Plasma generation device

The plasma generation device 30 is provided with a high frequency generation device 37 that generates a high frequency wave, and a high frequency radiator 15 that radiates the high frequency wave outputted from the high frequency generation device 37 to a target space 10, and generates plasma by supplying energy of the high frequency wave to the target space 10. In the plasma generation device 30, the high frequency generation device 37 is provided with an oscillator 41 that oscillates a high frequency wave, and an amplifier 42 that amplifies and outputs the high frequency wave oscillated by the oscillator 41 to the high frequency radiator 15. In the high frequency generating device 37 the amplifier 42 alone is integrated with the high frequency radiator 15, from among the oscillator 41 and the amplifier 42.

TECHNICAL FIELD

The present invention relates to a plasma generation device that generates plasma by supplying a high frequency wave to a target space.

BACKGROUND ART

Conventionally, there is known a plasma generation device that generates plasma by supplying a high frequency wave to a target space. For example, Patent Document 1 discloses this type of a plasma generation device.

Patent Document 1 discloses a high frequency ignition plug that generates free plasma in air fuel mixture using an electric field structure protruding in a combustion chamber. A high frequency generator is used to generate a microwave, which is supplied to a high frequency ignition plug via an amplifier.

PATENT DOCUMENTS

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

In this type of a plasma generation device, electric power loss decreases as the length of a transmission line between a high frequency generation device and a high frequency radiator decreases. However, if a space in the vicinity of a location where the high frequency radiator is installed is limited, for example, in a case in which the high frequency radiator is installed on an engine, it is sometimes impossible to install the whole of the high frequency generation device in the vicinity of the high frequency radiator.

The present invention has been made in view of the above described problem, and it is an object of the present invention to provide a plasma generation device that generates plasma by supplying a high frequency wave to a target space, wherein electric power loss can be reduced in a transmission line between a high frequency generation device and a high frequency radiator, even in a case in which a space in the vicinity of a location where the high frequency radiator is installed is limited.

Means for Solving the Problems

In accordance with a first aspect of the present invention, there is provided a plasma generation device including a high frequency generation device that generates a high frequency wave, and a high frequency radiator that radiates the high frequency wave outputted from the high frequency generation device to a target space. The plasma generation device generates plasma by supplying energy of the high frequency wave to the target space from the high frequency radiator. In the plasma generation device, the high frequency generation device includes an oscillator that oscillates the high frequency wave, and an amplifier that amplifies the high frequency wave oscillated by the oscillator and outputs the high frequency wave thus amplified to the high frequency radiator. From among the oscillator and the amplifier, the amplifier alone is integrated with the high frequency radiator.

According to the first aspect of the present invention, from among the oscillator and the amplifier, the amplifier alone is integrated with the high frequency radiator. Since the amplifier and the high frequency radiator are integrated with each other, it is possible to shorten the transmission line between the amplifier and the high frequency radiator. In comparing a transmission line between the oscillator and the amplifier and the transmission line between the amplifier and the high frequency radiator, the latter is higher than the former in electric power loss per unit length since the latter transmits a larger amount of high frequency power than the former. According to the first aspect of the present invention, it is possible to shorten the transmission line relatively high in electric power loss by limiting parts of the high frequency generation device to be integrated with the high frequency radiator to the amplifier alone.

In accordance with a second aspect of the present invention, in addition to the feature of the first aspect of the present invention, the amplifier includes a plurality of stages of amplifying elements. From among the plurality of stages of amplifying elements, a downstream amplifying element is integrated with the high frequency radiator.

According to the second aspect of the present invention, in a case in which the amplifier alone, from among the oscillator and the amplifier, is integrated with the high frequency radiator, not the whole of the amplifier but apart of the amplifier is integrated with the high frequency radiator. From among the plurality of stages of amplifying elements, the downstream amplifying element alone is integrated with the high frequency radiator. Therefore, it is possible to shorten the transmission line between the amplifier and the high frequency radiator.

In accordance with a third aspect of the present invention, in addition to the feature of either the first or the second aspect of the present invention, the high frequency radiator is an ignition plug having a tip end side formed with a discharge gap and exposed to the target space.

In accordance with a fourth aspect of the present invention, in addition to the feature of the third aspect of the present invention, the ignition plug includes, separately from electrodes forming the discharge gap, an antenna for radiating high frequency waves to the target space.

In accordance with a fifth aspect of the present invention, in addition to the feature of either the third or the fourth aspect of the present invention, there is provided an ignition coil that outputs to the ignition plug a high voltage pulse for generating a discharge at the discharge gap. The amplifier is integrated with an ignition unit in which the ignition coil and the ignition plug are integrated.

According to the fifth aspect of the present invention, the amplifier is integrated with the ignition unit in which the ignition coil and the ignition plug (high frequency radiator) are integrated. In a case in which the amplifier includes the plurality of stages of amplifying elements, from among the plurality of stages of amplifying elements, the downstream amplifying element alone is integrated with the ignition unit.

In accordance with a sixth aspect of the present invention, in addition to the feature of the fifth aspect of the present invention, there is provided a mixer that is integrated with the ignition coil, mixes the high voltage pulse generated by the ignition coil and the high frequency wave amplified by the amplifier, and outputs it to the ignition plug. The amplifier is attached to the mixer, and integrated with the ignition unit via the mixer.

According to the sixth aspect of the present invention, the high voltage pulse and the amplified high frequency wave are mixed by the mixer and supplied to the ignition plug. The amplifier is integrated via the mixer with the high frequency radiator of the ignition unit.

In accordance with a seventh aspect of the present invention, in addition to the feature of any one of the first to sixth aspects of the present invention, a plurality of the high frequency radiators are provided, and a plurality of the amplifiers are provided corresponding to the high frequency radiators. The amplifiers are integrated with the respective high frequency radiators, and a high frequency switch is provided that switches a supply destination of the high frequency wave outputted from the oscillator, from among the plurality of amplifiers.

According to the seventh aspect of the present invention, the amplifiers are respectively integrated with the plurality of high frequency radiators. The high frequency wave outputted from the oscillator is supplied to one of the high frequency radiators, which is selected by the high frequency switch to be the supply destination of the high frequency wave. According to the seventh aspect of the present invention, even if the oscillators are less in number than the amplifiers and the high frequency radiators, it is possible to selectively radiate the high frequency wave from the plurality of high frequency radiators.

In accordance with an eighth aspect of the present invention, in addition to the feature of the second aspect of the present invention, there are provided a plurality of the high frequency radiators, a plurality of the downstream amplifying elements are provided corresponding to the high frequency radiators and the downstream amplifying elements are integrated with the respective high frequency radiators, and a high frequency switch is provided that switches a supply destination of the high frequency wave outputted from an upstream amplifying element from among the plurality of downstream amplifying elements.

According to the eighth aspect of the present invention, the downstream amplifying elements are respectively integrated with the plurality of high frequency radiators. The high frequency wave outputted from the upstream amplifying element is supplied through one of the downstream amplifying elements, which is selected by the high frequency switch as the supply destination of the high frequency wave, to the corresponding high frequency radiator. According to the eighth aspect of the present invention, even if the oscillators and the upstream amplifying elements are less in number than the high frequency radiators, it is possible to selectively radiate the high frequency wave from the plurality of high frequency radiators.

In accordance with a ninth aspect of the present invention, in addition to the feature of any one of the first to eighth aspects of the present invention, there is provided a power circuit that provides power for high frequency wave to the high frequency generation device. The oscillator is accommodated in the same casing as the power circuit.

According to the ninth aspect of the present invention, the oscillator is accommodated in the same casing as the power circuit.

In accordance with a tenth aspect of the present invention, in addition to the feature of any one of the first to ninth aspects of the present invention, the amplifier is integrated with the high frequency radiator in a state being accommodated in a metal casing for preventing the high frequency wave from leaking outside. Heat generated in the amplifier is released outside via the metal casing.

According to the tenth aspect of the present invention, the amplifier dissipates heat to the outside utilizing its own metal casing.

Effect of the Invention

According to the present invention, apart of the high frequency generation device to be integrated with the high frequency radiator is limited to the amplifier, thereby shortening the transmission line between the amplifier and the high frequency radiator, where electric power loss is relatively high. Since a part to be integrated with the high frequency radiator is limited to the amplifier, it is possible to avoid a unit, in which the high frequency generation device is integrated with the high frequency radiator, from increasing in size. Accordingly, even if an installation space in the vicinity of a space where the high frequency radiator is to be installed is small, it is possible to reduce electric power loss in the transmission line between the high frequency generation device and the high frequency radiator.

Furthermore, according to the second aspect of the present invention, a part to be integrated with the high frequency radiator is limited to the downstream amplifying element from among the amplifier of the high frequency generation device. Accordingly, it is further possible to avoid a unit, in which the amplifier is integrated with the high frequency radiator, from increasing in size.

Furthermore, according to the seventh and eighth aspects of the present invention, a high frequency switch is provided, thereby enabling to selectively emit the high frequency wave from the plurality of high frequency radiators, even if the oscillators are fewer in number than the high frequency radiators. Accordingly, it is possible to simplify the high frequency generation device in comparison to a case in which oscillators are provided individually in correspondence with the high frequency radiators.

Furthermore, according to the ninth aspect of the present invention, since the oscillator is accommodated in the same casing as the power circuit, it is possible to simplify the structure which accommodates the oscillator and the power circuit.

Furthermore, according to the tenth aspect of the present invention, since the amplifier dissipates heat to the outside utilizing the metal casing, which accommodates the amplifier itself, it is possible to simplify heat dissipation parts of the amplifier.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following, a detailed description will be given of the embodiment of the present invention with reference to drawings. It should be noted that the following embodiment is a mere example that is essentially preferable, and is not intended to limit the scope of the present invention, applied field thereof, or application thereof.

The present embodiment is directed to a plasma generation device30according to the present invention. The plasma generation device30constitutes an ignition device that ignites air fuel mixture in a combustion chamber10of an internal combustion engine20by causing a spark discharge by an ignition plug15to absorb energy of an electromagnetic wave (microwave), thereby generating non-equilibrium plasma. The plasma generation device30is merely one example of the present invention. Firstly, the internal combustion engine20will be described hereinafter before the plasma generation device30is described in detail.

<Construction of Internal Combustion Engine>

The internal combustion engine20according to the present embodiment is constituted by a reciprocating engine, in which a piston23reciprocates. As shown inFIG. 1, the internal combustion engine20is provided with a cylinder block21, a cylinder head22, and pistons23. The cylinder block21is formed with a plurality of cylinders24each having a circular cross section.

Inside of each cylinder24, the piston23is slidably mounted. The piston23is connected to a crankshaft (not shown) via a conrod (connecting rod, not shown). The crankshaft is rotatably supported by the cylinder block21. While the piston23reciprocates in each cylinder24in an axial direction of the cylinder24, the conrod converts the reciprocal movement of the piston23into rotational movement of the crankshaft.

The cylinder head22is placed on the cylinder block21, and a gasket18intervenes between the cylinder block21and the cylinder head22. The cylinder head22partitions the combustion chamber10along with the cylinder24and the piston23. The cylinder head22is provided for each cylinder24with one ignition plug15. The ignition plug15is fixed to a plug mounting hole19formed on the cylinder head22.

The cylinder head22is formed with one or more intake ports25and one or more exhaust ports26for each cylinder24. The intake port25is provided with an intake valve27for opening and closing an opening part of the intake port25, and an injector29(fuel injection device) that injects fuel. On the other hand, the exhaust port26is provided with an exhaust valve28for opening and closing an opening part of the exhaust port26. According to the present embodiment, a nozzle29aof the injector29is exposed to the intake port25, and the fuel injected from the injector29is supplied to an air flowing in the intake port25. Air fuel mixture, in which the fuel has been mixed with the air in advance, is introduced to the combustion chamber10.

<Construction of Plasma Generation Device>

As shown inFIG. 2, the plasma generation device30is provided with a discharge device31that causes a discharge in the combustion chamber10(target space), an electromagnetic wave oscillation device37(high frequency generation device) that oscillates an electromagnetic wave, a power circuit for electromagnetic wave36that supplies power to the electromagnetic wave oscillation device37, and an electromagnetic wave radiator15(high frequency radiator) that radiates the electromagnetic wave oscillated by the electromagnetic wave oscillation device37to the combustion chamber10. The plasma generation device30generates non-equilibrium plasma in the combustion chamber10by causing the discharge device31to discharge, as well as radiating an electromagnetic wave using the electromagnetic wave oscillation device37and the electromagnetic wave radiator15.

The plasma generation device30is connected to an electronic control unit32(sometimes referred to as “ECU”) for controlling the internal combustion engine20. The plasma generation device30is controlled by the electronic control unit32.

The discharge device31is provided with an ignition plug15having a tip end side, which is formed with a discharge gap, being exposed to the combustion chamber10, and an ignition coil35that generates a high voltage pulse to be applied to the ignition plug15. The ignition plug15and the ignition coil35are integrated with each other to collectively constitute an ignition unit40. The discharge device31is provided with ignition units40of the same number as that of the cylinders24.

In the present embodiment, the plasma generation device30further includes a mixer38. There are provided a plurality of the mixers38for the respective cylinders24of the internal combustion engine20. Each mixer38receives the high voltage pulse outputted from the ignition coil35and the electromagnetic wave outputted from the electromagnetic wave oscillation device37at respectively different input terminals, and outputs the high voltage pulse and the electromagnetic wave from the same output terminal to the ignition plug15. The mixer38is configured so as to be capable of mixing the high voltage pulse and the electromagnetic wave. In the present embodiment, the ignition plug15functions as the electromagnetic wave radiator.

The ignition coil35is connected to the electronic control unit32at an input terminal thereof, and connected to the mixer38at an output terminal thereof. The ignition coil35is connected to a vehicle battery (not shown) as well. Upon receiving a high-voltage-output signal from the electronic control unit32, the ignition coil35outputs a high voltage pulse to the mixer38.

The power circuit for electromagnetic wave36is connected to the electronic control unit32at an input terminal thereof, and connected to the electromagnetic wave oscillation device37at an output terminal thereof. The power circuit for electromagnetic wave36is connected to the vehicle battery as well. Upon receiving an electromagnetic-wave-output signal from the electronic control unit32, the power circuit for electromagnetic wave36, supplies power to the electromagnetic wave oscillation device37.

The electromagnetic wave oscillation device37includes a semiconductor element (solid state element), and is configured to output an electromagnetic wave (microwave) of 2.45 GHz, for example. The electromagnetic wave oscillation device37is provided with an oscillator41that oscillates the electromagnetic wave, and an amplifier42that amplifies the electromagnetic wave oscillated by the oscillator41and outputs the high frequency wave thus oscillated to the ignition plug15(electromagnetic wave radiator). While the electromagnetic wave oscillation device37is provided with one single oscillator41, the electromagnetic wave oscillation device37is provided with a plurality of the amplifiers42for respective ignition plugs15as well. The amplifiers42are integrated with the respective corresponding ignition plugs15. The plasma generation device30is provided with a high frequency switch60that switches from one amplifier42to another amplifier42, to which the electromagnetic wave outputted from the oscillator41is supplied.

The oscillator41is provided with an oscillating element (such as a field effect transistor) configured by a semiconductor element. The oscillator41is accommodated in the same casing39as that of the power circuit for electromagnetic wave36. The oscillator41is connected to the power circuit for electromagnetic wave36at an input terminal thereof, and connected to the high frequency switch60at an output terminal thereof via a coaxial cable. Upon receiving power from the power circuit for electromagnetic wave36, the oscillator41outputs an electromagnetic wave of low power to the high frequency switch60. The high frequency switch60outputs the electromagnetic wave received from the oscillator41to one of the amplifiers42selected from among the plurality of amplifiers42.

The amplifier42includes an amplifying element43(such as a field effect transistor) configured by a semiconductor element. The amplifying element43is attached to a circuit board44. The amplifying element43includes a wide bandgap semiconductor element such as silicone carbide, gallium nitride, and/or the like. The amplifier42is connected to the power circuit for electromagnetic wave36and the high frequency switch60at respective input terminals thereof, and connected to the mixer38at an output terminal thereof. The amplifier42is further connected to the electronic control unit32. The amplifier42, which have been switched to under control of the electronic control unit32, amplifies the electromagnetic wave inputted from the high frequency switch60and outputs a large current of the electromagnetic wave to the mixer38.

In each ignition unit40, the amplifier42is attached to the mixer38, and integrated with the ignition coil35via the mixer38. The amplifier42is also integrated with the ignition plug15via the mixer38.

The mixer38is configured so as to be capable of mixing the high voltage pulse and the electromagnetic wave. The mixer38is connected to a central electrode15aof the ignition plug15at an output terminal thereof. The high voltage pulse outputted from the ignition coil35and the electromagnetic wave amplified by the amplifier42are supplied to the ignition plug15.

As shown inFIGS. 2 and 3, each ignition unit40is a unit, in which the ignition coil35, the ignition plug15, the mixer38, and the amplifier42are integrated. In each ignition unit40, the mixer38is formed in a cylindrical shape. The mixer38is integrated with the ignition coil35at one end thereof, and integrated with the ignition plug15at the other end thereof.

In each ignition unit40, an input terminal50of the ignition coil35and an input terminal51of the amplifier42are attached on the same side of the ignition unit40. Inside of each ignition unit40, the output terminal of the ignition coil35is connected to a first input terminal of the mixer38, and the output terminal of the amplifier42is connected to a second input terminal of the mixer38.

The output terminal of the mixer38is attached to the other end of the mixer38. Each ignition unit40fits in a plug mounting hole19on a side of the output terminal of the mixer38in a state such that the output terminal of the mixer38is connected to the central electrode15aof the ignition plug15.

In the ignition unit40, the amplifier42is integrated on an outer peripheral surface of the mixer38. The amplifier42is accommodated in a metal casing45of a box shape that is fixed to the outer peripheral surface of the mixer38via a circuit board44. The metal casing45prevents the electromagnetic wave amplified by the amplifier42from leaking. A first cooling member46, which is made of metal and abutting the amplifying element43, is attached to the metal casing45. The first cooling member46abuts the metal casing45. Heat generated in the amplifying element43is transferred to the metal casing45via the first cooling member46, and released in the air in contact with the metal casing45. The amplifier42dissipates heat to the outside utilizing the metal casing45. Furthermore, a second cooling member47adapted to increase the amount of heat transfer of the heat, which is transferred from the amplifier42, is attached to the metal casing45.

<Operation of Plasma Generation Device>

The operation of the plasma generation device30and the electronic control unit32will be described hereinafter in association with the operation of the internal combustion engine20. The internal combustion engine20performs plasma ignition operation of generating plasma in each cylinder24by means of the plasma generation device30.

In the internal combustion engine20during the plasma ignition operation, the intake valve27is opened immediately before the piston23reaches the top dead center, and the intake stroke starts. Immediately after the piston23passes the top dead center, the exhaust valve28is closed, and the exhaust stroke ends. Immediately after the exhaust stroke ends, the electronic control unit32outputs an injection signal to the injector29to cause the injector29to inject fuel.

Immediately after the piston23passes the bottom dead center, the intake valve27is closed, and the intake stroke ends. After the intake stroke ends, a compression stroke of compressing the air fuel mixture in the combustion chamber10starts. During the compression stroke, immediately before the piston23reaches the top dead center, the electronic control unit32outputs a high-voltage-output signal to the ignition coil35. As a result thereof, a high voltage pulse that has been boosted in the ignition coil35is outputted to the mixer38.

Also, during the compression stroke, immediately before the piston23reaches the top dead center, the electronic control unit32outputs an electromagnetic-wave-output signal to the power circuit for electromagnetic wave36. The electronic control unit32outputs the electromagnetic-wave-output signal before the high voltage pulse is outputted from the ignition coil35. As a result thereof, power is supplied from the power circuit for electromagnetic wave36to the oscillator41, and the oscillator41outputs an electromagnetic wave.

Furthermore, the electronic control unit32outputs a switch signal to the high frequency switch60, thereby setting the supply destination of the electromagnetic wave, from among the plurality of amplifiers42, to the amplifier42of the ignition unit40having the ignition coil35, which receives the high-voltage-output signal, and outputs a control signal to the amplifier42thus set, thereby switching the amplifier42. As a result thereof, the amplifier42amplifies the electromagnetic wave outputted from the oscillator41, and outputs the amplified electromagnetic wave to the mixer38. The mixer38is inputted with the high voltage pulse from the ignition coil35and the electromagnetic wave from the amplifier42, and supplies the high voltage pulse and the electromagnetic wave to the central electrode15aof the ignition plug15.

As a result thereof, a spark discharge occurs due to the high voltage pulse at a discharge gap between the central electrode15aand a ground electrode15bof the ignition plug15, and small scale plasma is generated. The small scale plasma is irradiated with an electromagnetic wave from the central electrode15aof the ignition plug15. The small scale plasma absorbs the energy of the electromagnetic wave and expands. In the combustion chamber10, the expanded plasma causes volume ignition of the air fuel mixture, and combustion of the air fuel mixture starts. The electromagnetic wave is radiated from before and until after the spark discharge.

After the combustion of the air fuel mixture starts, the piston23is moved toward the bottom dead center by the expansion force of the combustion of the air fuel mixture. Before the piston23reaches the bottom dead center, the exhaust valve28is opened, and the exhaust stroke starts. As described above, the exhaust stroke ends immediately after the intake stroke starts.

In the present embodiment, the amplifier42of the ignition unit40attached to the cylinder24, in which the piston23is immediately before reaching the top dead center in the compression stroke, is selected as the amplifier42, which amplifies the electromagnetic wave. Subsequently, the electromagnetic wave amplified by the selected amplifier42is radiated to the combustion chamber10from the central electrode15aof the ignition plug15of the ignition unit40to which the selected amplifier42belongs.

According to the present embodiment, in the electromagnetic wave oscillation device37, a part to be integrated with the ignition plug15is limited to the amplifier42, thereby shortening the transmission line between the amplifier42and the ignition plug15, where electric power loss is relatively high. Since a part to be integrated with the ignition plug15is limited to the amplifier42, it is possible to avoid the ignition unit40from increasing in size. Accordingly, even if an installation space for the ignition unit40is small, it is possible to reduce electric power loss in the transmission line between the electromagnetic wave oscillation device37and the ignition plug15.

Furthermore, according to the present embodiment, since the semiconductor element that is small in comparison to a magnetron is employed as the electromagnetic wave oscillation device37, it is possible to downsize the plasma generation device30.

Furthermore, according to the present embodiment, the high frequency switch60is provided, thereby enabling to selectively emit the microwave from the plurality of ignition plugs15, even if the oscillators41are fewer in number than the ignition plugs15. Accordingly, it is possible to simplify the electromagnetic wave oscillation device37compared to a case in which as many oscillators41are provided as the ignition plugs15.

Furthermore, according to the present embodiment, since the oscillator41is accommodated in the same casing39as the power circuit for electromagnetic wave36, it is possible to simplify a construction that accommodates the oscillator41and the power circuit for electromagnetic wave36.

Furthermore, according to the present embodiment, since the amplifier42dissipates heat to the outside utilizing the metal casing45that accommodate the amplifier42itself, it is possible to simplify heat dissipation parts of the amplifier42.

Other Embodiments

The above described embodiment may also be configured as follows.

In the embodiment described above, the amplifier42may include a plurality of stages of amplifying elements43aand43b. For example, the amplifier42includes a primary amplifying element43athat amplifies the electromagnetic wave inputted from the oscillator41, and a secondary amplifying element43bthat amplifies the electromagnetic wave outputted from the primary amplifying element43a. In this case, as shown inFIG. 4, for each primary amplifying element43a, a plurality of the secondary amplifying elements43bare installed in parallel connection, and the electromagnetic wave amplified by the respective secondary amplifying elements43bare combined by a power combiner34. The amplifier42may be entirely integrated with the ignition plug15. Only the secondary amplifying element43bof downstream stage may be integrated with the ignition plug15. In the latter case, the high frequency switch60shown inFIG. 5switches the supply destination of the electromagnetic wave outputted from the primary amplifying element43afrom among the plurality of secondary amplifying elements43b. In a case in which the amplifier42includes more than two stages of amplifying elements43, downstream stages of amplifying elements43to be integrated with the ignition plug15may be more than one in number.

Furthermore, in the embodiment described above, the amplifying element43may dissipate heat in cooling water for cooling the internal combustion engine20. For example, a metal plate extending from a flowing path of the cooling water of the internal combustion engine20may abut the metal casing45.

Furthermore, in the embodiment described above, application of the high voltage pulse and radiation of the electromagnetic wave may take place at different locations. In this case, an antenna is provided apart from the central electrode15ain the ignition plug15. The mixer38is not necessary. The ignition coil35is directly connected to the central electrode15aof the ignition plug15, and the amplifier42is directly connected to the antenna. The antenna is integrated with the ignition plug15in such a manner as to penetrate through an insulator of the ignition plug15. Also, the antenna may be attached to the cylinder head22separately from the ignition plug15.

INDUSTRIAL APPLICABILITY

The present invention is useful in relation to a plasma generation device that generates plasma by supplying a high frequency wave to a target space.

EXPLANATION OF REFERENCE NUMERALS