using heretofore known mechanism for mounting the valve guide. 
     The positional relationship between the antenna and the electrode is not restricted for the after-treatment apparatus for exhaust gas of the present invention. In the third embodiment of the after-treatment apparatus for exhaust gas, first electrode  812  and second electrode  813  are located close to a portion where the electric field intensity generated by the electromagnetic waves around the valve face  522   b  of the valve head  522  becomes strong when the electromagnetic waves are fed to the antenna  820 . This makes it possible that the electromagnetic wave pulse irradiates the plasma generated by the discharge at first electrode  812  and second electrode  813  from the antenna near plasma. The energy is intensively supplied to said plasma. As a result, a large amount of OH radicals and ozone is efficiently generated, further promoting the oxidation reaction etc. 
     Next, the modification of the after-treatment apparatus for exhaust gas using a valve of the present invention will be described. This modification of the after-treatment apparatus for exhaust gas differs from the third embodiment only in the composition of exhaust valve  520 . In the exhaust valve  520  of the plasma apparatus in the third embodiment, the interior of valve stem  521  that fits into guide hole  340  is made from a dielectric or insulator as a basic portion  521   a . Moreover, a fitting portion into the guide hole  340  on the periphery of the basic portion  521   a  is made from metal as a periphery portion  521   b . In the exhaust valve  520  of the modification of the after-treatment apparatus for exhaust gas, not only basic portion  521   a  but periphery portion  521   b  are an integral structure and are made from a dielectric or insulator, as shown in  FIG. 20 . This increases the relative volume of the dielectric or insulator for the same valve stem  521  diameter. Thus, if the impedance of electromagnetic wave transmission line  830  is same level between the third embodiments and the modification, the cross-sectional area of electromagnetic wave transmission line  830  for the second embodiment will be larger, increasing the transmitting efficiency. Other functions and effects are similar to the third embodiment of the after-treatment apparatus for exhaust gas. 
     In the embodiment mentioned above, the plasma apparatus is composed by using the exhaust valve. That is, these after-treatment apparatus for exhaust gas has the antenna  820  arranged on the valve face  522   b  of the valve head  522  of the exhaust valve  520 . The electromagnetic wave transmission line  830  is installed in the valve stem  521  of the exhaust valve  520 . The electromagnetic wave generator  840  for feeding electromagnetic waves is in the power-receiving portion  521   c  which is arranged on the valve stem  521  of the exhaust valve  520 . At compression stroke when the valve head  522  of the exhaust valve  520  closes the combustion chamber side opening  321  of the exhaust port  320 , this plasma apparatus configures that discharge is generated between the electrodes of the discharge device  810 , and electromagnetic waves fed from the electromagnetic wave generator  840  through the electromagnetic wave transmission line  830  is radiated from the antenna  820 . But the present invention includes an embodiment which the after-treatment apparatus for exhaust gas is composed by using an intake valve. That is, the after-treatment apparatus for exhaust gas using an intake valve has an antenna arranged on the valve face of the valve head of the intake valve. An electromagnetic wave transmission line is installed in the valve stem of the intake valve. The electromagnetic wave generator for feeding electromagnetic waves is installed in the power-receiving portion which is arranged on the valve stem of the intake valve. At the compression stroke when the valve head of the intake valves close the combustion chamber side openings of said intake ports, Discharge is generated between the electrodes of the discharge device  810 , and electromagnetic waves fed from the electromagnetic wave generator through the electromagnetic wave transmission line are radiated from the antenna. In this case, the component of the intake valve, the antenna, the electromagnetic wave line, the power-receiving portion, the electromagnetic wave generator, the discharge device, and the electrodes of the discharge device is similar to the exhaust valve etc. of the after-treatment apparatus for exhaust gas using the exhaust valve. Functions and effects of the after-treatment apparatus for exhaust gas using the intake valve are similar to the case of said each embodiment. The antenna forms nearly a C-shaped to surround the center of the valve face. Functions and effects, in the case that one end of this antenna is connected to electromagnetic wave transmission line, are similar to the case of said each embodiment. The power-receiving portion is exposed on outer surface of said valve stem. The after-treatment apparatus for exhaust gas comprises dielectric member and power-feeding member. The dielectric member is installed in said cylinder head, and gets close to said power-receiving portion, at least when said valve head closes the combustion chamber side opening of the intake port. The dielectric member is made from dielectric. The power-feeding member is installed in the cylinder head. The power-feeding member, made from conductive, gets close to the dielectric member from the opposite side of the valve stem. Functions and effects are similar to the case of said each embodiment in the case that electromagnetic waves are supplied from the electromagnetic wave generator to the power-receiving portion. In addition, a valve guide mounted hole, which penetrates from the intake port to the outer wall of the cylinder head, in installed in the cylinder head. The valve guide with trunk shape made from a ceramics fits into the valve guide mounted hole, allowing a hole in the valve guide  360  to serve as a guide hole  340 . Functions and effects are similar to the case of said each embodiment in the case that a portion of the valve guide, approaching said power-receiving portion at least when said valve head closes the combustion chamber side opening of the intake port, is the dielectric member. Moreover, Functions and effects are similar to the case of said each embodiment in the case that the electrodes are located close to a portion that electric field intensity, generated by the electromagnetic waves in the antenna, becomes strong when the electromagnetic waves are fed to said antenna. 
     Next, the after-treatment apparatus for exhaust gas in forth embodiment will be described. In the after-treatment apparatus for exhaust gas in first embodiment, discharge devices  810 , antenna  820 , and electromagnetic wave transmission line  830  are installed in the cylinder head  300  of the members constituting the combustion chamber  400 . 
     Hereinafter, the after-treatment apparatus for exhaust gas in a combustion chamber in forth embodiment will be described.  FIGS. 21 and 22  shows the embodiment of the internal combustion engine E. The present invention targets reciprocating engines. In this embodiment, engine E is a four-cycle gasoline engine. Item  100  is the cylinder block. Cylinder block  100  contains cylinder  110 , which has an approximately circular cross section. Cylinder  110  penetrates cylinder block  100 . Piston  200 , which has an approximately circular cross section corresponding to cylinder  110 , fits into cylinder  110  and reciprocates freely. Cylinder head  300  is assembled on the anti-crankcase side of cylinder block  110 . Cylinder head  300 , piston  200 , and cylinder  110  form combustion chamber  400 . Item  910  is a connecting rod, with one end connected to piston  200  and the other end connected to crankshaft  920 , which is the output shaft. Cylinder head  300  has intake port  310 , which is a component of the intake line, and exhaust port  320 , which is a component of the exhaust line. One end of intake port  310  connects to combustion chamber  400 ; the other end is open at the outside wall of cylinder head  300 . One end of exhaust port  320  connects to combustion chamber  400 ; the other end is open at the outside wall of cylinder head  300 . The cylinder head has guide hole  330  that passes through intake port  310  to the outside wall of cylinder head  300 . Rod-shaped valve stem  511  of intake valve  510  fits into guiding hole  330  and reciprocates freely. Umbrella-shaped valve head  512 , set at the end of valve stem  511 , opens and closes the combustion chamber side opening  311  of intake port  310  at a given timing by a valve open/close mechanism having a cam and so on (not shown in the figure). Cylinder head  300  has guiding hole  340  that passes through exhaust port  320  to the outside wall of cylinder head  300 . Rod-shaped valve stem  521  of exhaust valve  520  fits into guiding hole  340  and reciprocates freely. Umbrella-shaped valve head  522 , set at the end of valve stem  521 , opens and closes the combustion chamber side opening  321  of the exhaust port  320  at a given time by the valve open/close mechanism having cam and so on (not shown in the figure). Item  810  is a spark plug installed in cylinder head  300  to expose a pair of electrodes  812 ,  813  to combustion chamber  400 . Spark plug  810  discharges at the electrodes when piston  200  is near top dead center. Therefore, four strokes (intake, compression, combustion of mixture, and exhaust of exhaust gas) occur while piston  200  reciprocates between top dead center and bottom dead center twice. However, this embodiment does not restrict the interpretation of the internal combustion engine targeted by the present invention. The present invention is also suitable for use with two-stroke internal combustion engines and diesel engines. Target gasoline engines include direct-injection gasoline engines, which create a mixture inside the combustion chamber to inject fuel into the intake air. Target diesel engines include direct-injection diesel engines, which inject fuel into the combustion chamber directly, and divided-chamber diesel engines, which inject fuel into divided chamber. Internal combustion engine E in this embodiment has four cylinders, but this does not restrict number of cylinders of the internal combustion engine targeted by the present invention. The internal combustion engine for this embodiment has two intake valves  510  and two exhaust valves  520 , but this does not restrict the number of intake or exhaust valves of the internal combustion engine targeted by the present invention. Item  700  is a gasket installed between cylinder block  100  and cylinder head  300 . 
     Said spark plug  810  also functions as a discharge device  810  of the after-treatment apparatus for exhaust gas of the present invention. This discharge device  810  is installed in the cylinder head  300 . This discharge device  810  is set on the wall of the combustion chamber  400 . This discharge device  810  comprises a connection  811  set outside of the combustion chamber  400 , a first electrode  812  electrically-connected to the connection  811 , and a second electrode  813  contacts the cylinder head  300  and connects in ground. The first electrode  812  and the second electrode  813  are placed opposite at specified interval on the discharge device  810 . Both of them are exposed to the combustion chamber  400 . The discharge device  810  is connected to a discharge voltage generator  950  which generates voltage for discharge. Here, the discharge voltage generator  950  is DC 12V power supply and a spark coil. The cylinder head  300  is earthed and the connection  811  connects to the discharge voltage generator  950 . In case of applying voltage between the cylinder head  300  and the connection  811 , discharge happens between the first electrode  812  and the second electrode  813 . As described above, it may discharge between the electrodes of the discharge device and a wall of the combustion chamber, or other earthed members without a pair of electrodes. For example, in case that the internal combustion engine is a diesel engine, it does not install a spark plug under normal circumstances. Therefore it needs to install the discharge device, having an electrode exposed to the combustion chamber, on the cylinder head. In this case, it may install the spark plug as explained above as the discharge device, and connects it to the discharge voltage generator. However the discharge device does not always need to use a spark plug, because the discharge device requires generating plasma by discharge regardless the size. The discharge device may be used for example piezo element or other device. 
     Antenna  820  is installed in cylinder head  300  to radiate electromagnetic waves to combustion chamber  400 . The wall of combustion chamber  400  in cylinder head  300  contains a hole that penetrates to the outside wall. Inside support  370  is installed near the combustion chamber side opening of this hole, and tubular outside support  380  is installed outside and continuation of the inside support  370 . Inside support  370  and outside support  380  are made from a ceramic. Both supports may be made from dielectric material or an insulator. Antenna  820 , which is made from metal, is installed in inside support  370 . However, it can be made from a conductor, dielectric or insulator, provided that electromagnetic waves are radiated well from it to the combustion chamber when they are supplied between the antenna and the earth member. Antenna  820  consists of a bar installed near the combustion chamber side opening of said hole. Antenna  820  protrudes from cylinder head  300  to combustion chamber  400 . Inside support  370  contains a bulging portion  371 . This bulging portion  371  bulges from the wall of combustion chamber  400  in cylinder head  300 , covering antenna  820 . Bulging portion  371  may be made from an insulator or dielectric. Because the bulging portion  371  forms part of inside support  370 , it is also made from a ceramic. The bulging portion may be made from different materials against inside support. For example, the length of the antenna  820  is set to a quarter of wavelength in electromagnetic waves, standing wave is generated in the antenna  820 . Thus, electrical field strength at the end of antenna  820  becomes strong. For example, the length of the antenna  820  is set to a multiple of a quarter wavelengths of the electromagnetic waves so that standing waves are generated in the antenna  820 , increasing the electrical field at multiple points, where the anti-nodes of the standing waves are generated, in the antenna  820 . Here, antenna  820  is buried inside support  370 . The solid cross-section of antenna  820  is approximately circular for its entire length. However, antenna  820  of the after-treatment apparatus of the present invention is not restricted to a circular cross-sectional shape. The first electrode  812  and the second electrode  813  are located close to a portion where the electric field intensity generated by the electromagnetic waves becomes strong in the antenna  820  when the electromagnetic waves are fed to the antenna  820 . Here, the end of antenna  820 , the first electrode  812  and the second electrode  813  are close to each other along the wall of combustion chamber  400  in cylinder head  300  at specified intervals. Thus, when electromagnetic waves are supplied between antenna  820  and cylinder head  300 , which is earthed, electromagnetic waves are radiated from antenna  820  to combustion chamber  400 . In this embodiment, antenna  820  is a rod-shaped curved monopole. However, the antenna of the after-treatment apparatus for exhaust gas in the present invention is not restricted. The antenna of the after-treatment apparatus for exhaust gas in the present invention may be dipole type, Yagi-Uda type, single wire type, loop type, phase difference feeder type, grounded type, ungrounded and perpendicular type, beam type, horizontal polarized omni-directional type, corner-reflector type, comb type or other type of linear antenna, microstrip type, planar inverted F type or other type of flat antenna, slot type, parabola type, horn type, horn reflector type, Cassegrain type or other type of solid antenna, Beverage type or other type of traveling-wave antenna, star EH type, bridge EH type or other type of EH antennas, bar type, small loop type or other type of magnetic antenna, or dielectric antenna. 
     Electromagnetic wave transmission line  830  is installed in cylinder head  300 . One end of electromagnetic wave transmission line  830  is connected to antenna  820 , and the other end is covered by a dielectric that penetrates and stretches to the outside wall of cylinder head  300 . Electromagnetic wave transmission line  830  is installed in outside support  380 , and is made from copper wire. Electromagnetic wave transmission line  830  may also be made from any conductor, insulator, or dielectric, as long as electromagnetic waves are transmitted well to antenna  820  when they are supplied between antenna  820  and the earthed member. A possible variation is an electromagnetic wave transmission line that consists of a waveguide made from a conductor or dielectric. Here, electromagnetic wave transmission line  830  is buried in outside support  380 , and passed through outside support  380 . One end of the electromagnetic wave transmission line  830  is connected to said antenna  820  and the other end is extracted from the outside wall of cylinder head  300  to outside. Thus, when electromagnetic waves are supplied between electromagnetic wave transmission line  830  and cylinder head  300  that is the earth member, they are introduced into antenna  820 . 
     Electromagnetic wave generator  840 , which supplies electromagnetic waves to electromagnetic wave transmission line  830 , is installed in internal combustion engine E or its surroundings. Electromagnetic wave generator  840  generates electromagnetic waves. In this embodiment of electromagnetic wave generator  840  is a magnetron that generates 2.45-GHz-bandwidth microwaves. However, this does not restrict interpretation of composition of electromagnetic wave generator of the after-treatment apparatus for gas of the present invention. 
     As shown in  FIG. 21 , antenna  820  stretches from the outside wall of cylinder head  300  to combustion chamber  400  along the pass of hole. Then the antenna  820  turns off L-shaped. The end of antenna  820  aims at the first electrode  812  and the second electrode  813  of discharge device  810  along the wall of combustion chamber  400  in cylinder head  300 . In addition, as shown in  FIG. 22 , the first electrode  812  and the second electrode  813  are placed in the vicinity of the center of the combustion chamber  400 , when viewed from the direction of reciprocation of the piston. Antenna  820  is installed from the first electrode  812  or the second electrode  813  to a portion corresponding to a cylinder wall on the cylinder head. Two exhaust valves  520  are installed in this embodiment, although multiple exhaust values  520  may be used. The first electrode  812 , the second electrode  813 , and antenna  820  are arranged so that a virtual line, which connects the first electrode  812  or the second electrode  813  and the antenna  820 , pass through two adjoining ports of two inlet ports  310  and two exhaust ports  320  in the cylinder head  300 . 
     The after-treatment apparatus for exhaust gas in a combustion chamber of the present invention may be configured such that discharge is generated with the first electrode  812  and second electrode  813  of the discharge device  810  and the electromagnetic waves fed from the electromagnetic wave generator through the electromagnetic wave transmission line  830  are radiated from the antenna  820 , while the exhaust gas remains in the combustion chamber after the exhaust gas is produced during the explosion stroke. Cylinder head  300  is earthed. The earth terminals of discharge voltage generator  950  and electromagnetic wave generator  840  are earthed. Discharge voltage generator  950  and electromagnetic wave generator  840  are controlled by controller  880 , which has a CPU, memory, and storage etc, and outputs control signals after computing input signals. A signal line from crank angle detector  890  for detecting crank angle of crankshaft  920  is connected to control unit  880 . Crank angle detection signals are sent from crank angle detector  890  to controller  880 . Therefore, controller  880  receives signals from crank angle detector  890  and controls the actuations of discharge device  810  and electromagnetic wave generator  840 . However, this does not restrict the control method and the composition of the input-output signals as for after-treatment apparatus for exhaust gas of the present invention. 
     Therefore, at the actuation of the internal combustion engine E, discharge is generated between the electrode  812 ,  813  of said discharge device  810  and the electromagnetic waves fed from the electromagnetic wave generator  840  through the electromagnetic wave transmission line  830  are radiated from the antenna  820 . Therefore, plasma is generated near the electrode  812 ,  813  by discharge. This plasma receives energy of an electromagnetic waves (electromagnetic wave pulse) supplied from the antenna  820  for a given period of time. As a result, the plasma generates a large amount of OH radicals and ozone to promote the oxidation reaction etc. of the exhaust gas components. In fact electrons near the electrode are accelerated, fly out of the plasma area, and collide with gas such as air or the air-fuel mixture in surrounding area of said plasma. The gas in the surrounding area is ionized by these collisions and becomes plasma. Electrons also exist in the newly formed plasma. These also are accelerated by the electromagnetic wave pulse and collide with surrounding gas. The gas ionizes like an avalanche and floating electrons are produced in the surrounding area by chains of these electron acceleration and collision with electron and gas inside plasma. These phenomena spread to the area around discharge plasma in sequence, then the surrounding area get into plasma state. In the result of the phenomena as mentioned above it, the volume of plasma increases. Then the electrons recombine rather than dissociate at the time when the electromagnetic wave pulse radiation is stopped. As a result, the electron density decreases, and the volume of plasma decreases as well. The plasma disappears when the electron recombination is completed. A large amount of OH radicals and ozone is generated from moisture in the gas mixture as a result of a large amount of the generated plasma, promoting the oxidation reaction etc. of the exhaust gas components. 
     In this case, oxidation reaction etc. is initiated in the combustion chamber as a reactor while exhaust gas remains in the combustion chamber after the exhaust gas is produced at explosion stroke. The high temperature of the exhaust gas also promotes the oxidation reactions, which increases cleanup efficiency in combination with the oxidation reaction etc. obtained by generating a large amount of OH radicals and ozone with plasma. Therefore, it is not necessary to use a rich air-to-fuel ratio or afterburning downstream of the combustion chamber, which would prevent the mileage reduction of the internal combustion engine. 
     In addition, until the intake valves  510  open the intake ports  310  or the exhaust valves  520  open the exhaust ports  320  after generation exhaust gas by explosion stroke, the electromagnetic waves scattering from the combustion chamber  400  to outside is prevented. Moreover, the back faces of the intake valves  510  or the exhaust valves  520  prevent some electromagnetic waves from scattering from the combustion chamber  400  to the intake port  310  or the exhaust port  320  after the intake valves  510  open the intake ports  310  or the exhaust valves  510  open the exhaust ports  320 . Therefore, closed space of the combustion chamber  400  or space according to it becomes a reactor, where the oxidation reaction etc. of the exhaust gas components is stably initiated. 
     The after-treatment apparatus for exhaust gas in a combustion chamber of the present invention may be configured such that discharge is generated with the electrode of the discharge device and the electromagnetic waves fed from the electromagnetic wave generator through the electromagnetic wave transmission line are radiated from the antenna, while the exhaust gas remains in the combustion chamber after the exhaust gas is produced during the explosion stroke. Control method shown in  FIG. 5  and explained is one example. Even though there are various embodiments, the after-treatment apparatus for exhaust gas in a combustion chamber of the first embodiment is configured such that discharge is generated with the electrode  812 ,  812  of the discharge device  810  and the electromagnetic waves fed from the electromagnetic wave generator  840  through the electromagnetic wave transmission line  830  are radiated from an antenna  820 , from the time when exhaust gas is produced at the explosion stroke to the time when the intake valves  510  open the intake ports  310  or the exhaust valves  520  open the exhaust ports  320 , as the explanation using  FIG. 4 . This makes it possible that the intake valves  510  and exhaust valves  520  prevent electromagnetic waves from scattering from the combustion chamber  400  to outside. Therefore, closed space of the combustion chamber  400  becomes a reactor, where the oxidation reaction etc. of the exhaust gas components is stably initiated. 
     The after-treatment apparatus for exhaust gas in a combustion chamber of the present invention may be configured such that discharge is generated with the electrode of the discharge device and the electromagnetic waves fed from the electromagnetic wave generator through the electromagnetic wave transmission line are radiated from the antenna, while the exhaust gas remains in the combustion chamber after the exhaust gas is produced during the explosion stroke. This does not restrict the control method and the composition of the input-output signals of discharge device or electromagnetic wave generator. Even though there are various embodiments, the after-treatment apparatus for exhaust gas in a combustion chamber of the first embodiment comprises crank angle detector  890  and controller  880 . Crank angle detector  890  detects the crank angle of crank shaft  920 . Controller  880  receives the signal from this crank angle detector  890 , and controls the operation of discharge device  810  and electromagnetic wave generator  840 . This makes it possible that discharge at the electrode  812 ,  813  and the radiation of the electromagnetic waves from the antenna  820  is controlled according to the crank angle. 
     The positional relationship between the antenna and the electrodes is not restricted in the after-treatment apparatus for exhaust gas in a combustion chamber of the present invention. Even though there are various embodiments, the electrode  812 ,  813  is located close to a portion that the electric field intensity generated by the electromagnetic waves strengthens in the antenna  820  when the electromagnetic waves are fed into the antenna  820  in the after-treatment apparatus for exhaust gas in a combustion chamber of the first embodiment. This makes it possible that the electrical field intensity, due to the electromagnetic waves radiated from said portion of the antenna  820 , is stronger than the electrical field intensity of the surrounding electromagnetic waves. Therefore, the energy of the electromagnetic wave pulse is intensively supplied to the plasma generated by discharge at the electrode  812 ,  813 . As a result, a large amount of OH radicals and ozone is efficiently generated, further promoting the oxidation reaction etc. of the exhaust gas components in the area centered at the electrode  812 ,  813 . When there are multiple areas of the antenna  820  with strong electrical field intensity, the oxidation reaction etc. of the exhaust gas components at multiple areas of the combustion chamber  400  is further promoted upon the portion approaching to the electrode  812 ,  813 . 
     In this case, the cylinder block etc. which are the major structural materials can be used without modification compared with existing internal combustion engine. And the cylinder head is remodeled. With the exception of internal combustion engine E which basically needs spark plug  810 , it may mount a discharge device on the cylinder head in internal combustion engine that is not necessary a spark plug. Therefore, it is realized to minimize the time required to design an internal combustion engine and share many parts with existing internal combustion engines. In addition, the bulging portion reduces the heat load which affects the antenna in the combustion chamber and the fatigue of the antenna due to mechanical vibration. 
     In the after-treatment apparatus for exhaust gas of the present invention, the antenna may be installed to protrude from the cylinder head into the combustion chamber. The direction of the antenna tip is not restricted. Though there are various embodiments, the tip direction of the antenna  820  aims at the first electrode  812  and the second electrode  813  of the discharge device  810  in the after-treatment apparatus for exhaust gas of the present invention. This allows the plasma generated by the discharge at the electrode to radiate electromagnetic wave pulses from the antenna  820  intensively. As a result, the plasma is supplied energy intensively, which generates a large amount of OH radicals and ozone efficiently, further promoting the oxidation reaction etc. 
     In the after-treatment apparatus for exhaust gas of the present invention, the electrodes of the discharge device, installed in the cylinder head, may be exposed to the combustion chamber. The position of the electrodes is not restricted. Moreover, the antenna may be installed to protrude from the cylinder head into the combustion chamber. The position of the antenna is not restricted. Though there are various embodiments, the first electrode  812  and the second electrode  813  are placed in the vicinity of the center of the combustion chamber  400  when viewed from the direction of reciprocation of the piston in the after-treatment apparatus for exhaust gas of the present invention. Said antenna  820  is installed between the first electrode  812  or the second electrode  813  and the portion corresponding to the cylinder wall. This allows the plasma generated by the discharge near the first electrode  812  and the second electrode  813  to receive energy from the electromagnetic wave pulse radiated from the antenna  820 , increasing its volume. Antenna  820  is installed between the first electrode  812  or the second electrode  813  and the portion corresponding to the cylinder wall. Hence, a large amount of plasma is distributed from the first electrode  812  or the second electrode  813  to the portion corresponding to the cylinder wall, and the combustion flame is spread from the first electrode  812  or the second electrode  813  to the cylinder wall by the OH radicals and ozone generated by the plasma. 
     In the after-treatment apparatus for exhaust gas of the present invention, relative position of the electrodes and the antenna is not restricted. Though there are various embodiments, the first electrode  812 , the second electrode  813 , and antenna  820  are arranged so that a virtual line, which connects the first electrode  812  or the second electrode  813  and the antenna  820 , pass through two adjoining ports of two inlet ports  310  and two exhaust ports  320  in the cylinder head  300  in the after-treatment apparatus of first embodiment. This makes possible that the antenna  820  is allocated effectively by using plane between exhaust ports  320 . 
     In the after-treatment apparatus for exhaust gas of the present invention, the positional relationship between the antenna and the electrodes are not restricted. Though there are various embodiments, the first electrode  812  and the second electrode  813  are located close to a portion where the electric field intensity generated by the electromagnetic waves becomes strong in the antenna  820  when the electromagnetic waves are fed to the antenna  820  in the after-treatment apparatus for exhaust gas of first embodiment. This makes it possible that the electromagnetic wave pulse irradiates the plasma, generated by the discharge at the first electrode  812  and the second electrode  813 , from the antenna  820  near plasma. The energy is intensively supplied to said plasma. As a result, a large amount of OH radicals and ozone is efficiently generated, further promoting the oxidation reaction etc. 
     Next, the modification of the after-treatment apparatus for exhaust gas of the present invention will be described. The modification of the after-treatment apparatus for exhaust gas is different from the fourth embodiment in only number and alignment of the antenna  820 . The after-treatment apparatus for exhaust gas of the fourth embodiment installs one antenna  820 . On the other hand, the modification of the after-treatment apparatus for exhaust gas, shown in  FIG. 23  installs multiple antennas  820  which are same as the antenna  820  in the first embodiment. Said first electrode  812  and second electrode  813  are placed in the vicinity of the center of the combustion chamber.  400  when viewed from the direction of reciprocation of the piston  200 . Moreover said multiple antennas  820  queue up from said first electrode  812  or second electrode  813  toward the portion corresponding to the cylinder wall, when viewed from the direction of reciprocation of the piston  200 . Here, three antennas  820  queue up respectively along four directions radiated from the center, when viewed from the direction of reciprocation of the piston  820 . The angle between two directions next to each other is almost 90 degrees. Moreover, the first electrode  812 , the second electrode  813 , and antennas  820  are arranged so that a virtual line, which connects the first electrode  812  or the second electrode  813  and the antenna  820 , pass through two adjoining ports of two inlet ports  310  and two exhaust ports  320  in the cylinder head  300 . 
     In the modification of the after-treatment apparatus for exhaust gas of the present invention, said first electrode  812  and second electrode  813  are placed in the vicinity of the center of the combustion chamber  400 , when viewed from the direction of reciprocation of the piston. Multiple antennas queue up from the first electrode  812  or the second electrode  813  toward the portion corresponding to a cylinder wall. This allows the plasma generated by the discharge near the first electrode  812  and the second electrode  813  to receive energy from the electromagnetic wave pulse radiated from the antennas  820 , increasing its volume. The antennas  820  queue up from the first electrode  812  or the second electrode  813  to the portion corresponding to the cylinder wall. Hence, a large amount of plasma is distributed from the first electrode  812  or the second electrode  813  to the portion corresponding to the cylinder wall, and the combustion flame is spread from the electrodes to the cylinder wall by the OH radicals and ozone generated by the plasma. 
     In the modification of the after-treatment apparatus for exhaust gas of the plasma apparatus of the present invention, the first electrode  812 , the second electrode  813 , and antennas  820  are arranged so that a virtual line, which connects the first electrode  812  or the second electrode  813  and the antenna  820 , pass through two adjoining ports of two inlet ports  310  and two exhaust ports  320  in the cylinder head  300 . This makes possible that the antennas are allocated effectively by using plane between ports. Other functions and effects are similar to the case of the plasma apparatus in the fourth embodiment of the after-treatment apparatus for exhaust gas. 
     In the modification of the after-treatment apparatus for exhaust gas of the present invention, a pair of the electrodes or a pair of the electrode and the earth member may as well be covered with a dielectric. In this case, the dielectric-barrier discharge is generated by voltage applied between the electrodes or between the electrode and the earth member. The dielectric-barrier discharge is restricted because charges are accumulated in the surface of the dielectric covering the electrode or the earth member. Therefore, the discharge is generated on a very small scale over a very short period of time. Thermalization does not occur in the area surrounding the discharge because the discharge is terminated after a short period of time. Therefore, the gas temperature rise due to the discharge between the electrodes is reduced, which reduces the amount of NOx produced by the internal combustion engine. 
     The material that installs the electromagnetic wave transmission line changes according to the material that installs the antenna, and becomes the cylinder block or a cylinder head. 
     The present invention includes some embodiments that combine the characteristics of the embodiments described above. Moreover, the embodiments described above are only examples of the after-treatment apparatus for exhaust gas in a combustion chamber of the present invention. Thus, the description of these embodiments does not restrict interpretation of the after-treatment apparatus for exhaust gas in a combustion chamber of the present invention.