A high-power gas discharge electron gun

Abstract

The present invention discloses a high-power gas discharge electron gun, belonging to the technical field of electron guns. It includes a water-cooled discharge chamber outer shell, as well as a cathode and an anode placed in the water-cooled discharge chamber outer shell. The water-cooled discharge chamber outer shell, the cathode, and the anode form a discharge chamber. At one end of the anode far from the cathode, a porous gas flow guiding component is installed, which optimizes the traditional single gas flow input mode into a porous gas flow input mode, ensuring that the gas flow input into the discharge chamber is evenly distributed along the inner wall of the discharge chamber in a laminar flow state, reducing the occurrence probability of low-voltage and high-current arc discharge; an arc discharge infrared detection unit is arranged near the discharge chamber, which can quickly detect the occurrence and disappearance moments of low-voltage and high-current arc discharge in the discharge chamber, providing precise control parameters for the control circuit and adjusting the working state of the power supply of the gas discharge electron gun, thereby ensuring the long-term stable operation of the gas discharge electron gun.

Description

Technical Field

[0001] The present invention belongs to the technical field of electron guns, and particularly relates to a high-power gas discharge electron gun. Background Art

[0002] The electron beam processing technology has been widely applied in industries such as aerospace, shipbuilding, automotive, chemical, and medical fields, achieving remarkable social and economic benefits. The core device of the electron beam processing technology is the electron gun, and the electron gun can be divided into a hot cathode electron gun and a cold cathode electron gun according to the way of electron generation.

[0003] The hot cathode electron gun usually has a relatively high working voltage. The highest working voltage of the hot cathode electron gun commonly used in the industrial field can reach up to -150 kV. However, it is difficult to implement a high-voltage high-power hot cathode electron gun with a power of hundreds of kilowatts. Moreover, the working life of the cathode of the hot cathode electron gun is limited, generally only dozens of hours, and it is difficult to adapt to the working environment that requires long-term stable operation and high-power beam current output.

[0004] The cold cathode electron gun can be strictly divided into a cold cathode gas discharge electron gun based on a plasma cathode and a cold cathode gas discharge electron gun based on a plasma anode according to the characteristics of the emitted electrons. The cold cathode gas discharge electron gun based on a plasma cathode specifically refers to an electron gun structure that uses the plasma generated by the discharge gas as one electrode and extracts electrons from it. Since it is difficult to extract electrons from the plasma generated by the discharge gas, it is generally difficult to increase the power, and it is usually not applicable to the working environment with an electron beam power output of dozens of kilowatts or even hundreds of kilowatts. The working principle of the cold cathode gas discharge electron gun based on a plasma anode is that in a pressure environment of a few tenths of a pascal or dozens of pascals, the discharge chamber is filled with working gas, and a voltage of several thousand to several tens of kilovolts is applied between the cathode and the anode to cause gas discharge between the cathode and the anode to form plasma. The positive ions in the plasma bombard the surface of the cathode under the action of the electric field to generate secondary electrons. The secondary electrons and the electrons in the plasma are accelerated by the acceleration voltage between the cathode and the anode, and with the focusing function of the electrostatic focusing system and the electromagnetic focusing system of such an electron gun, an electron beam with highly concentrated energy is formed. The cold cathode gas discharge electron gun based on a plasma anode is also called a gas discharge electron gun, and its power can generally reach hundreds of kilowatts and has been applied both at home and abroad.

[0005] The gas discharge electron gun has a high power and requires a uniform input of working gas to ensure a stable output of the electron beam. Moreover, there is inevitably a low-voltage and high-current arc discharge phenomenon inside the discharge chamber, and it is necessary to quickly detect this phenomenon and provide protection to maintain the stable output of the electron beam. However, the working gas of the gas discharge electron gun is generally input into the discharge chamber of the gas discharge electron gun through a single air inlet. In the low-pressure environment inside the discharge chamber, it is difficult for the working gas to achieve a uniform laminar flow distribution along the entire inner wall of the discharge chamber, and it is extremely easy to form a phenomenon where the gas flow distribution is more at a certain position and less at other positions. This will not only cause uneven energy distribution of the electron beam spot, but also easily cause low-voltage and high-current arc discharge at the position with more gas flow distribution, making it difficult to stabilize the output process of the electron beam of the gas discharge electron gun.

[0006] Currently, for the low-voltage and high-current arc discharge phenomenon that occurs in the gas discharge electron gun, the commonly used method is generally to use a discharge arc extinguishing circuit. When the system detects the low-voltage and high-current arc discharge state of the gas discharge electron gun, the high-voltage output of the driving power supply of the electron gun is turned off for several milliseconds to dozens of milliseconds. After the high-current arc discharge state disappears, the high-voltage output is restored to the normal state. This type of detection method cannot quickly judge the occurrence and disappearance moments of the arc discharge in the discharge chamber. The time for the driving power supply to turn off the high-voltage output needs to be adjusted repeatedly, and it is very cumbersome to adjust the parameters of the discharge arc extinguishing circuit to obtain a stable output of the electron beam. Moreover, when changing the type of the working gas for the electron gun discharge, or adjusting the working voltage and the input gas flow rate, it is necessary to re-adjust the parameters of the discharge arc extinguishing circuit to ensure a stable output of the electron beam. Otherwise, it is very easy to cause a large range of fluctuations in the electron beam, affecting the processing quality and possibly generating electromagnetic interference to affect the normal operation of other nearby devices. Summary of the Invention

[0007] Object of the Invention: Aiming at the problems existing in the prior art, the present invention discloses a high-power gas discharge electron gun, which can achieve a uniform laminar flow distribution of the working gas along the entire inner wall of the discharge chamber, and can quickly detect the occurrence and disappearance moments of the low-voltage and high-current arc discharge and provide protection, ultimately achieving the purpose of maintaining a stable output of the electron beam.

[0008] Technical Solution: To achieve the above object of the invention, the present invention adopts the following technical solution:

[0009] A high-power gas discharge electron gun includes a water-cooled discharge chamber outer shell and a cathode and an anode disposed in the water-cooled discharge chamber outer shell. One end of the cathode facing the anode is an inwardly concave spherical structure, the anode is a funnel-shaped structure, the outer edge width of one end of the anode facing the cathode is greater than the outer edge width of the end of the anode away from the cathode, and an arc starting boss is provided on the inner wall of the water-cooled discharge chamber outer shell, and the inner edge of the arc starting boss is parallel to the outer edge of the end of the cathode facing the anode;

[0010] One end of the cathode is installed with an insulator inside the outer shell of the water-cooled discharge cavity. The cathode is installed on one end of the insulator facing the anode. The insulator is hermetically connected to the cathode through a sealing component. One end of the insulator away from the anode is provided with a top flange, and the top flange of the insulator is hermetically connected to the outer shell of the water-cooled discharge cavity;

[0011] The top flange of the insulator located inside the outer shell of the water-cooled discharge cavity is provided with an internal infrared receiving diode group facing the inner side of the outer shell of the water-cooled discharge cavity. The internal infrared receiving diode group includes a number of infrared detection diodes, and the detection signals of the infrared detection diodes are introduced into an external detection circuit;

[0012] One end of the anode away from the cathode is installed on a porous gas flow guiding component. The porous gas flow guiding component is hermetically connected to one end of the outer shell of the water-cooled discharge cavity close to the anode. The porous gas flow guiding component is sequentially provided with a concave stop port and a central through hole along the direction away from the cathode. One end of the anode away from the cathode is installed in the concave stop port of the porous gas flow guiding component. There is a gap between the inner side wall of the concave stop port of the porous gas flow guiding component and the anode. The anode is also provided with a central through hole, and the central through hole of the anode is on the same axis as the concave stop port and the central through hole of the porous gas flow guiding component; An air flow input port is arranged on the outer side wall of the porous gas flow guiding component, and a number of air flow output ports are arranged on the inner side wall of the concave stop port of the porous gas flow guiding component. The air flow input port and the air flow output port are connected through an internal pipeline of the porous gas flow guiding component.

[0013] Preferably: The external detection circuit includes a number of comparator circuits. The number of comparator circuits is the same as the number of infrared detection diodes and the comparator circuits correspond to the infrared detection diodes one by one. The structures of the comparator circuits are the same. Each comparator circuit includes 1 comparator. The positive input terminal of the comparator is connected to the VCC positive voltage through 1 resistor and grounded through 1 resistor. The negative input terminal of the comparator is connected to the positive electrode of the corresponding infrared detection diode. The negative input terminal of the comparator is connected to the VCC positive voltage through 1 resistor, and the negative electrode of the corresponding infrared detection diode is grounded. The output terminal of the comparator is the output terminal of the corresponding comparator circuit. The output terminal of this comparator is connected to the VCC positive voltage through 1 resistor. The output terminal of the comparator is connected to the first output terminal of the external detection circuit through a diode, where the output terminal of the comparator is connected to the positive electrode of this diode. The first output terminal of the external detection circuit is grounded through 1 resistor. The output terminal of the comparator is also connected to the second output terminal of the external detection circuit through a diode, where the output terminal of the comparator is connected to the negative electrode of this diode. The second output terminal of the external detection circuit is connected to the VCC positive voltage through 1 resistor.

[0014] Preferably: The gap between the outer edge of one end of the anode facing the cathode and the inner wall of the outer shell of the water-cooled discharge cavity is less than 1 mm;

[0015] The distance between the inner edge of the arc starting boss and the outer edge of the end of the cathode facing the anode is not less than 10 mm.

[0016] Preferably, the outer shell of the water-cooled discharge cavity is a hollow structure, provided with a water inlet and a water outlet for the outer shell of the water-cooled discharge cavity;

[0017] The cathode is a hollow structure, provided with a cathode water inlet and a cathode water outlet.

[0018] Preferably, the internal pipeline of the porous gas flow guiding assembly includes a first gas flow buffer pipeline and a second gas flow buffer pipeline. The first gas flow buffer pipeline is connected to the gas flow input port, the second gas flow buffer pipeline is connected to the gas flow output port, an air flow blocking wall is arranged between the first gas flow buffer pipeline and the second gas flow buffer pipeline, and air flow connection through holes are arranged on the air flow blocking wall.

[0019] Preferably, a plurality of bosses are arranged on the surface from the top convex edge of the insulator to the cathode mounting end face and facing the inner wall of the outer shell of the water-cooled discharge cavity.

[0020] Preferably, a water-cooled beam guiding channel is installed at one end of the porous gas flow guiding assembly away from the anode. The water-cooled beam guiding channel is coaxially and hermetically connected and fixed with the porous gas flow guiding assembly. A through hole is arranged in the center of the water-cooled beam guiding channel, and the diameter of the through hole is not less than the diameter of the central through hole of the anode;

[0021] The water-cooled beam guiding channel is sequentially provided with a pre-focusing coil, a coaxial coil, a main focusing coil and a scanning coil, where:

[0022] A pre-focusing coil is installed at one end of the water-cooled beam guiding channel close to the porous gas flow guiding assembly;

[0023] A coaxial coil is installed at one end of the pre-focusing coil away from the porous gas flow guiding assembly;

[0024] A main focusing coil is installed at one end of the coaxial coil away from the pre-focusing coil;

[0025] A scanning coil is installed at one end of the main focusing coil away from the coaxial coil.

[0026] Preferably, a coil water cooling unit is arranged between the coaxial coil and the main focusing coil; the coil water cooling unit is provided with a coil water cooling unit water inlet and a coil water cooling unit water outlet.

[0027] Preferably, the water-cooled beam guiding channel is a hollow structure, provided with a water-cooled beam guiding channel water inlet and a water-cooled beam guiding channel water outlet.

[0028] Preferably, an installation flange is provided at one end of the water-cooled beam guiding channel away from the porous gas guiding assembly.

[0029] Advantages: Compared with the prior art, the present invention has the following remarkable advantages:

[0030] 1. The present invention is provided with a porous gas guiding assembly, which optimizes the traditional single gas input mode into a porous gas input mode, and can ensure that the gas input into the discharge chamber is evenly distributed along the inner wall of the discharge chamber in a laminar flow state, reducing the occurrence probability of low-pressure high-current arc discharge;

[0031] 2. The present invention installs an arc discharge infrared detection unit based on an infrared detection diode on the gas discharge electron gun, which can quickly detect the occurrence and disappearance moments of low-pressure high-current arc discharge in the discharge chamber, provide precise control parameters for the control circuit, and adjust the working state of the power supply of the gas discharge electron gun, thereby ensuring the long-term stable operation of the gas discharge electron gun;

[0032] 3. The present invention is provided with an electron optical system of the gas discharge electron gun composed of a pre-focusing coil, a coaxial coil, a main focusing coil, and a scanning coil, which can more conveniently adjust the morphology of the electron beam spot and the energy distribution state of the electron beam on the workpiece surface, meeting the requirements of more complex electron beam processing technologies. Description of the Drawings

[0033] Figure 1 is a schematic diagram of a high-power gas discharge electron gun according to the present invention;

[0034] Figure 2 is a cross-sectional view of the porous gas guiding assembly of the present invention;

[0035] Figure 3 is a schematic diagram of the layout of the internal gas connection through holes and gas output ports of the porous gas guiding assembly of the present invention;

[0036] Figure 4 is a block diagram of the external detection circuit of the arc discharge infrared detection unit of the present invention;

[0037] Figure 5 is a schematic diagram of the layout of the built-in infrared receiving diode group of the arc discharge infrared detection unit of the present invention;

[0038] In the figure: 1. Cathode; 101. Cathode sealing assembly; 102. Cathode water inlet; 103. Cathode water outlet; 2. Anode; 3. Insulator; 4. Arc starting boss; 5. Built-in infrared receiving diode group; 501. First infrared detection diode; 502. Second infrared detection diode; 503. Third infrared detection diode; 504. Fourth infrared detection diode; 6. External detection circuit; 7. High-voltage wire; 8. Porous gas flow guiding assembly; 801. Gas flow input port; 802. First gas flow buffer pipe; 803. Second gas flow buffer pipe; 804. Gas flow shielding wall; 9. Water-cooled discharge chamber outer shell; 901. Water-cooled discharge chamber outer shell water inlet; 902. Water-cooled discharge chamber outer shell water outlet; 10. Pre-focusing coil; 11. Coaxial coil; 12. Coil water-cooling unit; 121. Coil water-cooling unit water inlet; 122. Coil water-cooling unit water outlet; 13. Main focusing coil; 14. Scanning coil; 15. Water-cooled beam guiding channel; 151. Water-cooled beam guiding channel water inlet; 152. Water-cooled beam guiding channel water outlet; 153. Mounting flange. Detailed implementation manners

[0039] The present invention will be further described in conjunction with the accompanying drawings.

[0040] Aiming at the current situation that it is difficult to obtain a uniform laminar flow along the wall layer in the gas discharge chamber of the gas discharge electron gun, and the occurrence and disappearance times of the arc discharge phenomenon in the gas discharge chamber are not detected in time, resulting in unstable beam output. The present invention discloses a high-power gas discharge electron gun, which is provided with a porous gas flow guiding assembly to ensure that the gas input into the gas discharge chamber is evenly distributed along the inner wall of the gas discharge chamber in a laminar flow state, reducing the occurrence probability of low-voltage large-current arc discharge; and an arc discharge infrared detection unit is arranged near the gas discharge chamber to quickly detect the occurrence and disappearance times of the low-voltage large-current arc discharge, and feed the detected signal back to the power control system to realize the rapid shutdown and startup of the high-voltage output, which can not only protect the electron gun and the power system, but also keep the power output stable, meeting the requirement of the special processing field for the stable output of several hundred kilowatt high-power electron beam.

[0041] As Figure 1 、 Figure 2As shown in the figure, the high-power gas discharge electron gun of the present invention includes a water-cooled discharge chamber outer shell 9, a cathode 1 and an anode 2 placed in the water-cooled discharge chamber outer shell 9. The cathode 1 is connected to a negative high voltage, the anode 2 is grounded, and the water-cooled discharge chamber outer shell 9 is grounded. One end of the cathode 1 facing the anode 2 is an inwardly concave spherical structure, and the anode 2 is a funnel-shaped structure. The outer edge width of the anode 2 at the end facing the cathode 1 is greater than the outer edge width of the anode 2 at the end away from the cathode 1. The gap between the outer edge of the anode 2 at the end facing the cathode 1 and the inner wall of the water-cooled discharge chamber outer shell 9 is less than 1 mm. An arc starting boss 4 is provided on the inner wall of the water-cooled discharge chamber outer shell 9. The inner edge of the arc starting boss 4 is parallel to the outer edge of the end of the cathode 1 facing the anode 2, and the distance between the inner edge of the arc starting boss 4 and the outer edge of the end of the cathode 1 facing the anode 2 is not less than 10 mm. The space jointly surrounded by the anode 2, the cathode 1, the arc starting boss 4, and the water-cooled discharge chamber outer shell 9 is a discharge chamber.

[0042] The water-cooled discharge chamber outer shell 9 is a hollow structure, provided with a water-cooled discharge chamber outer shell water inlet 901 and a water-cooled discharge chamber outer shell water outlet 902 to provide water cooling for the water-cooled discharge chamber outer shell 9.

[0043] The cathode 1 is a hollow structure. The cathode 1 is connected to a cathode water cooling system through a cathode water inlet 102 and a cathode water outlet 103. The cathode water cooling system provides independent water cooling for the cathode 1, and the water used is deionized water.

[0044] One end of the water-cooled discharge chamber outer shell 9 where the cathode 1 is installed inside is provided with an insulator 3. The cathode 1 is fixedly installed on one end of the insulator 3 facing the anode 2. The insulator 3 effectively insulates the cathode 1 from the water-cooled discharge chamber outer shell 9. The insulator 3 can ensure that the withstand voltage between the cathode 1 and the water-cooled discharge chamber outer shell 9 is not less than 30 kV. A top convex edge is provided at one end of the insulator 3 away from the anode 2. The top convex edge of the insulator 3 is hermetically connected to the water-cooled discharge chamber outer shell 9, and a plurality of convex platforms are provided on the surface of the insulator 3 from the top convex edge to the installation end face of the cathode 1 and facing the inner wall of the water-cooled discharge chamber outer shell 9 to increase the creepage distance. The insulator 3 is also hermetically connected to the cathode 1 through a sealing assembly 101. Specifically: the cathode water inlet 102 and the cathode water outlet 103 pass through the insulator 3 and the sealing assembly 101 and are connected to the cathode water cooling system. The cathode 1 is located in the space formed by the insulator 3 and the water-cooled discharge chamber outer shell 9, and the cathode water cooling system is located outside the space formed by the insulator 3 and the water-cooled discharge chamber outer shell 9. At this time, the environment where the cathode 1 is located is a vacuum environment, and the environment where the cathode water cooling system is located is an atmospheric environment. The sealing assembly 101 can prevent vacuum leakage; at the same time, the cathode 1 has water cooling in its hollow structure, and the sealing assembly 101 can play a role in waterproofing.

[0045] The top convex edge of the insulator 3 located inside the water-cooled discharge chamber outer shell 9 is provided with an internal infrared receiving diode group 5 facing the inner side of the discharge chamber. The internal infrared receiving diode group 5 includes at least 4 infrared detection diodes. The detection signals of the infrared detection diodes are introduced into an external detection circuit 6 through a vacuum aviation plug, and the vacuum aviation plug can isolate the atmospheric environment and the vacuum environment. In an embodiment of the present invention, in order to reduce interference and make the connection wires as short as possible, the external detection circuit 6 and the internal infrared receiving diode group 5 are respectively located at corresponding positions on both sides of the top convex edge of the insulator 3. The external detection circuit 6 includes a number of comparator circuits. The number of comparator circuits is the same as the number of infrared detection diodes and the comparator circuits are in one-to-one correspondence with the infrared detection diodes. The structures of the comparator circuits are all the same. Each comparator circuit includes 1 comparator. The positive input terminal of the comparator is connected to the VCC positive voltage through 1 resistor and grounded through 1 resistor. The negative input terminal of the comparator is connected to the positive electrode of the corresponding infrared detection diode. The positive electrode of the corresponding infrared detection diode, that is, the negative input terminal of the comparator, is connected to the VCC positive voltage through 1 resistor. The negative electrode of the corresponding infrared detection diode is grounded. The resistance values of the resistors connected to the positive input terminal and the negative input terminal of the above comparator are equal. The output terminal of the comparator is the output terminal of the corresponding comparator circuit. The output terminal of this comparator is connected to the VCC positive voltage through 1 resistor. The output terminal of the comparator is connected to the first output terminal of the external detection circuit 6 through a diode. Among them, the output terminal of the comparator is connected to the positive electrode of this diode. The first output terminal of the external detection circuit 6 is grounded through 1 resistor. The output terminal of the comparator is connected to the second output terminal of the external detection circuit 6 through a diode. Among them, the output terminal of the comparator is connected to the negative electrode of this diode. The second output terminal of the external detection circuit 6 is connected to the VCC positive voltage through 1 resistor. The internal infrared receiving diode group 5 and the external detection circuit 6 together form an arc discharge infrared detection unit.

[0046] When the gas discharge electron gun is working normally, all the infrared detection diodes are turned on. The positive input terminals of the comparators in the external detection circuit 6 are all greater than the negative input terminals, and the comparators all output high levels. The output signals of the output terminals of the comparator circuits can be represented by binary as all 1s; both the first output terminal and the second output terminal of the external detection circuit 6 output high levels, and the output signal is represented by binary as "11";

[0047] When a low - voltage and high - current arc discharge occurs in the gas - discharge electron gun, at least one infrared detection diode cannot detect the infrared light inside the discharge chamber. This infrared detection diode cannot conduct because it cannot receive infrared light, and at least one infrared detection diode can detect the arc - discharge state inside the discharge chamber. This infrared detection diode conducts because it can receive infrared light. At this time, the signal at the output terminal of the comparator circuit of the external detection circuit 6 can be represented in a binary format other than all - 1 and all - 0; the first output terminal and the second output terminal of the external detection circuit 6 output high - level and low - level respectively, and the output signal is represented in binary as "10"; when it is detected that the outputs of the first output terminal and the second output terminal are "10", it can be determined that an arc - discharge phenomenon occurs in the gas - discharge electron gun or it is in an arc - discharge state;

[0048] When the arc discharge inside the gas - discharge electron gun ends, all infrared detection diodes are not conducting. The negative input terminals of the comparators of the external detection circuit 6 are greater than the positive input terminals, and all comparators output low - level. The signal at the output terminal of the comparator circuit can be represented in binary as all - 0; the outputs of the first output terminal and the second output terminal of the external detection circuit 6 are both low - level, and the output signal is represented in binary as "00".

[0049] In an embodiment of the present invention: the built - in infrared receiving diode group 5 includes 4 infrared detection diodes, namely the first infrared detection diode 501, the second infrared detection diode 502, the third infrared detection diode 503, and the fourth infrared detection diode 504. The 4 infrared detection diodes are spaced 90° apart and are evenly distributed on a circular circuit board. The circular circuit board is arranged on the top convex edge of the insulator 3. The detection signals of the infrared detection diodes are introduced into the external detection circuit 6 through vacuum aviation plugs;

[0050] The external detection circuit 6 is provided with 4 comparator circuits, namely the first comparator circuit, the second comparator circuit, the third comparator circuit, and the fourth comparator circuit. Each comparator circuit is provided with 1 comparator, namely comparator U1, comparator U2, comparator U3, and comparator U4. The 4 comparators are respectively connected to the detection signals of the 4 infrared detection diodes. Specifically:

[0051] The positive input terminal of comparator U1 is connected to the VCC positive voltage through resistor R1, the positive input terminal of comparator U1 is grounded through resistor R2, the negative input terminal of comparator U1 is connected to the VCC positive voltage through resistor R3, and the negative input terminal of comparator U1 is connected to the positive electrode of the first infrared detection diode 501 (i.e., Figure 4 、 Figure 5 the a01 terminal in Figure 4 、 Figure 5The a02 terminal (in []) is grounded. The output terminal of comparator U1 is connected to the positive voltage of VCC through resistor R4. The output terminal of comparator U1 is connected to the anode of diode D5 and the cathode of diode D6. The cathode of diode D5 is grounded through resistor R17. The anode of diode D6 is connected to the positive voltage of VCC through resistor R18. The output terminal of comparator U1 is connected to the output terminal of the first comparator circuit, i.e., the OUT1 terminal. The cathode of diode D5 is connected to the first output terminal of the external detection circuit 6, i.e., the PTC1 terminal. The anode of diode D6 is connected to the second output terminal of the external detection circuit 6, i.e., the PTC2 terminal;

[0052] The positive input terminal of comparator U2 is connected to the positive voltage of VCC through resistor R5. The positive input terminal of comparator U2 is grounded through resistor R6. The negative input terminal of comparator U2 is connected to the positive voltage of VCC through resistor R7. The negative input terminal of comparator U2 is connected to the anode of the second infrared detection diode 502 (i.e., Figure 4 , Figure 5 the b01 terminal in []), and the cathode of the second infrared detection diode 502 (i.e., Figure 4 , Figure 5 the b02 terminal in []) is grounded. The output terminal of comparator U2 is connected to the positive voltage of VCC through resistor R8. The output terminal of comparator U2 is connected to the anode of diode D7 and the cathode of diode D8. The cathode of diode D7 is grounded through resistor R17. The anode of diode D8 is connected to the positive voltage of VCC through resistor R18. The output terminal of comparator U2 is connected to the output terminal of the second comparator circuit, i.e., the OUT2 terminal. The cathode of diode D7 is connected to the first output terminal of the external detection circuit 6, i.e., the PTC1 terminal. The anode of diode D8 is connected to the second output terminal of the external detection circuit 6, i.e., the PTC2 terminal;

[0053] The positive input terminal of comparator U3 is connected to the positive voltage of VCC through resistor R9. The positive input terminal of comparator U3 is grounded through resistor R10. The negative input terminal of comparator U3 is connected to the positive voltage of VCC through resistor R11. The negative input terminal of comparator U3 is connected to the anode of the third infrared detection diode 503 (i.e., Figure 4 , Figure 5 the c01 terminal in []), and the cathode of the third infrared detection diode 503 (i.e., Figure 4 , Figure 5 the c02 terminal in []) is grounded. The output terminal of comparator U3 is connected to the positive voltage of VCC through resistor R12. The output terminal of comparator U3 is connected to the anode of diode D9 and the cathode of diode D10. The cathode of diode D9 is grounded through resistor R17. The anode of diode D10 is connected to the positive voltage of VCC through resistor R18. The output terminal of comparator U3 is connected to the output terminal of the third comparator circuit, i.e., the OUT3 terminal. The cathode of diode D9 is connected to the first output terminal of the external detection circuit 6, i.e., the PTC1 terminal. The anode of diode D10 is connected to the second output terminal of the external detection circuit 6, i.e., the PTC2 terminal;

[0054] The positive input terminal of comparator U4 is connected to the positive voltage of VCC through resistor R13, and the positive input terminal of comparator U4 is grounded through resistor R14. The negative input terminal of comparator U4 is connected to the positive voltage of VCC through resistor R15, and the negative input terminal of comparator U4 is connected to the positive electrode of the fourth infrared detection diode 504 (i.e., Figure 4 , Figure 5 the d01 terminal in Figure 4 , Figure 5 ). The negative electrode of the fourth infrared detection diode 504 (i.e.,

[0055] the d02 terminal in

[0056] ) is grounded. The output terminal of comparator U4 is connected to the positive voltage of VCC through resistor R16. The output terminal of comparator U4 is connected to the positive electrode of diode D11 and the negative electrode of diode D12. The negative electrode of diode D11 is grounded through resistor R17, and the positive electrode of diode D12 is connected to the positive voltage of VCC through resistor R18. The output terminal of comparator U4 is connected to the output terminal of the fourth comparator circuit, i.e., the OUT4 terminal. The negative electrode of diode D11 is connected to the first output terminal of the external detection circuit 6, i.e., the PTC1 terminal, and the positive electrode of diode D12 is connected to the second output terminal of the external detection circuit 6, i.e., the PTC2 terminal.

[0055] When the gas discharge electron gun is working normally, the four infrared detection diodes 501, 502, 503, and 504 are all conducting. The positive input terminals of the four comparators U1, U2, U3, and U4 of the external detection circuit 6 are all greater than the negative input terminals. The four comparators U1, U2, U3, and U4 all output high levels. The output signals of the four comparators U1, U2, U3, and U4 (i.e., the signals of the output terminals OUT1, OUT2, OUT3, and OUT4 of the four comparator circuits) can be represented in binary as "1111"; the output terminals PTC1 and PTC2 of the external detection circuit 6 both output high levels, and the output signal is represented in binary as "11";

[0056] When a low-voltage and high-current arc discharge occurs in a gas discharge electron gun, at least one infrared detection diode fails to detect the infrared light inside the discharge chamber. This infrared detection diode cannot conduct because it cannot receive infrared light, and at least one infrared detection diode can detect the arc discharge state inside the discharge chamber. This infrared detection diode conducts because it can receive infrared light. At this time, the output signals of the four comparators U1, U2, U3, and U4 of the external detection circuit 6 can be represented in binary format except for "1111" and "0000", and can be "1000", "0100", "0010", "0001", "1100", "0110", "0011", "1001", "0101", "1010", "0111", "1101", "1110", "1011" respectively; the outputs of the PTC1 and PTC2 terminals of the external detection circuit 6 are high level and low level respectively, and the output signal is represented in binary as "10"; when it is detected that the outputs of the PTC1 and PTC2 terminals are "10", it can be determined that the gas discharge electron gun has an arc discharge phenomenon or is in an arc discharge state;

[0057] When the arc discharge inside the gas discharge electron gun ends, the four infrared detection diodes 501, 502, 503, and 504 are all non-conductive. The negative input terminals of the four comparators U1, U2, U3, and U4 of the external detection circuit 6 are all greater than the positive input terminals, and the four comparators U1, U2, U3, and U4 all output low levels. The output signals of the four comparators U1, U2, U3, and U4 can be represented in binary as "0000"; the outputs of the PTC1 and PTC2 terminals of the external detection circuit 6 are both low levels, and the output signal is represented in binary as "00".

[0058] The signals at the first output terminal and the second output terminal of the external detection circuit 6 can be connected to the host computer or the arc extinguishing circuit, which can accurately determine the occurrence time and the end time of the arc discharge of the gas discharge electron gun, and provide key parameters for the closed-loop control of the gas discharge electron gun power supply.

[0059] The output terminals of the comparator circuit of the external detection circuit 6 can also be respectively connected to the 4 I / O ports of the DSP or the single-chip microcomputer of the control system, and the occurrence time and the end time of the arc discharge of the gas discharge electron gun are judged through the program.

[0060] One end of the anode 2 far from the cathode 1 is mounted on a porous gas flow guiding assembly 8, and the porous gas flow guiding assembly 8 is hermetically connected to one end of the water-cooled discharge chamber outer shell 9 close to the anode 2. Specifically: the porous gas flow guiding assembly 8 is sequentially provided with a concave stop and a central through hole along the direction away from the cathode 1. The inner diameter of the concave stop of the porous gas flow guiding assembly 8 is larger than the inner diameter of the central through hole of the porous gas flow guiding assembly 8. One end of the anode 2 far from the cathode 1 is mounted in the concave stop of the porous gas flow guiding assembly 8. The anode 2 is also provided with a central through hole, and the central through hole of the anode 2 is on the same axis as the concave stop and the central through hole of the porous gas flow guiding assembly 8;

[0061] An air flow input port 801 is arranged on the outer side wall of the porous gas flow guiding assembly 8. There is a gap between the inner side wall of the concave stop of the porous gas flow guiding assembly 8 and the anode 2. Preferably, the gap between the outer side wall of one end of the anode 2 far from the cathode 1 and the inner side wall of the concave stop of the porous gas flow guiding assembly 8 is 1 mm, and a plurality of air flow output ports are arranged on the inner side wall of the concave stop. The air flow input port 801 is connected to the plurality of air flow output ports through the internal pipeline of the porous gas flow guiding assembly 8.

[0062] The working gas passes through the air flow input port 801 of the porous gas flow guiding assembly 8, outputs from the air flow output port and enters the gap between the anode 2 and the porous gas flow guiding assembly 8, and then passes through the gap between the anode 2 and the inner wall of the water-cooled discharge chamber outer shell 9 in a laminar flow state, and rises along the inner wall of the water-cooled discharge chamber outer shell 9 to the surface of one end of the arc starting boss 4 arranged inside the water-cooled discharge chamber outer shell 9 facing the anode 2; then it is uniformly input to the vicinity of the surface of the cathode 1 facing the anode 2 to meet the working requirements of the gas discharge electron gun.

[0063] In an embodiment of the present invention, the internal pipeline of the porous gas flow guiding assembly 8 includes a first air flow buffer pipeline 802 and a second air flow buffer pipeline 803. The first air flow buffer pipeline 802 is connected to the air flow input port 801, the second air flow buffer pipeline 803 is connected to the air flow output port, an air flow blocking wall 804 is arranged between the first air flow buffer pipeline 802 and the second air flow buffer pipeline 803, and the air flow blocking wall 804 is provided with the same number of air flow connection through holes as the air flow output ports, and the air flow connection through holes and the air flow output ports are misaligned.

[0064] Specifically: Four gas flow output ports ng1, ng2, ng3, and ng4 are provided on the inner side wall of the concave notch of the porous gas flow guiding assembly 8. The gas flow input port 801 is connected to the four gas flow output ports ng1, ng2, ng3, and ng4 through a first gas flow buffer pipe 802 and a second gas flow buffer pipe 803. A gas flow blocking wall 804 is provided between the first gas flow buffer pipe 802 and the second gas flow buffer pipe 803. The same number of gas flow connection through holes g1, g2, g3, and g4 as the gas flow output ports ng1, ng2, ng3, and ng4 are provided on the gas flow blocking wall 804. The gas flow connection through holes g1, g2, g3, and g4 are misaligned with the gas flow output ports ng1, ng2, ng3, and ng4.

[0065] One end of the porous gas flow guiding assembly 8 away from the anode 2 is installed with a water-cooled beam guiding channel 15. The water-cooled beam guiding channel 15 is coaxially and hermetically connected and fixed to the porous gas flow guiding assembly 8. A through hole for beam output is provided in the center of the water-cooled beam guiding channel 15, and the diameter of the through hole is not less than the diameter of the central through hole of the anode 2. The water-cooled beam guiding channel 15 is a hollow structure, and a water-cooled beam guiding channel water inlet 151 and a water-cooled beam guiding channel water outlet 152 are provided on the outer side wall.

[0066] One end of the water-cooled beam guiding channel 15 away from the porous gas flow guiding assembly 8 is provided with a mounting flange 153 for connecting the gas discharge electron gun to the vacuum chamber.

[0067] A pre-focusing coil 10, a coaxial coil 11, a main focusing coil 13, and a scanning coil 14 are sequentially arranged on the water-cooled beam guiding channel 15, where:

[0068] The pre-focusing coil 10 is installed at one end of the water-cooled beam guiding channel 15 close to the porous gas flow guiding assembly 8 to prevent the electron beam emitted from the holes of the anode 2 from diverging excessively in the field-free space, resulting in the abnormal output of the beam current of the gas discharge electron gun.

[0069] The coaxial coil 11 is installed at one end of the pre-focusing coil 10 away from the porous gas flow guiding assembly 8, which can adjust the position of the beam output deviating from the central axis of the gas discharge electron gun, and prevent the phenomenon that the beam deviates from the axis and the beam spot quality deteriorates due to the mechanical installation of the cathode 1 and the insulator 3 being non-coaxial with the central axis of the gas discharge electron gun.

[0070] The main focusing coil 13 is installed at one end of the coaxial coil 11 away from the pre-focusing coil 10. The main focusing coil 13 and the pre-focusing coil 10 constitute an electromagnetic focusing system of the electron optical system of the gas discharge electron gun, which is used to adjust the beam spot morphology and the electron beam energy distribution state on the workpiece surface.

[0071] To meet the requirements for the long-term stable operation of the gas discharge electron gun, a coil water cooling unit 12 is provided between the coaxial coil 11 and the main focusing coil 13 of the high-power gas discharge electron gun described above; the coil water cooling unit 12 has a hollow structure, and a coil water cooling unit water inlet 121 and a coil water cooling unit water outlet 122 are provided;

[0072] A scanning coil 14 is installed at one end of the main focusing coil 13 away from the coaxial coil 11 to realize the scanning of the electron beam on the surface of the workpiece and meet the requirements of special processes.

[0073] The working process of the high-power gas discharge electron gun of the present invention is as follows:

[0074] Step 1: Cooling water is introduced into the cathode 1. The cathode 1 is connected to a negative high-voltage power supply through a high-voltage wire 7. The anode 2, the porous gas flow guiding assembly 8, the water-cooled discharge chamber outer shell 9, the water-cooled beam guiding channel 15, etc. are all grounded;

[0075] Step 2: The working gas enters the gap between the anode 2 and the porous gas flow guiding assembly 8 through the gas input port 801 of the porous gas flow guiding assembly 8, and then passes through the gap between the anode 2 and the inner wall of the water-cooled discharge chamber outer shell 9 in a laminar flow state, rises along the inner wall of the water-cooled discharge chamber outer shell 9 to the lower end face of the arc starting boss 4 provided inside the water-cooled discharge chamber outer shell 9; and then is uniformly input near the surface of the cathode 1; due to the high-voltage electric field between the cathode 1 and the arc starting boss 4, the working gas starts to discharge here first, and then a plasma is generated between the cathode 1, a part of the inner wall of the water-cooled discharge chamber outer shell 9, and the anode 2. The positive ions in the plasma bombard the cathode 1, and the cathode 1 emits secondary electrons. The secondary electrons and the electrons in the plasma converge towards the central through hole of the anode 2 under the action of the electrostatic field formed between the cathode 1 and the anode 2, and then through the regulation of the electron optical system of the gas discharge electron gun, a beam spot morphology that meets the process requirements is obtained;

[0076] Step 3: When the gas discharge electron gun is working normally, the power control system detects that the output signal of the external detection circuit 6 is "11", and the power control system outputs the working voltage according to the setting;

[0077] Step 4: When the power control system detects that the output signal of the external detection circuit 6 is "10", that is, an arc discharge occurs inside the gas discharge electron gun, the power control system stops outputting the working voltage for 5 ms to extinguish the arc; otherwise, it jumps to Step 6;

[0078] Step 5: When the power control system detects that the output signal of the external detection circuit 6 is "00", that is, the arc discharge ends, the power control system resumes the set working voltage; otherwise, it jumps to Step 4;

[0079] Step 6: Return to Step 3 until the work is completed.

[0080] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A high-power gas discharge electron gun, characterized in that: It includes a water-cooled discharge chamber outer shell (9), a cathode (1) and an anode (2) placed in the water-cooled discharge chamber outer shell (9). One end of the cathode (1) facing the anode (2) is an inwardly concave spherical structure. The anode (2) is a funnel-shaped structure. The outer edge width of the end of the anode (2) facing the cathode (1) is greater than the outer edge width of the end of the anode (2) away from the cathode (1). An arc-starting boss (4) is provided on the inner wall of the water-cooled discharge chamber outer shell (9). The inner edge of the arc-starting boss (4) is parallel to the outer edge of the end of the cathode (1) facing the anode (2). An insulator (3) is installed at one end of the water-cooled discharge chamber outer shell (9) where the cathode (1) is disposed. The cathode (1) is installed on one end of the insulator (3) facing the anode (2). The insulator (3) is hermetically connected to the cathode (1) through a sealing assembly. A top convex edge is provided at one end of the insulator (3) away from the anode (2). The top convex edge of the insulator (3) is hermetically connected to the water-cooled discharge chamber outer shell (9). An internal infrared receiving diode group (5) is provided on the top convex edge of the insulator (3) located inside the water-cooled discharge chamber outer shell (9) facing the inner side of the water-cooled discharge chamber outer shell (9). The internal infrared receiving diode group (5) includes a number of infrared detection diodes. The detection signals of the infrared detection diodes are introduced into an external detection circuit (6). One end of the anode (2) away from the cathode (1) is installed on a porous gas flow guiding assembly (8). The porous gas flow guiding assembly (8) is hermetically connected to one end of the water-cooled discharge chamber outer shell (9) close to the anode (2). The porous gas flow guiding assembly (8) is sequentially provided with a concave stop and a central through hole along the direction away from the cathode (1). One end of the anode (2) away from the cathode (1) is installed in the concave stop of the porous gas flow guiding assembly (8). There is a gap between the inner side wall of the concave stop of the porous gas flow guiding assembly (8) and the anode (2). The anode (2) is also provided with a central through hole. The central through hole of the anode (2) is on the same axis as the concave stop and the central through hole of the porous gas flow guiding assembly (8). An air flow input port (801) is provided on the outer side wall of the porous gas flow guiding assembly (8). A number of air flow output ports are provided on the inner side wall of the concave stop of the porous gas flow guiding assembly (8). The air flow input port (801) is connected to the air flow output ports through the internal pipeline of the porous gas flow guiding assembly (8).

2. The high-power gas discharge electron gun according to claim 1, wherein: The external detection circuit (6) includes a number of comparator circuits. The number of comparator circuits is the same as the number of infrared detection diodes and the comparator circuits correspond to the infrared detection diodes one by one. The structures of the comparator circuits are all the same. Each comparator circuit includes 1 comparator. The positive input terminal of the comparator is connected to the positive VCC voltage through 1 resistor and grounded through 1 resistor. The negative input terminal of the comparator is connected to the positive electrode of the corresponding infrared detection diode. The negative input terminal of the comparator is connected to the positive VCC voltage through 1 resistor, and the negative electrode of the corresponding infrared detection diode is grounded. The output terminal of the comparator is the output terminal of the corresponding comparator circuit. The output terminal of this comparator is connected to the positive VCC voltage through 1 resistor. The output terminal of the comparator is connected to the first output terminal of the external detection circuit (6) through a diode. The output terminal of the comparator is connected to the positive electrode of this diode. The first output terminal of the external detection circuit (6) is grounded through 1 resistor. The output terminal of the comparator is also connected to the second output terminal of the external detection circuit (6) through a diode. The output terminal of the comparator is connected to the negative electrode of this diode. The second output terminal of the external detection circuit (6) is connected to the positive VCC voltage through 1 resistor.

3. A high-power gas discharge electron gun according to claim 1, characterized in that: The outer edge of one end of the anode (2) facing the cathode (1) has a gap less than 1 mm with the inner wall of the water-cooled discharge chamber outer shell (9); The distance between the inner edge of the arc starting boss (4) and the outer edge of the end of the cathode (1) facing the anode (2) is not less than 10 mm.

4. A high-power gas discharge electron gun according to claim 1, characterized in that: The water-cooled discharge chamber outer shell (9) is a hollow structure and is provided with a water-cooled discharge chamber outer shell water inlet (901) and a water-cooled discharge chamber outer shell water outlet (902); The cathode (1) is a hollow structure and is provided with a cathode water inlet (102) and a cathode water outlet (103).

5. A high-power gas discharge electron gun according to claim 1, characterized in that: The internal pipeline of the porous gas flow guiding assembly (8) includes a first gas flow buffer pipeline (802) and a second gas flow buffer pipeline (803). The first gas flow buffer pipeline (802) is connected to the gas flow input port (801). The second gas flow buffer pipeline (803) is connected to the gas flow output port. An air flow blocking wall (804) is arranged between the first gas flow buffer pipeline (802) and the second gas flow buffer pipeline (803). Air flow connection through holes are arranged on the air flow blocking wall (804).

6. A high-power gas discharge electron gun according to claim 1, characterized in that: A number of bosses are arranged on the surface from the top convex edge of the insulator (3) to the installation end face of the cathode (1) facing the inner wall of the water-cooled discharge chamber outer shell (9).

7. A high-power gas discharge electron gun according to claim 1, characterized in that: One end of the porous gas flow guiding assembly (8) away from the anode (2) is installed with a water-cooled beam guiding channel (15). The water-cooled beam guiding channel (15) is coaxially and hermetically connected and fixed with the porous gas flow guiding assembly (8). A through hole is arranged in the center of the water-cooled beam guiding channel (15), and the diameter of the through hole is not less than the diameter of the central through hole of the anode (2); A pre-focusing coil (10), a coaxial coil (11), a main focusing coil (13) and a scanning coil (14) are sequentially arranged on the water-cooled beam guiding channel (15), where: The pre-focusing coil (10) is installed at one end of the water-cooled beam guiding channel (15) close to the porous gas flow guiding assembly (8); An alignment coil (11) is installed at one end of the pre-focusing coil (10) far from the porous gas flow guiding assembly (8); A main focusing coil (13) is installed at one end of the alignment coil (11) far from the pre-focusing coil (10); A scanning coil (14) is installed at one end of the main focusing coil (13) far from the alignment coil (11).

8. The high-power gas discharge electron gun according to claim 7, wherein: A coil water cooling unit (12) is arranged between the alignment coil (11) and the main focusing coil (13); the coil water cooling unit (12) is provided with a coil water cooling unit water inlet (121) and a coil water cooling unit water outlet (122).

9. The high-power gas discharge electron gun according to claim 7, characterized in that: The water-cooled beam guiding channel (15) is of a hollow structure and is provided with a water-cooled beam guiding channel water inlet (151) and a water-cooled beam guiding channel water outlet (152).

10. A high-power gas discharge electron gun according to claim 7, characterized in that: An installation flange is arranged at one end of the water-cooled beam guiding channel (15) far from the porous gas flow guiding assembly (8).

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