Electron beam emission device

Disclosed is an electron beam emission device comprising a housing which defines a space in which electron beams are accelerated, and has an opening at the other side thereof through which the electron beams are emitted; a cathode which is disposed at one side in the housing, and emits the electrons; an anode which is positioned in the housing so as to be spaced apart from the cathode toward the other side, and accelerates the electrons emitted from the cathode; and an insulation holder which insulates a portion between the cathode and the housing, and fixes the cathode, wherein the cathode has a surface which faces the anode and is formed concavely to have a gradient, and a rim of the surface of the cathode, which has the gradient, is formed to be rounded.

CROSS REFERENCE TO PRIOR APPLICATIONS

This application is a National Stage Application of PCT International Patent Application No. PCT KR2014/012577 filed on Dec. 19, 2014, under 35 U.S.C. § 317, which claims priority to Korean Patent Application Nos. 10-2014-0119183 filed on Sep. 5, 2014 and 10-2014-0119186 filed on Sep. 5, 2014, which are all hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present application relates to an electron beam emission device provided with a reflection electron blocking structure, and more particularly, to an electron beam emission device provided with a reflection electron blocking structure which is capable of operating more stably and producing a high output.

BACKGROUND ART

An electron beam emission device refers to a device for performing various processing, such as melting or reforming of a surface of a processed product, by emitting electrons by using high energy, and recently, the electron beam emission device is applied to various processing device fields in addition to an image display means or a non-destructive inspection device.

In general, as the electron beam emission device, a thermal type electron beam emission device, which emits electron beams by applying high voltage and high current to a filament, is used, but there are difficulties in maintaining a high degree of vacuum and manufacturing the filament, which directly causes problems with maintenance of the device.

Meanwhile, a cold type electron beam emission device, which is contrasted with the thermal type electron beam emission device, has been introduced. Various types of the cold type electron beam emission device have also been introduced.

FIG. 1is a view illustrating an electron beam emission device using a concave cathode among the cold type electron beam emission devices.

As illustrated inFIG. 1, an electron beam emission device in the related art may include a cathode20, an anode30, an insulation unit40, and a tube50.

The cathode20is disposed at one end of the tube50, and a downward surface of the cathode20has a gradient so as to be concave.

Further, the anode30is disposed at the other end in the tube50, and disposed to be spaced apart from the cathode20.

The cathode20is fixed to the tube50by the insulation unit40, and a drive unit60for controlling electrical energy applied to the cathode20and a cooling unit70for cooling the cathode20are provided outside the insulation unit40.

Meanwhile, the tube50is made of a quartz material which enables an internal state to be observed, withstands a high temperature, and enables insulation.

In addition, a focusing unit80and a deflecting unit90are installed at a lower side of the anode30, thereby focusing and deflecting the emitted electron beams.

Therefore, the electrons emitted from the cathode20may form the electron beams while being accelerated and emitted by the anode30, and may be focused while passing through the focusing unit80, and an emission direction of the electrons may be deflected while the electrons pass through the deflecting unit90.

However, the aforementioned electron beam emission device in the related art has the following problems.

First, because a rim22of the cathode20is formed in the form of a pointed end as illustrated inFIG. 2, an arc is generated at the rim22of the cathode20when high energy is applied such that the electron beam emission device10operates unstably, and as a result, there is a limitation in increasing an output.

Second, since a tube made of a quartz material is used as the tube50, there is a problem in that the tube50is easily damaged due to impact applied when the device operates and repeated thermal shock.

Third, in a case in which metal is processed as a processing object to be processed by the electron beam emission device10, metal vapor (fume) vaporized by the electron beams may be adhered and deposited on the tube, and the deposited metal vapor generates an arc when the electron beam emission device operates, and thus acts as a factor that limits use duration time of the tube.

Fourth, radioactive rays such as X-rays, which are harmful to a human body, may be generated when the electrons are reflected by the anode30, but the tube made of a quartz material cannot block the radioactive rays, and as a result, there is a problem in that an environment harmful to an operator may be made.

Fifth, some of the electron beams emitted from the cathode20are not directed toward the anode, and may form backscattered electrons (BSE) that are directed in other directions.

Further, secondary electrons9may be emitted as elements such as nitrogen in the tube50collide with the accelerated electrons, and the secondary electrons9are scattered without being focused in comparison with the electron beams emitted from the cathode20, and may be reflected in the tube50without passing through the anode30.

In the following description, both of the backscattered electron and the secondary electron are referred to as a reflection electron.

Even though the reflection electron9does not have high energy, the reflection electron9may become a factor that serves to increase a temperature in the tube50by being reflected in the tube50, or hinders a stable operation while generating an arc.

DISCLOSURE

Technical Problem

The present application has been made in an effort to solve the problems, and an object of the present application is to provide an electron beam emission device capable of more stably operating over a long period of time and producing a high output.

In addition, another object of the present application is to provide an electron beam emission device capable of more stably operating over a long period of time by inhibiting reflection electrons from being reflected back into the tube.

Technical Solution

To achieve the objects, an aspect of the present application provides an electron beam emission device including: a housing which defines a space in which electron beams are accelerated, and has an opening at the other side thereof through which the electron beams are emitted; a cathode which is disposed at one side in the housing, and emits the electrons; an anode which is positioned in the housing so as to be spaced apart from the cathode toward the other side, and accelerates the electrons emitted from the cathode; and an insulation holder which insulates a portion between the cathode and the housing, and fixes the cathode, in which the cathode has a surface which faces the anode and is formed concavely to have a gradient, and a rim of the surface of the cathode, which has the gradient, is formed to be rounded.

The insulation holder may be formed to surround a rear surface of the surface of the cathode which has the gradient, surround a lateral surface of the cathode, and extend to the rounded portion of the rim of the cathode.

A surface of the cathode, which faces the anode, may be disposed to be closer to the anode than the insulation holder.

A tube, which is made of a metallic material and defines a lateral surface of the housing, may be provided.

The tube may be insulated from the cathode, and grounded.

A cooling unit, which cools the cathode in an air-cooled manner, may be further provided between the cathode and the insulation holder.

The cooling unit may include an upper plate and a lower plate, and a flow path through which air flows may be formed between the upper plate and the lower plate.

The electron beam emission device may further include a reflection electron blocking structure which is disposed in the housing, is formed to extend toward the anode from the periphery of an emission port of the housing, and blocks secondary electrons and backscattered electrons, which are reflected at the periphery of the emission port of the housing, from being reflected into the housing.

The reflection electron blocking structure may be disposed between the anode and a surface of the housing in which the emission port is formed, may extend toward the anode from the surface in which the emission port is formed, may have an internal hollow portion, and may be formed in the form of a tube that is opened at a side directed toward the anode and at a side directed toward the emission port.

The internal hollow portion of the reflection electron blocking structure may communicate with the emission port, and may have a diameter larger than a diameter of the emission port.

A flange portion, which extends inward from an inner circumferential surface of the reflection electron blocking structure, may be further formed.

A diameter of an opening formed by an inner circumferential surface of the flange portion may have a magnitude that allows metal vapor flowing upward through the emission port to be guided to the cathode.

A plurality of absorbing grooves, which absorbs the backscattered electrons and the secondary electrons, may be formed in an inner circumferential surface of the reflection electron blocking structure.

A cooling pipe through which a cooling medium flows may be provided on an outer circumferential surface of the reflection electron blocking structure.

A blocking plate, which blocks the electrons from being emitted directly to the cooling pipe, may be further provided outside the cooling pipe.

Meanwhile, another aspect of the present application provides an electron beam emission device including: a housing which defines a space in which electron beams are accelerated, and has an emission port at the other side thereof through which the accelerated electron beams are emitted; a cathode which is disposed at one side in the housing, and emits the electrons; an anode which is positioned in the housing so as to be spaced apart from the cathode toward the other side, and accelerates the electrons emitted from the cathode; and a reflection electron blocking structure which is disposed in the housing, is formed to extend toward the anode from the periphery of the emission port of the housing, and blocks secondary electrons and backscattered electrons, which are reflected at the periphery of the emission port of the housing, from being reflected into the housing.

The reflection electron blocking structure may be disposed between the anode and a surface of the housing in which the emission port is formed, may extend toward the anode from the surface in which the emission port is formed, may have an internal hollow portion, and may be formed in the form of a tube that is opened at a side directed toward the anode and at a side directed toward the emission port.

The internal hollow portion of the reflection electron blocking structure may communicate with the emission port, and may have a diameter larger than a diameter of the emission port, and a flange portion, which extends inward from an inner circumferential surface of the reflection electron blocking structure, may be further formed.

A plurality of absorbing grooves, which absorbs the backscattered electrons and the secondary electrons, may be formed in an inner circumferential surface of the reflection electron blocking structure.

Advantageous Effects

The electron beam emission device of the present application has the following effects.

First, since the rim of the cathode is not formed in the form of a pointed end, the occurrence of an arc is inhibited, and as a result, it is possible to more stably operate the electron beam emission device, and to further increase a critical output.

Second, since a space in which charges are stored is reduced as an interval between the cathode and the insulation holder is reduced, such that a capacitance between the cathode and the insulation holder is reduced, the occurrence of an arc is inhibited, and as a result, it is possible to more stably operate the electron beam emission device, and to further increase a critical output.

Third, since the tube is made of a metallic material, there is no concern that the tube is damaged due to thermal shock such as thermal expansion and thermal contraction, and impact applied from the outside, and since the tube is grounded, the occurrence of an arc caused by fume is inhibited, and as a result, it is possible to increase a critical output, and increase a lifespan of the device.

Fourth, since the tube is made of a metallic material, X-rays, which are generated when the electrons are reflected at the anode, may be blocked, and as a result, it is possible to improve safety for an operator.

Fifth, it is possible to maximally inhibit an increase in temperature in the housing by blocking the backscattered electrons and the secondary electrons from being reflected back in the housing, and it is also possible to prevent an arc from being generated due to the reflected electrons, and as a result, the electron beam emission device may more stably operate over a long period of time and may produce a high output.

The effects of the present invention are not limited to the aforementioned effects, and other effects, which are not mentioned above, will be clearly understood by those skilled in the art from the claims.

BEST MODE

Hereinafter, an exemplary embodiment of the present invention for specifically accomplishing the objects of the present invention will be described with reference to the accompanying drawings. In the description of the present exemplary embodiment, like terms and like reference numerals are used for like configurations, and additional descriptions will be omitted.

As illustrated inFIG. 3, an electron beam emission device100according to the present exemplary embodiment may include a housing150, a cathode120, an anode130, and an insulation holder140.

The housing150is a constituent element which defines a space in which the cathode120and the anode130, which will be described below, are positioned and electron beams are accelerated, and an emission port156, through which the accelerated electron beams are emitted, may be formed at the other side of the housing150, and an interior of the housing150may be in a vacuum atmosphere.

Further, the cathode120is provided at one side in the housing150. The cathode120is a constituent element which emits the electrons by receiving electrical energy, and in the present exemplary embodiment, an example in which the cathode120is made of a metallic material and has an entirely circular plate shape having a predetermined thickness will be described.

In the housing150, the anode130may be positioned to be spaced apart from the cathode120toward the other side. The anode130is a constituent element which accelerates the electrons emitted from the cathode120by receiving electrical energy, and may have an opening132through which the accelerated electrons pass.

Meanwhile, the insulation holder140is a constituent element which insulates a portion between the cathode120and the housing150, and fixes the cathode120to the housing150.

In addition, a drive unit160, which supplies electrical energy to the cathode120or the anode130, and a cooling unit170, which cools the cathode120, may be provided at one side of the insulation holder140.

Further, although not illustrated in the drawings, a focusing unit (not illustrated) or a deflecting unit (not illustrated), which focuses or deflects the electron beam passing through the opening132of the anode130, may be provided at the other side of the anode130.

Therefore, when electrical energy is applied to the cathode120and the anode130, the electrons may be emitted from the cathode120, accelerated toward the anode130, and then emitted through the emission port156of the housing150.

Meanwhile, as illustrated inFIGS. 3 and 4, a surface of the cathode120, which faces the anode130, may be formed concavely to have a gradient.

Further, a rim122of the surface of the cathode120, which has the gradient, may be formed to be rounded.

Therefore, a pointed end portion is not formed at the rim of the cathode120, and as a result, the occurrence of an arc is prevented, and a more stable operation is enabled.

Further, the insulation holder140is formed to surround a rear surface of the surface of the cathode120which has the gradient, and surround a lateral surface of the cathode120, and a portion of the insulation holder140, which surrounds the lateral surface of the cathode120, may be formed to extend to the rounded portion122of the rim of the cathode.

In addition, as illustrated inFIG. 5, since the insulation holder140extends to the lateral surface of the cathode120, the occurrence of an arc may be prevented between the housing150and the cathode120.

In this case, the insulation holder140may be formed to extend so as to surround a part of the rounded portion of the rim122of the cathode.

That is, the cathode120may be positioned to be closer to the anode130than the insulation holder140.

As described above, since the rim of the cathode120is formed to be rounded, a space C may be formed between the insulation holder140and the cathode120, and in this case, the space C serves as a space in which charges are accumulated, and as a result, an arc may be generated when the electron beam emission device operates.

Therefore, since the cathode120is positioned to be closer to the anode130than the insulation holder140, an interval between the cathode120and the insulation holder140is decreased, and the space C in which charges are accumulated may be reduced.

Therefore, a capacitance between the cathode120and the insulation holder140is reduced, such that the occurrence of an arc is inhibited, and as a result, it is possible to more stably operate the electron beam emission device, and to further increase a critical output.

Meanwhile, the housing150may include a tube152which defines a circumference of a lateral surface of the housing150.

In this case, the tube152may be made of a metallic material, and may be insulated from the cathode120. To this end, an insulator154may be provided between the tube152and the cathode120.

In a case in which metal is processed by the electron beam emission device, metal vapor is generated from molten metal, and the generated metal vapor may be deposited on an inner surface of the tube152.

In this case, since the tube152is grounded158, the electrons at the periphery of the metal vapor attached to the inner surface of the tube152flow to the ground where the tube is grounded158, such that the occurrence of an arc is prevented, and as a result, it is possible to more stably operate the electron beam emission device, and to increase a critical output.

In addition, because of the nature of the metallic material, the electron beam emission device is strong against external impact and repeated thermal shock, and may be operated even though the attached metal vapor is not removed, and as a result, the electron beam emission device may be used semipermanently.

In addition, radioactive rays such as X-rays, which are harmful to a human being, may be generated when the electrons are reflected by the anode or the like, but since the tube is made of a metallic material, and as a result, it is possible to block the radioactive rays and thus to improve safety for the operator.

In addition, as illustrated inFIG. 3, the cooling unit170includes an upper plate172and a lower plate174, and a flow path176, through which air flows, may be formed in the cooling unit170. In addition, the flow path176is connected to an external cooling air supply device (not illustrated) such that outside air is circulated, and as a result, the cathode120may be cooled in an air-cooled manner.

In a case in which the cathode120is cooled in a water-cooled manner using a coolant, an electric current leak phenomenon in which the electric current to be applied to the cathode120flows to the coolant may occur, in spite of the insulation, when high voltage is applied to the cathode120, but in the present application, since the cathode120is cooled in an air-cooled manner, it is possible to avoid the electric current leak phenomenon.

Further, a reflection electron blocking structure200may be provided.

As illustrated inFIGS. 6 and 7, some electron beams at the outer periphery among electron beams5emitted from the cathode120cannot be directed toward the anode130, but may form backscattered electrons (BSE)7that move in other directions.

In addition, secondary electrons9may be generated as elements such as nitrogen, which remain in the tube152, collide with the accelerated electrons.

In the following description, both of the backscattered electron and the secondary electron are referred to as a reflection electron.

The reflection electrons7and9are not focused in comparison with the electron beams5passing through the anode130and thus do not have directionality, or may be scattered.

The reflection electrons7and9may heat the tube152or generate an arc by being reflected in the housing150, and since the tube152of the electron beam emission device100of the present exemplary embodiment is made of a metallic material such as stainless steel, a geometric condition is changed when the tube152is heated and thermally expanded, and as a result, there may be a problem in that precision of the electron beam emission device100deteriorates.

Therefore, the reflection electron blocking structure200is a constituent element which blocks the reflection electrons7and9from moving toward the interior of the tube152.

As illustrated inFIGS. 6 and 7, the reflection electron blocking structure200may be formed to extend toward the anode130from the periphery of the emission port156at a surface of the housing150in which the emission port156is formed.

Therefore, the reflection electron blocking structure200is disposed between the anode130and the surface in which the emission port156is formed, and may be formed in the form of a tube extending toward the anode130from the surface in which the emission port156is formed.

In this case, the reflection electron blocking structure200is opened at a side directed toward the anode130and at a side directed toward the emission port156, and a hollow portion may communicate with the anode130and the emission port156.

Therefore, the hollow portion of the reflection electron blocking structure200may serve as a passageway through which the electrons accelerated through the opening132of the anode130are emitted to the emission port156.

In this case, the hollow portion may be formed coaxially with the emission port156so as to have a diameter larger than a diameter of the emission port156, and may have a diameter equal to or smaller than a diameter of the opening132of the anode130.

Further, the emission port156may be formed to have a diameter smaller than a diameter of the opening132of the anode130.

In addition, a flange portion210may be formed to extend inward from an inner circumferential surface of the reflection electron blocking structure200. The flange portion210may be formed on an upper portion of the reflection electron blocking structure200, and a length to which the flange portion210protrudes may be set to such an extent as not to hinder the accelerated electrons passing through the opening132of the anode130from passing through the reflection electron blocking structure200.

In addition, metal vapor may be generated from molten metal when metal is processed by the electron beam emission device, and the metal vapor may flow into the housing150through the emission port156and may be deposited on the tube152or the insulation holder140, thereby generating an arc. However, in a case in which the metal vapor is deposited on the surface of the cathode120which is formed concavely to have a gradient, the metal vapor may be vaporized by high energy of the electron beam without being deposited.

Therefore, a diameter of the flange portion210may be set to a diameter that allows the metal vapor flowing in through the emission port156not to be dispersed in the housing, but to be guided toward the surface of the cathode120which is formed concavely to have a gradient.

The accelerated electrons passing through the opening132of the anode130may be emitted to the emission port156of the housing150through the hollow portion of the reflection electron blocking structure200.

Meanwhile, the reflection electrons7and9cannot pass through the emission port156of the housing150, but may be reflected by the surface of the housing150in which the emission port156is formed.

In this case, the reflected electrons are reflected in the inner circumferential surface of the reflection electron blocking structure200, and as a result, it is possible to prevent the reflected electrons from being reflected back to the tube152.

Since the flange portion210extends inward from the inner circumferential surface, it is possible to prevent the electrons, which are reflected in the hollow portion of the reflection electron blocking structure200, from escaping from the reflection electron blocking structure200to the outside from escaping to the outside of the reflection electron blocking structure200, and the metal vapor flowing in through the emission port156is not dispersed in the housing, but is guided to be directed toward the surface of the cathode120which is formed concavely to have a gradient, and as a result, it is possible to prevent the metal vapor from being deposited on the tube152or the insulation holder140.

In addition, a plurality of absorbing grooves220is formed in the inner circumferential surface of the reflection electron blocking structure200, and the probability of a collision between the reflection electrons and the plurality of grooves is increased, and as a result, it is possible to absorb the electrons reflected in the hollow inner circumferential surface of the reflection electron blocking structure200.

Meanwhile, the reflection electron blocking structure200may be heated by the reflection electrons7and9, and a cooling pipe230, through which a cooling medium flows, may be provided around an outer circumferential surface of the reflection electron blocking structure200in order to prevent the reflection electron blocking structure200from overheating.

The cooling medium may be water or other fluids that are advantageous in cooling the reflection electron blocking structure200.

Therefore, the reflection electron blocking structure200may be cooled, and since the cooling pipe230is provided around the outer circumferential surface of the reflection electron blocking structure200, even though the cooling medium leaks from the cooling pipe230, the leaking cooling medium leaks between the tube152and the reflection electron blocking structure200, and as a result, it is possible to prevent the cooling medium from leaking to the outside of the electron beam emission device through the anode130and the emission port156.

Further, a blocking plate240is further provided outside the cooling pipe230, and as a result, it is possible to block the reflection electrons7and9from being emitted directly to the cooling pipe230, thereby preventing damage to the cooling pipe230.

While the exemplary embodiments according to the present invention have been described above, it is obvious to those skilled in the art that the present invention may be specified in other particular forms in addition to the aforementioned exemplary embodiments without departing from the spirit or the scope of the present invention. Accordingly, it should be understood that the aforementioned exemplary embodiments are not restrictive but illustrative, and thus the present invention is not limited to the aforementioned description, and may be modified within the scope of the appended claims and the equivalent range thereto.