A power supply device for an indirect thermal electron gun and a method of using the same

Abstract

The present invention discloses a power supply device for an inter-thermal electron gun and a method for using the same. The negative end of the high-voltage acceleration power supply unit is connected to the tungsten needle of the inter-thermal electron gun through a current limiting resistor, the negative end of the gas discharge regulation circuit is connected to the aluminum cathode, the negative end of the grid voltage regulation circuit is connected to the grid, the positive ends of the gas discharge regulation circuit and the grid voltage regulation circuit are respectively connected to one point through a resistor and are at the same potential as the tungsten needle, the output voltage of the gas discharge regulation circuit can adjust the thermal emission state of the tungsten needle, the output voltage of the grid voltage regulation circuit is used to adjust the amount of electrons passing through the grid hole, and the high-voltage acceleration power supply unit is used to adjust the speed of the electrons passing through the grid hole to the anode. The power supply device of the present invention has a reduced number of circuits, and the design and manufacturing costs are reduced; the topology circuit of the power supply device is simplified, and the design difficulty of the power supply device is reduced; it is conducive to improving the anti-interference ability of the power supply device.

Description

Technical Field

[0001] The invention belongs to the technical field of electron guns, and in particular relates to a power supply device of an indirect thermal electron gun and a use method thereof. Background Art

[0002] Electron beam processing technology has been widely used in defense industries such as aerospace, weapons, and civilian industries. In recent years, the development of electron beam processing technology has been more rapid, especially in the field of electron beam additive manufacturing technology, which has attracted worldwide attention. The corresponding electron beam additive manufacturing equipment technology has also developed rapidly.

[0003] Electron beam additive manufacturing equipment includes electron beam selective melting additive manufacturing equipment and electron beam fuse deposition additive manufacturing equipment. In recent years, in order to meet the needs of rapid preparation of large and complex metal structures in the aerospace and other defense industries, both electron beam selective melting additive manufacturing equipment and electron beam fuse deposition additive manufacturing equipment require that their electron beam sources can work stably for a long time and have higher requirements on their reliability during the working process.

[0004] The electron beam source of existing electron beam additive manufacturing equipment generally adopts a directly heated electron gun or an indirectly heated electron gun. The directly heated electron gun usually adopts a sheet filament, which is directly heated by a filament heating power supply to emit electrons, and the beam current is regulated by a grid power supply, and an accelerating power supply is used to accelerate the electrons; the indirectly heated electron gun usually needs to use a filament heating power supply to output current to heat the mosquito coil disc or spiral filament, and apply a bombardment voltage generated by a bombardment power supply between the filament and the cathode, so that the filament generates electrons to bombard the cathode and then emit electrons. The number of electrons emitted through the grid hole to reach the anode is determined by the voltage applied to the grid by the grid power supply. A negative high voltage output by the accelerating power supply is applied between the grid and the anode, which will generate an electrostatic field, and the electrostatic field accelerates the electrons passing through the grid hole.

[0005] When a directly heated electron gun outputs a high-power beam, it requires a large output current of the filament heating power supply, generally reaching tens of amperes, which places stringent requirements on the design of high-voltage transmission and filament heating power supplies; although the output current of the filament heating power supply of an indirectly heated electron gun is not large when a high-power beam is output, it requires a large bombardment current provided by the bombardment power supply. A large bombardment current can easily cause the cathode (tungsten block) to break down, making it impossible to output the beam normally, and the high-voltage cable must have at least four conductors to meet the requirements; the power supply of a conventional indirectly heated electron gun requires at least a filament heating power supply, a bombardment power supply, a grid (bias) power supply, and an acceleration power supply to meet the requirements of normal electron beam output. Therefore, the power supply design and manufacturing technology of a conventional indirectly heated electron gun is difficult, and the beam control method is cumbersome and difficult.

[0006] The existing electron guns for electron beam additive manufacturing, whether they are direct-heated or indirect-heated, all have filaments. Even if the filaments are treated with special processes, no matter which structure, long-term use in the harsh vacuum environment of electron beam additive manufacturing with high metal vapor contamination will inevitably lead to limited cathode life. Long-term use is prone to cathode deformation, resulting in poor beam quality, which in turn affects the quality of large-scale metal structure additive manufacturing. In view of the urgent need for electron beam additive manufacturing of large and complex metal structures in the current aerospace field, it is imperative to develop an electron gun with high operating voltage, long cathode life, small beam spot, and high electron beam energy density. In view of the above problems, based on the in-depth study of the electron excitation mode of commonly used electron guns, and combining the advantages of existing indirect thermal electron guns and cold cathode gas discharge electron gun technologies, an indirect thermal electron gun based on gas discharge was invented. The positive ions in the plasma generated by the discharge of the working gas in the electron gun bombard the aluminum cathode, and the aluminum cathode emits secondary electrons. The secondary electrons are accelerated by the electrostatic field formed by the aluminum cathode and the tungsten needle and bombard the tungsten needle, converting kinetic energy into thermal energy, heating the tungsten needle, so that the tungsten needle reaches a thermal emission state to emit electrons, and the size of the electron beam emitted by the tungsten needle is regulated by the negative voltage of the gate, and then the electrons are accelerated by the high-voltage electric field formed by the gate and the anode, wherein the anode is grounded. Therefore, how to design a power supply device for the above-mentioned indirect thermal electron gun that can excite electrons through gas discharge and regulate the amount of electrons generated and accelerate electrons has become an urgent problem to be solved. Summary of the invention

[0007] Purpose of the invention: In view of the problems existing in the prior art, the present invention discloses a power supply device of an indirect thermal electron gun and a method of using the same.

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

[0009] A power supply device for an indirect thermal electron gun includes a high-voltage acceleration power supply unit, a main control unit, a gas discharge regulation circuit, a grid voltage regulation circuit, a signal conversion circuit, an isolation power supply circuit and an optical fiber group, wherein:

[0010] The positive output end of the high-voltage acceleration power supply unit is connected to the first end of the beam sampling resistor R3, and the second end of the beam sampling resistor R3 is grounded and connected to the vacuum chamber;

[0011] The negative output end of the high-voltage acceleration power supply unit is connected to the first end of the current limiting resistor R0, the second end of the current limiting resistor R0 is connected to the tungsten needle, the second end of the current limiting resistor R0 is connected to the first end of the voltage dividing resistor R4, the second end of the voltage dividing resistor R4 is connected to the first end of the sampling resistor R5, the second end of the sampling resistor R5 is connected to the positive output end of the high-voltage acceleration power supply unit, the first end and the second end of the sampling resistor R5 are both connected to the main control unit, and the main control unit is also connected to the high-voltage acceleration power supply unit and the isolation power supply circuit;

[0012] The second end of the current limiting resistor R0 is connected to the first end of the voltage dividing resistor R1, the second end of the voltage dividing resistor R1 is connected to the positive output end of the gas discharge regulating circuit, the negative output end of the gas discharge regulating circuit is connected to the aluminum cathode, and the gas discharge regulating circuit is connected to the signal conversion circuit;

[0013] The second end of the current limiting resistor R0 is connected to the first end of the voltage dividing resistor R2, the second end of the voltage dividing resistor R2 is connected to the positive output end of the gate voltage regulating circuit, the negative output end of the gate voltage regulating circuit is connected to the gate, and the gate voltage regulating circuit is connected to the signal conversion circuit;

[0014] The second end of the current limiting resistor R0 is connected to the negative output end of the isolation power supply circuit, the first output end of the isolation power supply circuit is connected to the gas discharge regulation circuit and the gate voltage regulation circuit, and the second output end of the isolation power supply circuit is connected to the signal conversion circuit;

[0015] The signal conversion circuit is connected to the main control unit via an optical fiber group.

[0016] Preferably, the high-voltage acceleration power supply unit includes a first rectifier circuit, a first inverter circuit, a voltage doubler rectifier circuit, a first PWM regulation circuit and a first step-up transformer; wherein:

[0017] The input end of the first rectifier circuit is connected to a three-phase 380V AC power, the output end of the first rectifier circuit is connected to the input end of the first inverter circuit, the output end of the first inverter circuit is connected to the input end of the first step-up transformer, the output end of the first step-up transformer is connected to the input end of the voltage-doubling rectifier circuit, the positive output end of the voltage-doubling rectifier circuit serves as the positive output end of the high-voltage acceleration power supply unit, the negative output end of the voltage-doubling rectifier circuit serves as the negative output end of the high-voltage acceleration power supply unit, and the first PWM regulation circuit is connected to the first inverter circuit and the main control unit.

[0018] Preferably, the main control unit includes a DSP main control and a first PID adjustment circuit, a first voltage / frequency and frequency / voltage signal conversion circuit, a first optical fiber signal receiving terminal, a second optical fiber signal receiving terminal, a third optical fiber signal receiving terminal, a first optical fiber signal transmitting terminal, a second optical fiber signal transmitting terminal and a fourth optical fiber signal receiving terminal; wherein:

[0019] The DSP main control and the first PID adjustment circuit are connected to the first voltage / frequency and frequency / voltage signal conversion circuit, and the first voltage / frequency and frequency / voltage signal conversion circuit is connected to the output ends of the first optical fiber signal receiving terminal, the second optical fiber signal receiving terminal, the third optical fiber signal receiving terminal, and the fourth optical fiber signal receiving terminal and the input ends of the first optical fiber signal transmitting terminal and the second optical fiber signal transmitting terminal;

[0020] The DSP main control and the first PID adjustment circuit are connected to the high-voltage acceleration power supply unit and the first and second ends of the sampling resistor R5, the first voltage / frequency and frequency / voltage signal conversion circuit is connected to the isolation power supply circuit, and the input ends of the first optical fiber signal receiving terminal, the second optical fiber signal receiving terminal, the third optical fiber signal receiving terminal, and the fourth optical fiber signal receiving terminal and the output ends of the first optical fiber signal transmitting terminal and the second optical fiber signal transmitting terminal are respectively connected to the signal conversion circuit through optical fibers.

[0021] Preferably, the isolated power supply circuit includes a second rectifier circuit, a second inverter circuit, an isolation transformer, an isolated rectifier circuit, a second PID regulation circuit, a second PWM regulation circuit, a second Hall current sensor, and a second Hall voltage sensor; the isolation transformer includes a primary winding, a first secondary winding, and a second secondary winding; wherein:

[0022] The input end of the second rectifier circuit is connected to a three-phase 380V AC power, the output end of the second rectifier circuit is connected to the input end of the second inverter circuit, the output end of the second inverter circuit is connected to the primary winding of the isolation transformer, the first secondary winding of the isolation transformer is connected to the input end of the isolation rectifier circuit, the output end of the isolation rectifier circuit serves as the first output end of the isolation power supply circuit, and the second secondary winding of the isolation transformer serves as the second output end of the isolation power supply circuit; the second Hall current sensor collects the output current of the second inverter circuit and sends it to the second PID regulation circuit; the second Hall voltage sensor collects the output voltage of the isolation rectifier circuit, i.e., the first isolation voltage feedback electrical signal, and sends it to the signal conversion circuit; the second PID regulation circuit is connected to the second PWM regulation circuit and the main control unit, and the second PWM regulation circuit is connected to the second inverter circuit.

[0023] Preferably, the gas discharge regulation circuit includes a third inverter circuit, a third boost transformer, a third rectifier circuit, a third Hall current sensor, a third Hall voltage sensor, a third PID regulation circuit and a third PWM regulation circuit; wherein:

[0024] The input end of the third inverter circuit is connected to the first output end of the isolation power supply circuit, the output end of the third inverter circuit is connected to the input end of the third step-up transformer, the output end of the third step-up transformer is connected to the input end of the third rectifier circuit, the negative output end of the third rectifier circuit serves as the negative output end of the gas discharge regulation circuit, the positive output end of the third rectifier circuit serves as the positive output end of the gas discharge regulation circuit, the third Hall current sensor collects the current at the positive output end of the third rectifier circuit, i.e., the first gas discharge current feedback electrical signal and inputs it into the third PID regulation circuit and the signal conversion circuit, the third Hall voltage sensor collects the output end voltage of the third rectifier circuit, i.e., the first gas discharge voltage feedback electrical signal and inputs it into the third PID regulation circuit and the signal conversion circuit, the third PID regulation circuit is connected to the third PWM regulation circuit and the signal conversion circuit, and the third PWM regulation circuit is connected to the third inverter circuit.

[0025] Preferably, the gate voltage regulation circuit includes a fourth inverter circuit, a fourth boost transformer, a fourth rectifier circuit, a fourth Hall current sensor, a fourth Hall voltage sensor, a fourth PID regulation circuit and a fourth PWM regulation circuit; wherein:

[0026] The input end of the fourth inverter circuit is connected to the first output end of the isolation power supply circuit, the output end of the fourth inverter circuit is connected to the input end of the fourth step-up transformer, the output end of the fourth step-up transformer is connected to the input end of the fourth rectifier circuit, the negative output end of the fourth rectifier circuit serves as the negative output end of the gate voltage regulation circuit, the positive output end of the fourth rectifier circuit serves as the positive output end of the gate voltage regulation circuit, the fourth Hall current sensor collects the current at the positive output end of the fourth rectifier circuit and inputs it into the fourth PID regulation circuit, the fourth Hall voltage sensor collects the output end voltage of the fourth rectifier circuit, that is, the first gate voltage feedback electrical signal and inputs it into the fourth PID regulation circuit and the signal conversion circuit, the fourth PID regulation circuit is connected to the fourth PWM regulation circuit and the signal conversion circuit, and the fourth PWM regulation circuit is connected to the fourth inverter circuit.

[0027] Preferably, the signal conversion circuit includes a second voltage / frequency and frequency / voltage signal conversion circuit, a third optical fiber signal transmitting terminal, a fourth optical fiber signal transmitting terminal, a fifth optical fiber signal transmitting terminal, a fifth optical fiber signal receiving terminal, a sixth optical fiber signal receiving terminal, a sixth optical fiber signal transmitting terminal, a power supply rectification circuit and a DC / DC conversion circuit; wherein:

[0028] The input end of the power supply rectifier circuit is connected to the second output end of the isolation power supply circuit, the output end of the power supply rectifier circuit is connected to the input end of the DC / DC conversion circuit, the output end of the DC / DC conversion circuit is connected to the second voltage / frequency and frequency / voltage signal conversion circuit, and the second voltage / frequency and frequency / voltage signal conversion circuit is connected to the input ends of the third optical fiber signal transmitting terminal, the fourth optical fiber signal transmitting terminal, the fifth optical fiber signal transmitting terminal, and the sixth optical fiber signal transmitting terminal, and the output ends of the fifth optical fiber signal receiving terminal and the sixth optical fiber signal receiving terminal;

[0029] The negative output end of the power supply rectifier circuit, the reference ground of the DC / DC conversion circuit and the second voltage / frequency and frequency / voltage signal conversion circuit are all connected to the second end of the current limiting resistor R0, the second voltage / frequency and frequency / voltage signal conversion circuit is also connected to the isolation power supply circuit, the gas discharge regulation circuit and the gate voltage regulation circuit, and the output ends of the third optical fiber signal transmitting terminal, the fourth optical fiber signal transmitting terminal, the fifth optical fiber signal transmitting terminal and the sixth optical fiber signal transmitting terminal and the input ends of the fifth optical fiber signal receiving terminal and the sixth optical fiber signal receiving terminal are respectively connected to the main control unit through optical fibers.

[0030] Preferably, it also includes an oil tank, which is filled with insulating oil, and the voltage doubling rectifier circuit of the high-voltage acceleration power supply unit, the first step-up transformer, the isolation transformer of the isolation power supply circuit, the isolation rectifier circuit, the gas discharge regulation circuit, the gate voltage regulation circuit and the signal conversion circuit are immersed in the insulating oil.

[0031] Preferably, the main control unit is also connected to a gas flow controller and a focusing coil driving circuit.

[0032] A method for using a power supply device of an indirect thermal electron gun comprises the following steps:

[0033] S1. When the vacuum degree of the vacuum chamber where the workpiece is located and the inter-thermal electron gun reaches the set requirements, and the water cooling pressure and the compressed air pressure reach the set requirements, the three-phase AC power is started to supply power to the power supply device, the isolated power supply circuit works normally, the isolated rectifier circuit outputs 500V DC, and the second voltage / frequency and frequency / voltage signal conversion circuit obtains ±15V power supply;

[0034] The main control unit sets the second gate voltage to an electrical signal U bg2 Set to the maximum, and obtain the first grid voltage given electrical signal U through the first voltage / frequency and frequency / voltage signal conversion circuit, optical fiber, and the second voltage / frequency and frequency / voltage signal conversion circuit. bg , and then transmitted to the fourth PID regulation circuit, so that each component in the gate voltage regulation circuit works normally, and then the gate voltage connected to the negative output terminal of the gate voltage regulation circuit reaches -2000V;

[0035] At the same time, the main control unit energizes the main focusing coil through the focusing coil driving circuit according to the default value of the system setting;

[0036] S2, the main control unit detects whether there is a high-voltage given electrical signal U from the host computer HVg , if there is a high voltage given electrical signal U HVg , the main control unit gives an electrical signal U according to the high voltage HVg , the high voltage feedback electrical signal U at the first end of the sampling resistor R5 HV PID regulation is performed, and the regulated signal is sent to the first PWM regulation circuit to control the on / off of the power switch tube in the first inverter circuit, so that the 500V DC obtained after rectification by the first rectifier circuit is converted into an AC with an inverter frequency of 20kHz and adjustable amplitude, and then the AC is obtained after the first step-up transformer steps up and the voltage doubler rectifier circuit rectifies to obtain the high-voltage given electrical signal U HVg The consistent negative high voltage then enables the tungsten needle connected to the negative output terminal of the voltage doubler rectifier circuit through the current limiting resistor R0 to obtain a negative high voltage;

[0037] S3, the main control unit detects whether there is a beam current setting electrical signal U from the host computer Ibg , if there is a beam current given electrical signal U Ibg , then jump to S5; otherwise, check whether there is an initial electrical signal U of the gas discharge voltage from the host computer ggw If not, jump to S2; otherwise, execute S4;

[0038] S4, the main control unit turns on the gas flow controller to introduce working gas into the internal of the thermal electron gun, and the main control unit turns on the gas discharge voltage initial electrical signal U ggw , the second gas discharge voltage is given as an electrical signal U gg2 Assume that the initial electrical signal of the gas discharge voltage is U ggw , the second gas discharge voltage is given as an electrical signal U gg2 After passing through the first voltage / frequency and frequency / voltage signal conversion circuit, the optical fiber, and the second voltage / frequency and frequency / voltage signal conversion circuit, a new first gas discharge voltage given electrical signal U is obtained. gg , and then transmitted to the third PID regulating circuit, so that each component in the gas discharge regulating circuit works normally, and then the aluminum cathode voltage connected to the negative output end of the gas discharge regulating circuit is connected to the second gas discharge voltage given electrical signal U gg2 The corresponding actual gas discharge voltage is the same, and the second gas discharge current feedback electrical signal I is fed back to the main control unit. gf2 , judge the thermal emission state of the electrons emitted by the tungsten needle and jump to S8;

[0039] S5, the main control unit turns on the gas flow controller to introduce the working gas into the internal of the thermal electron gun, and at the same time the main control unit gives the system default second gas discharge voltage given electrical signal U gg2 , a new first gas discharge voltage given electrical signal U is obtained through the first voltage / frequency and frequency / voltage signal conversion circuit, the optical fiber, and the second voltage / frequency and frequency / voltage signal conversion circuit. gg , and then transmitted to the third PID regulating circuit, so that each component in the gas discharge regulating circuit works normally, and then the aluminum cathode voltage connected to the negative output end of the gas discharge regulating circuit is connected to the second gas discharge voltage given electrical signal U gg2 The corresponding actual gas discharge voltage is the same;

[0040] There is a negative voltage of several thousand volts between the aluminum cathode and the tungsten needle, which causes the working gas between the aluminum cathode and the tungsten needle to discharge and form plasma. The positive ions in the plasma bombard the surface of the aluminum cathode, stimulating secondary electrons to bombard the tungsten needle. The secondary electrons convert kinetic energy into thermal energy, heating the tungsten needle to a thermal emission state that emits electrons.

[0041] The thermal emission state of the tungsten needle emitting electrons is fed back as an electrical signal I through the first gas discharge current. gf The first gas discharge current feedback electrical signal I gf After passing through the second voltage / frequency and frequency / voltage signal conversion circuit, the optical fiber, and the first voltage / frequency and frequency / voltage signal conversion circuit, a second gas discharge current feedback electrical signal I is obtained. gf2 The data table of the corresponding relationship between the gas flow rate, the gas discharge voltage, the gas discharge current and the beam current is stored in the memory of the DSP main control and the first PID adjustment circuit. After looking up the table, the gas flow rate set value is obtained, and the main control unit resets the gas flow rate of the gas flow controller so that the first gas discharge current feedback electrical signal I gf Reaching a set state;

[0042] S6. The main control unit gives an electrical signal U according to the beam current. Ibg , beam feedback electrical signal U Ib PID regulation is performed, and the signal after PID regulation passes through the first voltage / frequency and frequency / voltage signal conversion circuit, the optical fiber, and the second voltage / frequency and frequency / voltage signal conversion circuit to obtain a new first grid voltage given electrical signal U bg , and then transmitted to the fourth PID adjustment circuit to make each component in the grid voltage adjustment circuit work normally, and then adjust the grid voltage to make the beam feedback electrical signal U at the first end of the beam sampling resistor R3 Ib With the beam current given electrical signal U Ibg be consistent;

[0043] S7, check whether there is a stop signal from the host computer. If no stop signal is detected, jump to S2; otherwise, if a stop signal is detected, jump to S9;

[0044] S8, detect whether there is a gas discharge voltage initial electrical signal U from the host computer ggw , if yes, jump to S4, otherwise jump to S2;

[0045] S9, the main control unit will not consider the high voltage given electrical signal U HVg , directly set the signal sent to the first PWM regulation circuit to zero, so that the output of the high-voltage acceleration power supply unit is zero, and the second gas discharge voltage is given by the electrical signal U gg2 and the second gate voltage given electrical signal U bg2 Set it to 0, so that the output of the gas discharge regulation circuit and the grid voltage regulation circuit is zero, turn off the gas flow controller and the focusing coil drive circuit, and then turn off the three-phase AC power.

[0046] Beneficial effects: Compared with the prior art, the present invention has the following significant beneficial effects:

[0047] The power supply device of the present invention has a negative end of a high-voltage acceleration power supply unit connected to a tungsten needle of an inter-thermal electron gun through a current limiting resistor, a negative end of a gas discharge regulating circuit connected to an aluminum cathode, a negative end of a grid voltage regulating circuit connected to a grid, positive ends of the gas discharge regulating circuit and the grid voltage regulating circuit connected to one point through resistors respectively, and at the same potential as the tungsten needle, an output voltage of the gas discharge regulating circuit can regulate the thermal emission state of the tungsten needle, an output voltage of the grid voltage regulating circuit is used to regulate the amount of electrons passing through the grid hole, and a high-voltage acceleration power supply unit is used to regulate the speed of electrons reaching the anode through the grid hole; the power supply device has the following advantages:

[0048] 1. Only a high-voltage acceleration power supply unit as an acceleration power supply, a gas discharge regulation circuit as a gas discharge power supply, and a gate voltage regulation circuit as a gate power supply are needed, so the number of circuits is reduced and the design and manufacturing cost is reduced;

[0049] 2. An isolated power supply circuit is used to supply power to the gas discharge regulation circuit, the gate voltage regulation circuit and the signal conversion circuit, which simplifies the topology circuit of the power supply device and reduces the design difficulty of the power supply device;

[0050] 3. The gas discharge voltage, gas discharge current, gate voltage, and output voltage of the isolated power supply circuit are collected at the output ends of the gas discharge regulation circuit, the gate voltage regulation circuit, and the isolated power supply circuit connected to the negative high voltage, respectively. The gas discharge power supply output voltage and current, the gate voltage, and the output voltage of the isolated power supply circuit are transmitted to the control system of the power supply device by using voltage-frequency conversion, optical fiber transmission, and frequency-voltage conversion technology, which is beneficial to improving the anti-interference ability of the power supply device. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a schematic diagram of the connection between the power supply device and the electron gun of the present invention;

[0052] Figure 2 It is a circuit diagram of a high-voltage acceleration power supply unit of the power supply device of the present invention and some peripheral circuits thereof;

[0053] Figure 3 It is a circuit diagram of the main control unit of the power supply device of the present invention and some peripheral circuits thereof;

[0054] Figure 4 It is a circuit diagram of the isolated power supply circuit and some peripheral circuits of the power supply device of the present invention;

[0055] Figure 5 It is a circuit diagram of the gas discharge regulating circuit and some peripheral circuits of the power supply device of the present invention;

[0056] Figure 6 It is a circuit diagram of a gate voltage regulating circuit and some peripheral circuits of the power supply device of the present invention;

[0057] Figure 7 It is a circuit diagram of the signal conversion circuit of the power supply device of the present invention and part of its peripheral circuits;

[0058] Wherein: 1. High-voltage acceleration power supply unit; 101. First rectifier circuit; 102. First inverter circuit; 103. Voltage doubling rectifier circuit; 104. First PWM regulation circuit; 105. First step-up transformer;

[0059] 2. Main control unit; 20. DSP main control and first PID adjustment circuit; 200. First voltage / frequency and frequency / voltage signal conversion circuit; 201. First optical fiber signal receiving terminal; 202. Second optical fiber signal receiving terminal; 203. Third optical fiber signal receiving terminal; 204. First optical fiber signal transmitting terminal; 205. Second optical fiber signal transmitting terminal; 206. Fourth optical fiber signal receiving terminal;

[0060] 3. Gas discharge regulation circuit; 301. Third inverter circuit; 302. Third step-up transformer; 303. Third rectifier circuit; 304. Third Hall current sensor; 305. Third Hall voltage sensor; 306. Third PID regulation circuit; 307. Third PWM regulation circuit;

[0061] 4. Gate voltage regulating circuit; 401. Fourth inverter circuit; 402. Fourth step-up transformer; 403. Fourth rectifier circuit; 404. Fourth Hall current sensor; 405. Fourth Hall voltage sensor; 406. Fourth PID regulating circuit; 407. Fourth PWM regulating circuit;

[0062] 5. Signal conversion circuit; 500. Second voltage / frequency and frequency / voltage signal conversion circuit; 501. Third optical fiber signal transmitting terminal; 502. Fourth optical fiber signal transmitting terminal; 503. Fifth optical fiber signal transmitting terminal; 504. Fifth optical fiber signal receiving terminal; 505. Sixth optical fiber signal receiving terminal; 506. Sixth optical fiber signal transmitting terminal; 507. Power supply rectification circuit; 508. DC / DC conversion circuit;

[0063] 6. Gas flow controller;

[0064] 7. Isolation power supply circuit; 71. Second rectifier circuit; 72. Second inverter circuit; 73. Isolation transformer; 74. Isolation rectifier circuit; 75. Second PID regulation circuit; 76. Second PWM regulation circuit; 77. Second Hall current sensor; 78. Second Hall voltage sensor; 731. Primary winding of isolation transformer; 732. First secondary winding of isolation transformer; 733. Second secondary winding of isolation transformer;

[0065] 8. Optical fiber group;

[0066] 9. Workpiece;

[0067] 10. Focusing coil driving circuit;

[0068] 11. Vacuum chamber;

[0069] 12. Thermal electron gun; 121. Aluminum cathode; 122. Tungsten needle; 123. Grid; 124. Anode; 125. Main focusing coil. DETAILED DESCRIPTION

[0070] The present invention will be further described below in conjunction with the accompanying drawings.

[0071] The present invention discloses a power supply device for a thermal electron gun, which is a power supply device capable of providing a gas discharge power supply, a grid power supply, and an acceleration power supply for a gas discharge thermal electron gun. The corresponding power supply device based on a gas discharge thermal electron gun only needs a gas discharge power supply, a grid power supply, and an acceleration power supply to meet the demand for long-term stable output of the beam. The power supply device includes a high-voltage acceleration power supply unit 1, a main control unit 2, a gas discharge regulating circuit 3, a grid voltage regulating circuit 4, a signal conversion circuit 5, an isolation power supply circuit 7, and an optical fiber group 8. Figure 1 As shown, they are connected as follows:

[0072] The positive output end of the high-voltage acceleration power supply unit 1 is connected to the first end of the beam sampling resistor R3, the second end of the beam sampling resistor R3 is grounded and connected to the vacuum chamber 11, so that the electrons emitted by the thermal electron gun 12 are connected to the positive output end of the high-voltage acceleration power supply unit 1 through the vacuum chamber 11 and the beam sampling resistor R3 to form a loop;

[0073] The negative output end of the high-voltage acceleration power supply unit 1 is connected to the first end of the current limiting resistor R0, the second end of the current limiting resistor R0 is connected to the tungsten needle 122 of the thermal electron gun 12, the second end of the current limiting resistor R0 is connected to the first end of the voltage dividing resistor R4, the second end of the voltage dividing resistor R4 is connected to the first end of the sampling resistor R5, the second end of the sampling resistor R5 is connected to the positive output end of the high-voltage acceleration power supply unit 1, and the voltage dividing resistor R4 and the sampling resistor R5 form a high-voltage sampling circuit; the first end and the second end of the sampling resistor R5 are both connected to the main control unit 2, the sampling resistor R5 transmits the sampled high-voltage signal to the main control unit 2, and the beam sampling resistor R3 transmits the collected beam signal to the main control unit 2; the main control unit 2 is also connected to the high-voltage acceleration power supply unit 1 and the isolation power supply circuit 7, the main control unit 2 changes the PWM output pulse width according to the voltage signal adjusted by the PID, and then transmits it to the first PWM adjustment circuit 104 in the high-voltage acceleration power supply unit 1, and then changes the on / off time of the power switch device in the first inverter circuit 102 in the high-voltage acceleration power supply unit 1, so as to ensure the stability of the output voltage of the high-voltage acceleration power supply unit 1;

[0074] The second end of the current limiting resistor R0 is connected to the first end of the voltage dividing resistor R1, the second end of the voltage dividing resistor R1 is connected to the positive output end of the gas discharge regulating circuit 3, the negative output end of the gas discharge regulating circuit 3 is connected to the aluminum cathode 121 of the thermal electron gun 12, the gas discharge regulating circuit 3 is connected to the signal conversion circuit 5, and the gas discharge regulating circuit 3 sends a first gas discharge current feedback electrical signal I gf , the first gas discharge voltage feedback electrical signal U gf To the signal conversion circuit 5, the signal conversion circuit 5 sends a first gas discharge voltage given electrical signal U gg To the gas discharge regulating circuit 3;

[0075] The second end of the current limiting resistor R0 is connected to the first end of the voltage dividing resistor R2, the second end of the voltage dividing resistor R2 is connected to the positive output end of the gate voltage regulating circuit 4, the negative output end of the gate voltage regulating circuit 4 is connected to the gate 123 of the thermal electron gun 12, the gate voltage regulating circuit 4 is connected to the signal conversion circuit 5, and the gate voltage regulating circuit 4 sends a first gate voltage feedback electrical signal U bf To the signal conversion circuit 5, the signal conversion circuit 5 sends a first gate voltage given electrical signal Ubg to the gate voltage regulating circuit 4;

[0076] The second end of the current limiting resistor R0 is connected to the negative output end of the isolation power supply circuit 7. The first output end of the isolation power supply circuit 7 is connected to the input end of the gas discharge regulation circuit 3 and the input end of the gate voltage regulation circuit 4. The second output end is connected to the input end of the signal conversion circuit 5. The isolation power supply circuit 7 provides electric energy for the gas discharge regulation circuit 3, the gate voltage regulation circuit 4 and the signal conversion circuit 5. The isolation power supply circuit 7 is connected to the signal conversion circuit 5. The isolation power supply circuit 7 sends a first isolation voltage feedback electrical signal U 2f To the signal conversion circuit 5;

[0077] The signal conversion circuit 5 is connected to the main control unit 2 through the optical fiber group 8, and the signal conversion circuit 5 sends a gas discharge current feedback pulse signal I gf1 , Gas discharge voltage feedback pulse signal U gf1 , Gate voltage feedback pulse signal U bf1 , Isolation voltage feedback pulse signal U 2f1 To the main control unit 2, the main control unit 2 sends a gas discharge voltage given pulse signal U gg1 , Gate voltage given pulse signal U bg1 To the signal conversion circuit 5.

[0078] The main control unit 2 is also connected to a gas flow controller 6 for controlling the flow of the working gas input into the thermal electron gun 12 .

[0079] The main control unit 2 is also connected to the focusing coil driving circuit 10 for adjusting the current of the main focusing coil 125 of the thermal electron gun 12 .

[0080] like Figure 2 As shown, the high-voltage acceleration power supply unit 1 includes a first rectifier circuit 101, a first inverter circuit 102, a voltage doubler rectifier circuit 103, a first PWM regulation circuit 104 and a first boost transformer 105; wherein:

[0081] The output end of the first rectifier circuit 101 is connected to the input end of the first inverter circuit 102, the output end of the first inverter circuit 102 is connected to the input end of the first step-up transformer 105, the output end of the first step-up transformer 105 is connected to the input end of the voltage doubler rectifier circuit 103, the positive output end of the voltage doubler rectifier circuit 103 serves as the positive output end of the high-voltage acceleration power supply unit 1, the negative output end of the voltage doubler rectifier circuit 103 serves as the negative output end of the high-voltage acceleration power supply unit 1, and the first PWM regulation circuit 104 is connected to the first inverter circuit 102 and the DSP main control of the main control unit 2 and the first PID regulation circuit 20.

[0082] The first PWM regulation circuit 104 receives the PWM signal sent by the main control unit 2, and controls the on / off of the power switch tube in the first inverter circuit 102 according to the PWM signal;

[0083] The three-phase 380V AC power is converted into 500V DC power by the first rectifier circuit 101, and then converted into an AC square wave with an adjustable voltage of 0 to 500V and a pulse frequency of 20kHz by the first inverter circuit 102, and then converted into an AC square wave with an adjustable voltage of 0 to 10000V and a pulse frequency of 20kHz by the first step-up transformer 105, and finally rectified by the voltage doubler rectifier circuit 103 to become 0 to -150kV DC output;

[0084] The 0~-150kV DC power is connected to the negative output end of the isolation power supply circuit 7 through the current limiting resistor R0, and the 0~-150kV DC power is also connected to the first end of the voltage dividing resistor R1 and the first end of the voltage dividing resistor R2 respectively through the current limiting resistor R0; the second end of the voltage dividing resistor R1 is connected to the positive output end of the gas discharge regulation circuit 3; the second end of the voltage dividing resistor R2 is connected to the positive output end of the gate voltage regulation circuit 4.

[0085] The transformation ratio of the primary winding and the secondary winding of the first step-up transformer 105 is 1:20, and the withstand voltage level of the primary winding and the secondary winding of the first step-up transformer 105 is not less than 25 kV.

[0086] like Figure 3 As shown, the main control unit 2 includes a DSP main control and a first PID adjustment circuit 20, a first voltage / frequency and frequency / voltage signal conversion circuit 200, a first optical fiber signal receiving terminal 201, a second optical fiber signal receiving terminal 202, a third optical fiber signal receiving terminal 203, a first optical fiber signal transmitting terminal 204, a second optical fiber signal transmitting terminal 205 and a fourth optical fiber signal receiving terminal 206; wherein:

[0087] The DSP master control and the first PID adjustment circuit 20 are connected to the first pressure / frequency and frequency / pressure signal conversion circuit 200, and the first pressure / frequency and frequency / pressure signal conversion circuit 200 is connected to the output ends of the first optical fiber signal receiving terminal 201, the second optical fiber signal receiving terminal 202, the third optical fiber signal receiving terminal 203, and the fourth optical fiber signal receiving terminal 206 and the input ends of the first optical fiber signal transmitting terminal 204 and the second optical fiber signal transmitting terminal 205;

[0088] The DSP main control and the first PID adjustment circuit 20 are connected to the first PWM adjustment circuit 104 of the high-voltage acceleration power supply unit 1 and the first and second ends of the sampling resistor R5. The first voltage / frequency and frequency / voltage signal conversion circuit 200 is connected to the second PID adjustment circuit 75 of the isolation power supply circuit 7. The input ends of the first optical fiber signal receiving terminal 201, the second optical fiber signal receiving terminal 202, the third optical fiber signal receiving terminal 203, and the fourth optical fiber signal receiving terminal 206 and the output ends of the first optical fiber signal transmitting terminal 204 and the second optical fiber signal transmitting terminal 205 are respectively connected to the output ends of the third optical fiber signal transmitting terminal 501, the fourth optical fiber signal transmitting terminal 502, the fifth optical fiber signal transmitting terminal 503, and the sixth optical fiber signal transmitting terminal 506 and the input ends of the fifth optical fiber signal receiving terminal 504 and the sixth optical fiber signal receiving terminal 505 of the signal conversion circuit 5 through optical fibers.

[0089] The first voltage / frequency and frequency / voltage signal conversion circuit 200 converts the gas discharge current feedback pulse signal I received by the first optical fiber signal receiving terminal 201 into gf1 Converted into the second gas discharge current feedback electrical signal I gf2 , and sent to the DSP master control and the first PID adjustment circuit 20; the gas discharge voltage feedback pulse signal U received by the second optical fiber signal receiving terminal 202 gf1 Converted into the second gas discharge voltage feedback electrical signal U gf2 , and sent to the DSP master control and the first PID adjustment circuit 20; the gate voltage feedback pulse signal U received by the third optical fiber signal receiving terminal 203 bf1 Converted into the second gate voltage feedback electrical signal U bf2 , and sent to the DSP master control and the first PID adjustment circuit 20; the isolation voltage feedback pulse signal U received by the fourth optical fiber signal receiving terminal 206 2f1 Converted into a second isolated voltage feedback electrical signal U 2f2 , and sent to the second PID adjustment circuit 75 of the isolation power supply circuit 7;

[0090] The DSP master control and the first PID adjustment circuit 20 input a high voltage given electrical signal U from an input device such as a host computer. HVg , beam current given electrical signal U Ibg , gas discharge voltage initial electrical signal U ggw , input high voltage feedback signal U from the first end of sampling resistor R5 HV , the beam feedback electrical signal U is input from the second end of the sampling resistor R5 Ib ;

[0091] The DSP main control and the first PID adjustment circuit 20 are based on the high voltage given electrical signal U HVgAnd high voltage feedback signal U HV The PWM signal sent to the first PWM regulation circuit 104 in the high-voltage acceleration power supply unit 1 is obtained; according to the beam current given electrical signal U Ibg and the initial electrical signal U of the gas discharge voltage ggw Get the second gas discharge voltage given electrical signal U gg2 The first voltage / frequency and frequency / voltage signal conversion circuit 200 receives the second gas discharge voltage given electrical signal U output by the DSP main control and the first PID adjustment circuit 20. gg2 Converted into gas discharge voltage given pulse signal U gg1 and sent to the signal conversion circuit 5 through the second optical fiber signal transmitting terminal 205; according to the beam current given electrical signal U Ibg and beam feedback signal U Ib Get the second gate voltage given electrical signal U bg2 The first voltage / frequency and frequency / voltage signal conversion circuit 200 receives the second gate voltage given electrical signal U output by the DSP main control and the first PID adjustment circuit 20. bg2 Converted into gate voltage given pulse signal U bg1 and sent to the signal conversion circuit 5 through the first optical fiber signal transmitting terminal 204.

[0092] The DSP main control and first PID regulating circuit 20 includes both a DSP main control circuit and a PID regulating circuit of an acceleration power supply.

[0093] The DSP main control and the first PID adjustment circuit 20 can also be connected to the gas flow controller 6 and the focusing coil driving circuit 10.

[0094] like Figure 4 As shown, the isolated power supply circuit 7 includes a second rectifier circuit 71, a second inverter circuit 72, an isolation transformer 73, an isolation rectifier circuit 74, a second PID regulation circuit 75, a second PWM regulation circuit 76, a second Hall current sensor 77 and a second Hall voltage sensor 78; the isolation transformer 73 includes a primary winding 731, a first secondary winding 732 and a second secondary winding 733; wherein:

[0095] The output end of the second rectifier circuit 71 is connected to the input end of the second inverter circuit 72, the output end of the second inverter circuit 72 is connected to the input end of the isolation transformer 73, that is, the primary winding 731 of the isolation transformer, the first output end of the isolation transformer 73, that is, the first secondary winding 732 of the isolation transformer, is connected to the input end of the isolation rectifier circuit 74, the output end of the isolation rectifier circuit 74 serves as the first output end of the isolation power supply circuit 7, connected to the third inverter circuit 301 in the gas discharge regulation circuit 3 and the fourth inverter circuit 401 in the gate voltage regulation circuit 4, and the second output end of the isolation transformer 73, that is, the second secondary winding 733 of the isolation transformer, serves as the isolation power supply circuit 7. The second output end of the circuit 7 is connected to the power supply rectifier circuit 507 in the signal conversion circuit 5; the second Hall current sensor 77 collects the output current of the second inverter circuit 72 and sends it to the second PID adjustment circuit 75; the second Hall voltage sensor 78 collects the output voltage of the isolation rectifier circuit 74, that is, the first isolation voltage feedback electrical signal and sends it to the second voltage / frequency and frequency / voltage signal conversion circuit 500 in the signal conversion circuit 5; the second PID adjustment circuit 75 is connected to the second PWM adjustment circuit 76 and the DSP main control in the main control unit 2 and the first PID adjustment circuit 200, and the second PWM adjustment circuit 76 is connected to the second inverter circuit 72.

[0096] The three-phase 380V AC power is converted into 500V DC power by the second rectifier circuit 71, and then converted into an AC square wave with an amplitude voltage of 500V and a pulse frequency of 20kHz by the second inverter circuit 72, and then converted into an AC square wave with an amplitude voltage of 500V and a pulse frequency of 20kHz by the isolation transformer 73, and then converted into 500V DC power by the isolation rectifier circuit 74;

[0097] The second PID regulating circuit 75 performs PID regulation according to the second isolated voltage feedback electrical signal U2f2 sent by the first voltage / frequency and frequency / voltage signal conversion circuit 200 and the internal preset voltage given signal, and inputs the signal obtained by the regulation of the second PID regulating circuit 75 to the second PWM regulating circuit 76, and the second PWM regulating circuit 76 adjusts the PWM pulse width input to the second inverter circuit 72, and the second inverter circuit 72 adjusts the on / off time of its internal power switch to obtain an AC square wave with an amplitude voltage of 500V and a pulse frequency of 20kHz;

[0098] The current I detected by the second Hall current sensor 77 2f At the same time, it is input to the second PID regulating circuit 75 to limit the maximum power of the isolated power supply circuit 7 and protect it.

[0099] The transformation ratio of the primary winding 731 and the first secondary winding 732 of the isolation transformer 73 is 1:1, and the transformation ratio of the primary winding 731 and the second secondary winding 733 of the isolation transformer 73 is 25:1. The withstand voltage level of the primary winding 731, the first secondary winding 732 and the second secondary winding 733 is not less than 230kV.

[0100] The isolation transformer 73 is not only used to ensure the electric energy required by the gas discharge regulation circuit 3, the gate voltage regulation circuit 4, and the signal conversion circuit 5, but also can ensure the high-voltage insulation between the low-voltage circuit connected to the primary winding 731 and the circuit connected to the two secondary windings;

[0101] The isolated rectifier circuit 74 is a full-bridge rectifier circuit, which supplies power to the third inverter circuit 301 in the gas discharge regulating circuit 3 and the fourth inverter circuit 401 in the gate voltage regulating circuit 4 .

[0102] like Figure 5 As shown, the gas discharge regulation circuit 3 includes a third inverter circuit 301, a third boost transformer 302, a third rectifier circuit 303, a third Hall current sensor 304, a third Hall voltage sensor 305, a third PID regulation circuit 306 and a third PWM regulation circuit 307; wherein:

[0103] The input end of the third inverter circuit 301 is connected to the output end of the isolated rectifier circuit 74 in the isolated power supply circuit 7, the output end of the third inverter circuit 301 is connected to the input end of the third step-up transformer 302, the output end of the third step-up transformer 302 is connected to the input end of the third rectifier circuit 303, the negative output end of the third rectifier circuit 303 serves as the negative output end of the gas discharge regulation circuit 3, connected to the aluminum cathode 121 of the thermal electron gun 12, the positive output end of the third rectifier circuit 303 serves as the positive output end of the gas discharge regulation circuit 3, connected to the second end of the voltage-dividing resistor R1, and the third Hall current sensor 304 collects the current at the positive output end of the third rectifier circuit 303, i.e., the first The gas discharge current feedback electrical signal is input into the third PID regulation circuit 306 and the second voltage / frequency and frequency / voltage signal conversion circuit 500 in the signal conversion circuit 5. The third Hall voltage sensor 305 collects the output terminal voltage of the third rectifier circuit 303, i.e., the first gas discharge voltage feedback electrical signal, and inputs it into the third PID regulation circuit 306 and the second voltage / frequency and frequency / voltage signal conversion circuit 500 in the signal conversion circuit 5. The third PID regulation circuit 306 is connected to the third PWM regulation circuit 307 and the second voltage / frequency and frequency / voltage signal conversion circuit 500 in the signal conversion circuit 5. The third PWM regulation circuit 307 is connected to the third inverter circuit 301.

[0104] The third PID adjustment circuit 306 feedbacks the electrical signal I according to the first gas discharge current detected by the third Hall current sensor 304. gf , the first gas discharge voltage feedback electrical signal U detected by the third Hall voltage sensor 305 gf and the first gas discharge voltage given electrical signal U converted by the second voltage / frequency and frequency / voltage signal conversion circuit 500 in the signal conversion circuit 5 gg PID regulation is performed, and the signal obtained by the third PID regulation circuit 306 is input to the third PWM regulation circuit 307. The third PWM regulation circuit 307 adjusts the PWM pulse width input to the third inverter circuit 301. The third inverter circuit 301 adjusts the on / off time of its internal power switch, and converts the DC power from the isolated rectifier circuit 74 in the isolated power supply circuit 7 into an amplitude controllable 20kHz AC power, which is then boosted by the third boost transformer 302 and rectified by the third rectifier circuit 303 to obtain the second gas discharge voltage given electrical signal U gg2 The corresponding actual gas discharge voltage is transmitted to the aluminum cathode 121 through the negative output terminal of the third rectifier circuit 303. The second gas discharge voltage given electrical signal U gg2 Generally low, less than 10V, while the actual gas discharge voltage is several thousand volts, but the second gas discharge voltage gives the electrical signal U gg2 Corresponds one to one with the actual discharge voltage.

[0105] The transformation ratio of the primary winding and the secondary winding of the third step-up transformer 302 is 1:5, and the withstand voltage level of the primary winding and the secondary winding of the third step-up transformer 302 is not less than 5000V.

[0106] like Figure 6 As shown, the gate voltage regulation circuit 4 includes a fourth inverter circuit 401, a fourth boost transformer 402, a fourth rectifier circuit 403, a fourth Hall current sensor 404, a fourth Hall voltage sensor 405, a fourth PID regulation circuit 406 and a fourth PWM regulation circuit 407; wherein:

[0107] The input end of the fourth inverter circuit 401 is connected to the output end of the isolated rectifier circuit 74 in the isolated power supply circuit 7, the output end of the fourth inverter circuit 401 is connected to the input end of the fourth boost transformer 402, the output end of the fourth boost transformer 402 is connected to the input end of the fourth rectifier circuit 403, the negative output end of the fourth rectifier circuit 403 serves as the negative output end of the gate voltage regulating circuit 4, connected to the gate 123 of the thermal electron gun 12, the positive output end of the fourth rectifier circuit 403 serves as the positive output end of the gate voltage regulating circuit 4, connected to the second end of the voltage dividing resistor R2, and the fourth Hall current sensor 404 adopts The current at the positive output end of the fourth rectifier circuit 403 is collected and input into the fourth PID regulation circuit 406. The fourth Hall voltage sensor 405 collects the output end voltage of the fourth rectifier circuit 403, i.e., the first gate voltage feedback electrical signal, and inputs it into the fourth PID regulation circuit 406 and the second voltage / frequency and frequency / voltage signal conversion circuit 500 in the signal conversion circuit 5. The fourth PID regulation circuit 406 is connected to the fourth PWM regulation circuit 407 and the second voltage / frequency and frequency / voltage signal conversion circuit 500 in the signal conversion circuit 5. The fourth PWM regulation circuit 407 is connected to the fourth inverter circuit 401.

[0108] The fourth PID adjustment circuit 406 is based on the current I detected by the fourth Hall current sensor 404. bf , the first gate voltage feedback electrical signal U detected by the fourth Hall voltage sensor 405 bf and the first gate voltage given electrical signal U converted by the second voltage / frequency and frequency / voltage signal conversion circuit 500 in the signal conversion circuit 5 bg PID regulation is performed, and the signal obtained by the fourth PID regulation circuit 406 is input to the fourth PWM regulation circuit 407. The fourth PWM regulation circuit 407 adjusts the PWM pulse width input to the fourth inverter circuit 401. The fourth inverter circuit 401 adjusts the on / off time of its internal power switch, and converts the DC power from the isolated rectifier circuit 74 in the isolated power supply circuit 7 into an amplitude controllable 20kHz AC power, which is then boosted by the fourth boost transformer 402 and rectified by the fourth rectifier circuit 403 to obtain the second gate voltage given electrical signal U bg2 The gate voltage is consistent with the output voltage of the fourth rectifier circuit 403 and is transmitted to the gate 123 through the negative output terminal of the fourth rectifier circuit 403.

[0109] The transformation ratio of the primary winding and the secondary winding of the fourth step-up transformer 402 is 1:4, and the withstand voltage level of the primary winding and the secondary winding of the fourth step-up transformer 402 is not less than 5000V.

[0110] like Figure 7As shown, the signal conversion circuit 5 includes a second voltage / frequency and frequency / voltage signal conversion circuit 500, a third optical fiber signal transmitting terminal 501, a fourth optical fiber signal transmitting terminal 502, a fifth optical fiber signal transmitting terminal 503, a fifth optical fiber signal receiving terminal 504, a sixth optical fiber signal receiving terminal 505, a sixth optical fiber signal transmitting terminal 506, a power supply rectification circuit 507 and a DC / DC conversion circuit 508; wherein:

[0111] The input end of the power supply rectifier circuit 507 is connected to the second secondary winding 733 of the isolation transformer in the isolation power supply circuit 7, the output end of the power supply rectifier circuit 507 is connected to the input end of the DC / DC conversion circuit 508, the output end of the DC / DC conversion circuit 508 is connected to the second voltage / frequency and frequency / voltage signal conversion circuit 500, and the second voltage / frequency and frequency / voltage signal conversion circuit 500 is connected to the input ends of the third optical fiber signal transmitting terminal 501, the fourth optical fiber signal transmitting terminal 502, the fifth optical fiber signal transmitting terminal 503, and the sixth optical fiber signal transmitting terminal 506 and the output ends of the fifth optical fiber signal receiving terminal 504 and the sixth optical fiber signal receiving terminal 505;

[0112] The negative output terminal of the power supply rectifier circuit 507, the DC / DC conversion circuit 508 and the reference ground SGND of the second voltage / frequency and frequency / voltage signal conversion circuit 500 are all connected to the second end of the current limiting resistor R0 (i.e. Figure 2 and Figure 7 HV point in the figure), used to ensure that the negative output terminal of the power supply rectifier circuit 507 and the reference ground SGND of the DC / DC conversion circuit 508 are consistent with the ground potential of the gas discharge regulation circuit 3 and the gate voltage regulation circuit 4;

[0113] The power supply rectifier circuit 507 provides +20V DC power to the DC / DC conversion circuit 508, and the DC / DC conversion circuit 508 converts the +20V DC power into ±15V DC power to supply power to the second voltage / frequency and frequency / voltage signal conversion circuit 500;

[0114] The second voltage / frequency and frequency / voltage signal conversion circuit 500 is also connected to the second Hall voltage sensor 78 in the isolation power supply circuit 7, the third Hall current sensor 304, the third Hall voltage sensor 305, the third PID adjustment circuit 306 in the gas discharge adjustment circuit 3, and the fourth Hall voltage sensor 405, the fourth PID adjustment circuit 406 in the gate voltage adjustment circuit 4. The output ends of the third optical fiber signal transmitting terminal 501, the fourth optical fiber signal transmitting terminal 502, the fifth optical fiber signal transmitting terminal 503, and the sixth optical fiber signal transmitting terminal 506 and the input ends of the fifth optical fiber signal receiving terminal 504 and the sixth optical fiber signal receiving terminal 505 are respectively connected to the input ends of the first optical fiber signal receiving terminal 201, the second optical fiber signal receiving terminal 202, the third optical fiber signal receiving terminal 203, and the fourth optical fiber signal receiving terminal 206 in the main control unit and the output ends of the first optical fiber signal transmitting terminal 204 and the second optical fiber signal transmitting terminal 205 through optical fibers.

[0115] The second voltage / frequency and frequency / voltage signal conversion circuit 500 converts the first gas discharge current feedback electrical signal I collected by the third Hall current sensor 304 into gf Converted into a gas discharge current feedback pulse signal I suitable for optical fiber signal transmission gf1 , and sent to the first optical fiber signal receiving terminal 201 in the main control unit 2 through the third optical fiber signal transmitting terminal 501; the second voltage / frequency and frequency / voltage signal conversion circuit 500 converts the first gas discharge voltage feedback electrical signal U collected by the third Hall voltage sensor 305 into gf Converted into a gas discharge voltage feedback pulse signal U suitable for optical fiber signal transmission gf1 and sent to the second optical fiber signal receiving terminal 202 in the main control unit 2 through the fourth optical fiber signal transmitting terminal 502; the second voltage / frequency and frequency / voltage signal conversion circuit 500 converts the first gate voltage feedback electrical signal U collected by the fourth Hall voltage sensor 405 into bf Converted into a gate voltage feedback pulse signal U suitable for optical fiber signal transmission bf1 and sent to the third optical fiber signal receiving terminal 203 in the main control unit 2 through the fifth optical fiber signal transmitting terminal 503; the second voltage / frequency and frequency / voltage signal conversion circuit 500 converts the first isolated voltage feedback electrical signal U collected by the second Hall voltage sensor 78 into 2f Converted into an isolated voltage feedback pulse signal U suitable for optical fiber signal transmission 2f1 and sent to the fourth optical fiber signal receiving terminal 206 in the main control unit 2 through the sixth optical fiber signal transmitting terminal 506;

[0116] The second voltage / frequency and frequency / voltage signal conversion circuit 500 converts the gate voltage sent by the first optical fiber signal transmitting terminal 204 received by the fifth optical fiber signal receiving terminal 504 into a given pulse signal U bg1 Converted into the first gate voltage given electrical signal U bg , and sent to the fourth PID adjustment circuit 406; the second voltage / frequency and frequency / voltage signal conversion circuit 500 converts the gas discharge voltage given pulse signal U sent by the second optical fiber signal transmitting terminal 205 received by the sixth optical fiber signal receiving terminal 505 gg1 Converted into the first gas discharge voltage given electrical signal U gg , and sent to the third PID adjustment circuit 306.

[0117] The power supply device of the thermal electron gun also includes an oil tank, which is filled with insulating oil. The voltage doubler rectifier circuit 103, the first step-up transformer 105, the isolation transformer 73, the isolation rectifier circuit 74, the gas discharge regulation circuit 3, the gate voltage regulation circuit 4 and the signal conversion circuit 5 of the high-voltage acceleration power supply unit 1 are immersed in the insulating oil to achieve high-voltage insulation.

[0118] The power supply device of a thermal electron gun in the above-mentioned embodiment is mainly for a 150kV thermal electron gun. For a thermal electron gun of 60kV or other working voltage, it is only necessary to change the withstand voltage level of the isolation transformer 73 so that the insulation strength of the primary and secondary sides reaches more than 1.5 times of the working voltage, and change the number of stages of the voltage doubler rectifier circuit 103 so that it meets the working voltage requirement. Other circuits can remain unchanged, which greatly simplifies the design and manufacturing difficulty of the power supply device of the thermal electron gun with different working voltages.

[0119] Based on the above power supply device, the present invention also discloses a method for using the power supply device of an indirect thermal electron gun, comprising the following steps:

[0120] S1. When the vacuum degree of the vacuum chamber 11 and the thermal electron gun 12 where the workpiece 9 is located reaches the set requirements, and the water cooling pressure and the compressed air pressure are normal, the three-phase AC power is started to supply power to the power supply device, the isolated power supply circuit 7 works normally, the isolated rectifier circuit 74 outputs 500V DC, and the second voltage / frequency and frequency / voltage signal conversion circuit 500 can obtain ±15V power supply;

[0121] The main control unit 2 sets the second gate voltage to an electrical signal U bg2 Set to the maximum, and obtain the first grid voltage given electrical signal U through the first voltage / frequency and frequency / voltage signal conversion circuit 200, the optical fiber, and the second voltage / frequency and frequency / voltage signal conversion circuit 500. bg, and then transmitted to the fourth PID regulating circuit 406, so that each component in the gate voltage regulating circuit 4 works normally, and then the gate voltage connected to the negative output terminal of the gate voltage regulating circuit 4 reaches -2000V;

[0122] At the same time, the main control unit 2 energizes the main focusing coil 125 through the focusing coil driving circuit 10 according to the default value of the system setting;

[0123] S2, main control unit 2 detects whether there is a high voltage given electrical signal U from the host computer HVg , if there is a high voltage given electrical signal U HVg , then the main control unit 2 gives an electrical signal U according to the high voltage HVg , high voltage feedback signal U HV PID regulation is performed, and the regulated signal is sent to the first PWM regulation circuit 104 to control the on / off of the power switch tube in the first inverter circuit 102, so that the 500V DC obtained after rectification by the first rectifier circuit 101 is converted into an AC with an inverter frequency of 20kHz and adjustable amplitude, and then the AC is boosted by the first boost transformer 105 and rectified by the voltage doubler rectifier circuit 103 to obtain the high-voltage given electrical signal U HVg The consistent negative high voltage then enables the tungsten needle 122 connected to the negative output terminal of the voltage doubler rectifier circuit 103 through the current limiting resistor R0 to obtain the negative high voltage;

[0124] S3, the main control unit 2 detects whether there is a beam current setting electrical signal U from the host computer Ibg , if there is a beam current given electrical signal U Ibg , then jump to S5; otherwise, check whether there is an initial electrical signal U of the gas discharge voltage from the host computer ggw If not, jump to S2; otherwise, execute S4;

[0125] S4, the main control unit 2 turns on the gas flow controller 6, and introduces the working gas into the internal of the thermal electron gun 12. The main control unit 2 turns on the gas discharge voltage initial electrical signal U ggw , the second gas discharge voltage is given as an electrical signal U gg2 Assume that the initial electrical signal of the gas discharge voltage is U ggw , the second gas discharge voltage is given as an electrical signal U gg2 After passing through the first voltage / frequency and frequency / voltage signal conversion circuit 200, the optical fiber, and the second voltage / frequency and frequency / voltage signal conversion circuit 500, a new first gas discharge voltage given electrical signal U is obtained. gg , and then transmitted to the third PID regulating circuit 306, so that each component in the gas discharge regulating circuit 3 works normally, and then the voltage of the aluminum cathode 121 connected to the negative output end of the gas discharge regulating circuit 3 is equal to the second gas discharge voltage given electrical signal U gg2The corresponding actual gas discharge voltage is the same, and the second gas discharge current feedback electrical signal I is fed back to the main control unit 2. gf2 , determine the thermal emission state of the electrons emitted by the tungsten needle 122, and jump to S8;

[0126] S5, the main control unit 2 turns on the gas flow controller 6, and introduces the working gas into the internal of the thermal electron gun 12. At the same time, the main control unit 2 gives the system default second gas discharge voltage given electrical signal U gg2 , a new first gas discharge voltage given electrical signal U is obtained through the first voltage / frequency and frequency / voltage signal conversion circuit 200, the optical fiber, and the second voltage / frequency and frequency / voltage signal conversion circuit 500. gg , and then transmitted to the third PID regulating circuit 306, so that each component in the gas discharge regulating circuit 3 works normally, and then the voltage of the aluminum cathode 121 connected to the negative output end of the gas discharge regulating circuit 3 is equal to the second gas discharge voltage given electrical signal U gg2 The corresponding actual gas discharge voltage is the same;

[0127] There is a negative voltage of several thousand volts between the aluminum cathode 121 and the tungsten needle 122, which can cause the working gas between the aluminum cathode 121 and the tungsten needle 122 to discharge and form plasma. The positive ions in the plasma bombard the surface of the aluminum cathode 121, and stimulate secondary electrons to bombard the tungsten needle 122. The secondary electrons convert kinetic energy into thermal energy, heating the tungsten needle 122 to a thermal emission state where it can emit electrons.

[0128] The thermal emission state of the tungsten needle 122 emitting electrons can be fed back by the first gas discharge current to form an electrical signal I gf The first gas discharge current feedback electrical signal I gf After passing through the second voltage / frequency and frequency / voltage signal conversion circuit 500, the optical fiber, and the first voltage / frequency and frequency / voltage signal conversion circuit 200, a second gas discharge current feedback electrical signal I is obtained. gf2 The data table of the corresponding relationship between the gas flow rate, the gas discharge voltage, the gas discharge current and the beam current is stored in the memory of the DSP main control and the first PID adjustment circuit 20. After looking up the table, the gas flow rate set value can be obtained. The main control unit 2 resets the gas flow rate of the gas flow controller so that the first gas discharge current feedback electrical signal I gf Reach the set state.

[0129] S6, the main control unit 2 gives an electrical signal U according to the beam current Ibg , beam feedback electrical signal U IbPID regulation is performed, and the signal after PID regulation passes through the first voltage / frequency and frequency / voltage signal conversion circuit 200, the optical fiber, and the second voltage / frequency and frequency / voltage signal conversion circuit 500 to obtain a new first grid voltage given electrical signal U bg , and then transmitted to the fourth PID adjustment circuit 406, so that each component in the grid voltage adjustment circuit 4 works normally, and then adjusts the grid voltage so that the beam current feedback electrical signal U at the first end of the beam current sampling resistor R3 Ib With the beam current given electrical signal U Ibg be consistent;

[0130] S7, check whether there is a stop signal from the host computer. If no stop signal is detected, jump to S2; otherwise jump to S9;

[0131] S8, detect whether there is a gas discharge voltage initial electrical signal U from the host computer ggw , if yes, jump to S4, otherwise jump to S2;

[0132] S9, the main control unit 2 will not consider the high voltage given electrical signal U HVg , directly set the signal sent to the first PWM regulation circuit 104 to zero, so that the output of the high-voltage acceleration power supply unit 1 is zero, and the second gas discharge voltage is given as the electrical signal U gg2 and the second gate voltage given electrical signal U bg2 Set it to 0, so that the output of the gas discharge regulating circuit 3 and the grid voltage regulating circuit 4 is zero, turn off the gas flow controller 6, the focusing coil driving circuit 10, etc., and then turn off the three-phase AC power.

[0133] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A power supply device for an indirect thermal electron gun, It is characterized in that It comprises a high-voltage acceleration power supply unit (1), a main control unit (2), a gas discharge regulation circuit (3), a grid voltage regulation circuit (4), a signal conversion circuit (5), an isolation power supply circuit (7) and an optical fiber group (8), wherein: The positive output end of the high-voltage acceleration power supply unit (1) is connected to the first end of the beam sampling resistor R3, and the second end of the beam sampling resistor R3 is grounded and connected to the vacuum chamber (11); The negative output end of the high-voltage acceleration power supply unit (1) is connected to the first end of the current limiting resistor R0, the second end of the current limiting resistor R0 is connected to the tungsten needle (122), the second end of the current limiting resistor R0 is connected to the first end of the voltage dividing resistor R4, the second end of the voltage dividing resistor R4 is connected to the first end of the sampling resistor R5, the second end of the sampling resistor R5 is connected to the positive output end of the high-voltage acceleration power supply unit (1), the first end and the second end of the sampling resistor R5 are both connected to the main control unit (2), and the main control unit (2) is also connected to the high-voltage acceleration power supply unit (1) and the isolation power supply circuit (7); The second end of the current limiting resistor R0 is connected to the first end of the voltage dividing resistor R1, the second end of the voltage dividing resistor R1 is connected to the positive output end of the gas discharge regulating circuit (3), the negative output end of the gas discharge regulating circuit (3) is connected to the aluminum cathode (121), and the gas discharge regulating circuit (3) is connected to the signal conversion circuit (5); The second end of the current limiting resistor R0 is connected to the first end of the voltage dividing resistor R2, the second end of the voltage dividing resistor R2 is connected to the positive output end of the gate voltage regulating circuit (4), the negative output end of the gate voltage regulating circuit (4) is connected to the gate (123), and the gate voltage regulating circuit (4) is connected to the signal conversion circuit (5); The second end of the current limiting resistor R0 is connected to the negative output end of the isolation power supply circuit (7), the first output end of the isolation power supply circuit (7) is connected to the gas discharge regulation circuit (3) and the gate voltage regulation circuit (4), and the second output end of the isolation power supply circuit (7) is connected to the signal conversion circuit (5); The signal conversion circuit (5) is connected to the main control unit (2) via an optical fiber group (8).

2. A power supply device for an indirect thermal electron gun according to claim 1, It is characterized in that The high-voltage acceleration power supply unit (1) comprises a first rectifier circuit (101), a first inverter circuit (102), a voltage doubling rectifier circuit (103), a first PWM regulation circuit (104) and a first step-up transformer (105); wherein: The input end of the first rectifier circuit (101) is connected to a three-phase 380V alternating current, the output end of the first rectifier circuit (101) is connected to the input end of the first inverter circuit (102), the output end of the first inverter circuit (102) is connected to the input end of the first step-up transformer (105), the output end of the first step-up transformer (105) is connected to the input end of the voltage-doubling rectifier circuit (103), the positive output end of the voltage-doubling rectifier circuit (103) serves as the positive output end of the high-voltage acceleration power supply unit (1), the negative output end of the voltage-doubling rectifier circuit (103) serves as the negative output end of the high-voltage acceleration power supply unit (1), and the first PWM regulation circuit (104) is connected to the first inverter circuit (102) and the main control unit (2).

3. A power supply device for an indirect thermal electron gun according to claim 2, It is characterized in that The main control unit (2) comprises a DSP main control and a first PID adjustment circuit (20), a first voltage / frequency and frequency / voltage signal conversion circuit (200), a first optical fiber signal receiving terminal (201), a second optical fiber signal receiving terminal (202), a third optical fiber signal receiving terminal (203), a first optical fiber signal transmitting terminal (204), a second optical fiber signal transmitting terminal (205) and a fourth optical fiber signal receiving terminal (206); wherein: The DSP main control and the first PID adjustment circuit (20) are connected to the first pressure / frequency and frequency / pressure signal conversion circuit (200); the first pressure / frequency and frequency / pressure signal conversion circuit (200) is connected to the output ends of the first optical fiber signal receiving terminal (201), the second optical fiber signal receiving terminal (202), the third optical fiber signal receiving terminal (203), and the fourth optical fiber signal receiving terminal (206) and the input ends of the first optical fiber signal transmitting terminal (204) and the second optical fiber signal transmitting terminal (205); The DSP main control and the first PID adjustment circuit (20) are connected to a high-voltage acceleration power supply unit (1) and the first end and the second end of a sampling resistor R5; the first voltage / frequency and frequency / voltage signal conversion circuit (200) is connected to an isolation power supply circuit (7); the input ends of the first optical fiber signal receiving terminal (201), the second optical fiber signal receiving terminal (202), the third optical fiber signal receiving terminal (203), and the fourth optical fiber signal receiving terminal (206) and the output ends of the first optical fiber signal transmitting terminal (204) and the second optical fiber signal transmitting terminal (205) are respectively connected to the signal conversion circuit (5) via optical fibers.

4. A power supply device for an indirect thermal electron gun according to claim 3, It is characterized in that The isolated power supply circuit (7) comprises a second rectifier circuit (71), a second inverter circuit (72), an isolation transformer (73), an isolation rectifier circuit (74), a second PID regulation circuit (75), a second PWM regulation circuit (76), a second Hall current sensor (77), and a second Hall voltage sensor (78); the isolation transformer (73) comprises a primary winding (731), a first secondary winding (732), and a second secondary winding (733); wherein: The input end of the second rectifier circuit (71) is connected to a three-phase 380V alternating current, the output end of the second rectifier circuit (71) is connected to the input end of the second inverter circuit (72), the output end of the second inverter circuit (72) is connected to the primary winding (731) of the isolation transformer, the first secondary winding (732) of the isolation transformer is connected to the input end of the isolation rectifier circuit (74), the output end of the isolation rectifier circuit (74) serves as the first output end of the isolation power supply circuit (7), and the second secondary winding (733) of the isolation transformer serves as the second output end of the isolation power supply circuit (7); the second Hall current sensor (77) collects the output current of the second inverter circuit (72) and sends it to the second PID regulation circuit (75); the second Hall voltage sensor (78) collects the output voltage of the isolation rectifier circuit (74), i.e., the first isolation voltage feedback electrical signal, and sends it to the signal conversion circuit (5); the second PID regulation circuit (75) is connected to the second PWM regulation circuit (76) and the main control unit (2), and the second PWM regulation circuit (76) is connected to the second inverter circuit (72).

5. A power supply device for an indirect thermal electron gun according to claim 4, It is characterized in that The gas discharge regulation circuit (3) comprises a third inverter circuit (301), a third step-up transformer (302), a third rectifier circuit (303), a third Hall current sensor (304), a third Hall voltage sensor (305), a third PID regulation circuit (306) and a third PWM regulation circuit (307); wherein: The input end of the third inverter circuit (301) is connected to the first output end of the isolation power supply circuit (7), the output end of the third inverter circuit (301) is connected to the input end of the third step-up transformer (302), the output end of the third step-up transformer (302) is connected to the input end of the third rectifier circuit (303), the negative output end of the third rectifier circuit (303) serves as the negative output end of the gas discharge regulation circuit (3), the positive output end of the third rectifier circuit (303) serves as the positive output end of the gas discharge regulation circuit (3), and the third Hall current sensor (304) collects the output of the third rectifier circuit (303). ), the current at the positive output end of the third rectifier circuit (303), i.e., the first gas discharge current feedback electrical signal, is input into the third PID regulation circuit (306) and the signal conversion circuit (5); the third Hall voltage sensor (305) collects the output end voltage of the third rectifier circuit (303), i.e., the first gas discharge voltage feedback electrical signal, and inputs it into the third PID regulation circuit (306) and the signal conversion circuit (5); the third PID regulation circuit (306) is connected to the third PWM regulation circuit (307) and the signal conversion circuit (5); and the third PWM regulation circuit (307) is connected to the third inverter circuit (301).

6. A power supply device for an indirect thermal electron gun according to claim 5, It is characterized in that The gate voltage regulation circuit (4) comprises a fourth inverter circuit (401), a fourth step-up transformer (402), a fourth rectifier circuit (403), a fourth Hall current sensor (404), a fourth Hall voltage sensor (405), a fourth PID regulation circuit (406) and a fourth PWM regulation circuit (407); wherein: The input end of the fourth inverter circuit (401) is connected to the first output end of the isolation power supply circuit (7), the output end of the fourth inverter circuit (401) is connected to the input end of the fourth step-up transformer (402), the output end of the fourth step-up transformer (402) is connected to the input end of the fourth rectifier circuit (403), the negative output end of the fourth rectifier circuit (403) serves as the negative output end of the gate voltage regulation circuit (4), the positive output end of the fourth rectifier circuit (403) serves as the positive output end of the gate voltage regulation circuit (4), and the fourth Hall current sensor (404) serves as the output end of the fourth Hall current sensor (404). ) collects the current at the positive output end of the fourth rectifier circuit (403) and inputs it into the fourth PID regulation circuit (406); the fourth Hall voltage sensor (405) collects the output end voltage of the fourth rectifier circuit (403), i.e., the first gate voltage feedback electrical signal, and inputs it into the fourth PID regulation circuit (406) and the signal conversion circuit (5); the fourth PID regulation circuit (406) is connected to the fourth PWM regulation circuit (407) and the signal conversion circuit (5); and the fourth PWM regulation circuit (407) is connected to the fourth inverter circuit (401).

7. A power supply device for an indirect thermal electron gun according to claim 6, It is characterized in that The signal conversion circuit (5) comprises a second voltage / frequency and frequency / voltage signal conversion circuit (500), a third optical fiber signal transmitting terminal (501), a fourth optical fiber signal transmitting terminal (502), a fifth optical fiber signal transmitting terminal (503), a fifth optical fiber signal receiving terminal (504), a sixth optical fiber signal receiving terminal (505), a sixth optical fiber signal transmitting terminal (506), a power supply rectification circuit (507) and a DC / DC conversion circuit (508); wherein: The input end of the power supply rectifier circuit (507) is connected to the second output end of the isolation power supply circuit (7), the output end of the power supply rectifier circuit (507) is connected to the input end of the DC / DC conversion circuit (508), the output end of the DC / DC conversion circuit (508) is connected to the second voltage / frequency and frequency / voltage signal conversion circuit (500), and the second voltage / frequency and frequency / voltage signal conversion circuit (500) is connected to the input ends of the third optical fiber signal transmitting terminal (501), the fourth optical fiber signal transmitting terminal (502), the fifth optical fiber signal transmitting terminal (503), and the sixth optical fiber signal transmitting terminal (506), and the output ends of the fifth optical fiber signal receiving terminal (504) and the sixth optical fiber signal receiving terminal (505); The negative output end of the power supply rectifier circuit (507), the DC / DC conversion circuit (508) and the reference ground of the second voltage / frequency and frequency / voltage signal conversion circuit (500) are all connected to the second end of the current limiting resistor R0; the second voltage / frequency and frequency / voltage signal conversion circuit (500) is also connected to the isolation power supply circuit (7), the gas discharge regulation circuit (3) and the gate voltage regulation circuit (4); the output ends of the third optical fiber signal transmitting terminal (501), the fourth optical fiber signal transmitting terminal (502), the fifth optical fiber signal transmitting terminal (503) and the sixth optical fiber signal transmitting terminal (506) and the input ends of the fifth optical fiber signal receiving terminal (504) and the sixth optical fiber signal receiving terminal (505) are respectively connected to the main control unit (2) via optical fibers.

8. A power supply device for an indirect thermal electron gun according to claim 7, It is characterized in that The invention also comprises an oil tank, wherein the oil tank is filled with insulating oil, and the voltage doubling rectifier circuit (103) of the high-voltage acceleration power supply unit (1), the first step-up transformer (105), the isolation transformer (73) of the isolation power supply circuit (7), the isolation rectifier circuit (74), the gas discharge regulating circuit (3), the gate voltage regulating circuit (4), and the signal conversion circuit (5) are immersed in the insulating oil.

9. A power supply device for an indirect thermal electron gun according to claim 1, It is characterized in that The main control unit (2) is also connected to a gas flow controller (6) and a focusing coil driving circuit (10).

10. A method for using a power supply device of an indirect thermal electron gun, It is characterized in that The steps include: S1. When the vacuum degree of the vacuum chamber (11) where the workpiece (9) is located and the thermal electron gun (12) reaches the set requirements, and the water cooling pressure and the compressed air pressure reach the set requirements, the three-phase AC power is started to supply power to the power supply device, the isolated power supply circuit (7) works normally, the isolated rectifier circuit (74) outputs 500V DC, and the second voltage / frequency and frequency / voltage signal conversion circuit (500) obtains ±15V power supply; The main control unit (2) sets the second gate voltage to an electrical signal U bg2 The first grid voltage given electrical signal U is obtained after being set to the maximum through the first voltage / frequency and frequency / voltage signal conversion circuit (200), the optical fiber, and the second voltage / frequency and frequency / voltage signal conversion circuit (500). bg , and then transmitted to the fourth PID regulating circuit (406), so that each component in the gate voltage regulating circuit (4) works normally, and then the gate voltage connected to the negative output terminal of the gate voltage regulating circuit (4) reaches -2000V; At the same time, the main control unit (2) energizes the main focusing coil (125) through the focusing coil driving circuit (10) according to the default value of the system setting; S2, the main control unit (2) detects whether there is a high-voltage given electrical signal U from the host computer HVg , if there is a high voltage given electrical signal U HVg , then the main control unit (2) generates a high voltage given electrical signal U HVg , the high voltage feedback electrical signal U at the first end of the sampling resistor R5 HV PID regulation is performed, and the regulated signal is sent to the first PWM regulation circuit (104) to control the on / off of the power switch tube in the first inverter circuit (102), so that the 500V direct current obtained after rectification by the first rectifier circuit (101) is converted into alternating current with an inverter frequency of 20kHz and adjustable amplitude, and then the alternating current is stepped up by the first step-up transformer (105) and rectified by the voltage doubling rectifier circuit (103) to obtain an alternating current with the same voltage as the high-voltage given electrical signal U HVg The corresponding negative high voltage then enables the tungsten needle (122) connected to the negative output end of the voltage doubler rectifier circuit (103) through the current limiting resistor R0 to obtain the negative high voltage; S3, the main control unit (2) detects whether there is a beam current setting electrical signal U from the host computer Ibg , if there is a beam current given electrical signal U Ibg , then jump to S5; otherwise, check whether there is an initial electrical signal U of the gas discharge voltage from the host computer ggw If not, jump to S2; otherwise, execute S4; S4, the main control unit (2) turns on the gas flow controller (6) to introduce working gas into the internal part of the thermal electron gun (12), and the main control unit (2) generates a gas discharge voltage initial electrical signal U ggw , the second gas discharge voltage is given as an electrical signal U gg2 Assume that the initial electrical signal of the gas discharge voltage is U ggw , the second gas discharge voltage is given as an electrical signal U gg2 After passing through the first voltage / frequency and frequency / voltage signal conversion circuit (200), the optical fiber, and the second voltage / frequency and frequency / voltage signal conversion circuit (500), a new first gas discharge voltage given electrical signal U is obtained. gg , and then transmitted to the third PID regulating circuit (306), so that each component in the gas discharge regulating circuit (3) works normally, and then the voltage of the aluminum cathode (121) connected to the negative output end of the gas discharge regulating circuit (3) is equal to the second gas discharge voltage given electrical signal U gg2 The corresponding actual gas discharge voltage is the same, and according to the second gas discharge current feedback electrical signal I fed back to the main control unit (2) gf2 , judging the thermal emission state of the electrons emitted by the tungsten needle (122), and jumping to S8; S5, the main control unit (2) turns on the gas flow controller (6) to introduce working gas into the internal part of the thermal electron gun (12), and at the same time the main control unit (2) gives the system default second gas discharge voltage given electrical signal U gg2 , a new first gas discharge voltage given electrical signal U is obtained through a first voltage / frequency and frequency / voltage signal conversion circuit (200), an optical fiber, and a second voltage / frequency and frequency / voltage signal conversion circuit (500). gg , and then transmitted to the third PID regulating circuit (306), so that each component in the gas discharge regulating circuit (3) works normally, and then the voltage of the aluminum cathode (121) connected to the negative output end of the gas discharge regulating circuit (3) is equal to the second gas discharge voltage given electrical signal U gg2 The corresponding actual gas discharge voltage is the same; There is a negative voltage of several thousand volts between the aluminum cathode (121) and the tungsten needle (122), so that the working gas between the aluminum cathode (121) and the tungsten needle (122) discharges to form plasma, and the positive ions in the plasma bombard the surface of the aluminum cathode (121), and stimulate secondary electrons to bombard the tungsten needle (122), and the secondary electrons convert kinetic energy into thermal energy, so that the tungsten needle (122) is heated to a thermal emission state of emitting electrons; The thermal emission state of the tungsten needle (122) emitting electrons is fed back to the electric signal I via the first gas discharge current. gf The first gas discharge current feedback electrical signal I gf After passing through the second voltage / frequency and frequency / voltage signal conversion circuit (500), the optical fiber, and the first voltage / frequency and frequency / voltage signal conversion circuit (200), a second gas discharge current feedback electrical signal I is obtained. gf2 The data is input to the DSP main control and the first PID regulating circuit (20). The memory of the DSP main control and the first PID regulating circuit (20) stores a data table of a series of corresponding relationships among gas flow, gas discharge voltage, gas discharge current and beam current size. After looking up the table, a given value of the gas flow is obtained. The main control unit (2) resets the gas flow size of the gas flow controller (6) so that the first gas discharge current feedback electrical signal I gf Reaching a set state; S6, the main control unit (2) gives an electrical signal U according to the beam current Ibg , beam feedback electrical signal U Ib PID regulation is performed, and the signal after PID regulation passes through the first voltage / frequency and frequency / voltage signal conversion circuit (200), the optical fiber, and the second voltage / frequency and frequency / voltage signal conversion circuit (500) to obtain a new first grid voltage given electrical signal U bg , and then transmitted to the fourth PID adjustment circuit (406), so that each component in the grid voltage adjustment circuit (4) works normally, and then adjusts the grid voltage so that the beam current feedback electrical signal U at the first end of the beam current sampling resistor R3 Ib With the beam current given electrical signal U Ibg be consistent; S7, check whether there is a stop signal from the host computer. If no stop signal is detected, jump to S2; otherwise, if a stop signal is detected, jump to S9; S8, detect whether there is a gas discharge voltage initial electrical signal U from the host computer ggw , if yes, jump to S4, otherwise jump to S2; S9, the main control unit (2) will not consider the high voltage given electrical signal U HVg , directly setting the signal sent to the first PWM regulation circuit (104) to zero, making the output of the high-voltage acceleration power supply unit (1) zero, and setting the second gas discharge voltage given electrical signal U gg2 and the second gate voltage given electrical signal U bg2 Set to 0, so that the output of the gas discharge regulating circuit (3) and the grid voltage regulating circuit (4) is zero, the gas flow controller (6) and the focusing coil driving circuit (10) are turned off, and then the three-phase alternating current is turned off.

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