High-voltage power supply for driving plasma, microwave source and microwave heating system

Abstract

The embodiment of the invention provides a high-voltage power supply for driving plasma, a microwave source and a microwave heating system.The high-voltage power supply comprises a Marx generator which is provided with N stages of Marx modules and used for outputting high-voltage pulses, and each Marx module comprises an energy storage capacitor, an all-solid-state switch and a driving module, the driving module supplies power through an energy storage capacitor in the Marx module and is used for driving the all-solid-state switch, and N is a positive integer greater than 1; the charging circuit is used for charging the energy storage capacitor; and the control system is used for controlling the charge and discharge process of the Marx generator. A Marx generator is adopted as a high-voltage power supply of the microwave source for carrying out auxiliary heating on plasmas of thermonuclear fusion, so that high on-off speed can be realized, a multi-path driving power supply for isolated power supply does not need to be provided, and negative high-voltage pulses required by the microwave source can be safely output; and the output power of the microwave source can meet higher transient power and time scale required by thermonuclear fusion.

Description

Technical Field

[0001] The present application relates to the field of electronic power technology, and in particular to a high voltage power supply, a microwave source and a microwave heating system for driving plasma. Background Art

[0002] In thermonuclear fusion technology, it is usually necessary to heat the plasma to a sufficiently high reaction temperature. The traditional heating method is ohmic heating, but during the ohmic heating process, as the plasma temperature increases, the resistivity of the plasma becomes smaller and smaller, so the heating efficiency becomes smaller and smaller. The temperature of the reactor cannot be reached by using only ohmic heating, and auxiliary heating must be used. Common auxiliary heating methods mainly include two categories: high-energy neutral particle beam heating and radio frequency heating. Among them, according to the different radio frequency bands selected, radio frequency heating has three types: ion cyclotron resonance heating, low hybrid wave resonance heating and electron cyclotron resonance heating. Small magnetic confinement devices (for example, the SUNIST tokamak device, whose toroidal magnetic field is about 0.1T) usually use electron cyclotron resonance heating, and the corresponding microwave source usually uses 2.45GHz.

[0003] However, the maximum power of the commonly used magnetron-based 2.45GHz microwave source in the relevant technology is only 15kW, which cannot meet the higher transient power requirements (above 30kW) of the SUNIST tokamak device. In addition, the on-off time of this type of microwave source is in the second level, while the discharge window of the SUNIST tokamak device is in the millisecond level, making it impossible for existing microwave sources to achieve precise time control during the discharge process of the tokamak device.

[0004] Therefore, how to make the microwave source better meet the higher transient power and time scale of thermonuclear fusion has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] The present application provides a high-voltage power supply, a microwave source and a microwave heating system for driving plasma, which at least solves the technical problem existing in the related art of how to enable the microwave source to better meet the higher transient power and time scale of thermonuclear fusion.

[0006] An embodiment of the present application provides a high-voltage power supply for driving plasma, including: a Max generator having N levels of Max modules for outputting high-voltage pulses, the Max modules including energy storage capacitors, all-solid-state switches and driving modules, the driving module being powered by the energy storage capacitors in the current-level Max modules for driving the all-solid-state switches, wherein N is a positive integer greater than 1; a charging circuit connected to the Max generator for charging the energy storage capacitors; and a control system connected to the Max generator for controlling the charging and discharging process of the Max generator.

[0007] In one embodiment, the Max module further includes a driving power supply circuit, an input end of which is connected to the energy storage capacitor, and an output end of which is connected to the driving module, for converting the voltage of the energy storage capacitor into a power supply voltage of the driving module.

[0008] In one embodiment, the reference potential terminal of the all-solid-state switch is connected to the negative electrode of the energy storage capacitor and is at the same potential.

[0009] In one embodiment, the Max module further includes: a first diode and a second diode, the all-solid-state switch includes an IGBT; the cathode of the first diode is connected to the anode of the energy storage capacitor, the anode of the first diode is connected to the collector of the IGBT and to the positive input terminal of the Max module; the cathode of the second diode is connected to the emitter of the IGBT, the anode of the first diode is connected to the negative output terminal of the Max module, and the emitter of the IGBT is connected to the cathode of the energy storage capacitor.

[0010] In one embodiment, the control system includes: a controller connected to the drive circuit via a signal isolation circuit, and configured to output a trigger signal to the drive circuit; and a monitoring module, configured to collect a status signal of the Max module and transmit the signal to the controller.

[0011] In one embodiment, the charging circuit includes a DC charging power supply and a charging control switch, wherein the control end of the charging control switch is connected to the control system, is closed when triggered by a charging instruction output by the control system to turn on the charging circuit, and is disconnected when triggered by a stop charging instruction output by the control system to disconnect the charging circuit.

[0012] According to the second aspect, an embodiment of the present application provides a microwave source, comprising: a microwave generator and a microwave transmission line; the microwave generator comprises a cathode for providing thermal electrons; and a high-voltage power supply as described in the first aspect above, for applying an electric field to drive electron movement to generate microwave oscillations of thermal electrons; the microwave transmission line and the output end of the microwave generator are used to output the microwave oscillations.

[0013] In one embodiment, the microwave source also includes: a cathode power supply for providing a continuous steady-state current to the cathode, the power supply including an isolation transformer, a rectifier circuit and a filter circuit; the cathode includes a cooling device for cooling the rectifier circuit, the filter circuit and the cathode.

[0014] In one embodiment, the microwave transmission line includes: an excitation cavity, a circulator, a DC isolator, a ceramic window, an antenna, and a water load connected to the circulator, which are connected in sequence; a directional coupler is connected at at least one of the locations between the excitation cavity and the circulator, between the DC isolator and the ceramic window, and between the circulator and the water load.

[0015] According to a third aspect, an embodiment of the present application provides a microwave heating system, comprising: a microwave source as described in any one of the second aspects above, coupled to the plasma of a thermonuclear reaction device to heat the plasma.

[0016] The present application has at least the following beneficial effects:

[0017] The high-voltage power supply of the microwave source used for auxiliary heating of the plasma of thermonuclear fusion adopts a Max generator, in which the all-solid-state switch can achieve a high-speed on-off speed. By adjusting the trigger signal of the solid-state switch, the stable discharge platform period matching the stable platform period of the plasma can be accurately achieved. The energy storage capacitor in the Max module of this level is used to self-power the driving module of the all-solid-state switch. There is no need to isolate the all-solid-state switches in the Max modules of each level. Therefore, there is no need to design a complex power supply circuit, and the structure is simpler. Moreover, the use of energy storage capacitors to self-power the driving module of the all-solid-state switch can continuously provide continuous quasi-steady-state power supply. In addition, in the present application, since the energy storage capacitor is used to self-power the driving module, the driving module can continuously consume the energy of the energy storage capacitor, and the energy of the energy storage capacitor is reduced to a safe level. High voltage exists during working, and high voltage does not exist during non-working, thereby achieving passive safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0020] Figure 1 A schematic diagram of an exemplary high voltage power supply for driving plasma according to an embodiment of the present application;

[0021] Figure 2 A schematic diagram of an exemplary Max module in an embodiment of the present application;

[0022] Figure 3A schematic diagram of an exemplary Max generator according to an embodiment of the present application;

[0023] Figure 4 This is a schematic diagram of an exemplary high-voltage power supply charging state according to an embodiment of the present application;

[0024] Figure 5 This is a schematic diagram of an exemplary high-voltage power supply discharge state according to an embodiment of the present application;

[0025] Figure 6 Another exemplary high-voltage power supply modular schematic diagram of an embodiment of the present application;

[0026] Figure 7 A schematic diagram of a microwave generator in a microwave source according to an embodiment of the present application;

[0027] Figure 8 A schematic diagram of a microwave transmission line in a microwave source according to an embodiment of the present application;

[0028] Fig. 9 A waveform diagram of the microwave source output according to an embodiment of the present application;

[0029] Fig.10 Schematic diagram of waveforms of microwave source output power scanning and detector measurement according to an embodiment of the present application. DETAILED DESCRIPTION

[0030] In order to enable ordinary technicians in this field to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of this application.

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] Referring to the description of the background technology, a stable microwave source is required when electron cyclotron resonance is used to assist in heating the plasma of the tokamak device. Microwave power essentially comes from the drift motion of electrons, so its output power is more sensitive to high-voltage input, so a high-voltage pulse power supply is required to be able to discharge stably; and the plasma duration of the SUNIST tokamak device is about 20ms, and the stable plateau period is about 10ms. Therefore, the high-voltage pulse power supply should have a high-speed opening and closing capability to match the duration of the plasma or the stable plateau period. The high-voltage power supply in the prior art often uses twelve-pulse rectification, not only the transient output power cannot meet the higher transient power of the SUNIST tokamak device, but also the time scale of its opening and closing is usually in the order of seconds, making it difficult to achieve precise time control.

[0033] Some other pulsed high-voltage power supplies, such as all-solid-state Max generators, have high-speed opening and closing capabilities. However, the all-solid-state switches in the all-solid-state Max generators are not at the same potential, and their power supply needs to solve the problems of high and low potential isolation and mutual isolation of various power supplies. Usually, the design of steady-state isolated power supply is difficult. In order to reduce the isolation difficulty between the power supplies of the all-solid-state switch, the power supply and triggering of its driving circuit often use the same circuit, and the power supply and triggering use the same circuit can only provide transient power supply, so that the pulse width of the high-voltage pulse of the Max generator in the prior art is often transient, usually at the nanosecond level or microsecond level. The plateau period of the plasma duration of the present application is about 10ms. Therefore, the high-voltage power supply is required to have a steady-state output or quasi-steady-state output at the millisecond level in the present application. For example, the high-voltage power supply is required to output a high-voltage pulse with a quasi-steady-state pulse width of 5-10ms. The all-solid-state Max generator in the prior art is often difficult to meet the demand for high-voltage power supply of the microwave source for heating the plasma of the SUNIST Tokamak device of the present application.

[0034] Based on this, this embodiment provides a high-voltage power supply for driving plasma, which can be used to provide negative high voltage for a microwave source to drive the drift motion of electrons, thereby generating microwave vibrations for heating the plasma of the SUNIST Tokamak device.

[0035] like Figure 1As shown, the high-voltage power supply includes: a Max generator 110, having N-level Max modules 111, for outputting high-voltage pulses, wherein the Max module 111 includes an energy storage capacitor 1111, a full-solid-state switch 1112 and a driving module 1113, wherein the driving module 1113 is powered by the energy storage capacitor 1111 of the Max module at this level, and is used to trigger the full-solid-state switch 1112 to turn on and off, wherein N is a positive integer greater than 1; a charging circuit 120, connected to the Max generator 110, for charging the energy storage capacitor 1111; and a control system 130, connected to the Max generator 110, for controlling the charging and discharging process of the Max generator 110.

[0036] In the present application, a high-voltage power supply of a microwave source for auxiliary heating of thermonuclear fusion plasma adopts a Max generator, in which an all-solid-state switch can achieve a high-speed on-off speed. By adjusting the trigger signal of the solid-state switch, a stable discharge platform period matching the stable platform period of the plasma can be accurately achieved. The energy storage capacitor in the Max module of this level is used to self-power the driving module of the all-solid-state switch. There is no need to isolate the all-solid-state switches in the Max modules of each level. Therefore, there is no need to design a complex power supply circuit, and the structure is simpler. Moreover, the use of an energy storage capacitor to self-power the driving module of the all-solid-state switch can continuously provide continuous quasi-steady-state power supply. In addition, in the present application, since the energy storage capacitor is used to self-power the driving module, the driving module can continuously consume the energy of the energy storage capacitor, and the energy of the energy storage capacitor is reduced to a safe level. High voltage exists during working, and high voltage does not exist during non-working, thereby achieving passive safety.

[0037] In this embodiment, the all-solid-state switch 1112 uses a fully controlled device, such as a GTR, an IGBT, a MOSFET, a Darlington tube, etc. In this embodiment, IGBT can be used as an example for explanation. In this embodiment, the energy storage capacitor 1111 can use an electrolytic capacitor. For example, a 400V / 10mF electrolytic capacitor can be used. The working voltage of a single Max module 111 is 400V. Of course, other electrolytic capacitors can also be used. The specific voltage and capacitance of the electrolytic capacitor can be selected based on the requirements of the microwave source.

[0038] As an exemplary embodiment, the reference potential terminal of the all-solid-state switch is connected to the negative electrode of the energy storage capacitor and is at the same potential. One end of the all-solid-state switch is connected to a high potential, and the other end is connected to a low potential. The low potential end is usually used as the reference potential end, for example, a grounded end or an end connected to a certain potential in the circuit. In this embodiment, the reference potential end is connected to the negative electrode of the energy storage capacitor and is connected to the same potential in the circuit, for example, grounded. Figure 2 and 3As shown, taking IGBT as an example, the emitter of IGBT is directly connected to the negative electrode of the energy storage capacitor in this stage through a wire. When the energy storage capacitor in this stage supplies power to the driving module of the IGBT in this stage, all potentials in this stage can be at the same level, thereby achieving more stable voltage detection and current protection, and preventing false triggering or damage to devices caused by inconsistent potentials. If other types of solid-state switches are used, their reference potential end is directly connected to the negative electrode of the energy storage capacitor.

[0039] When the Max generator 110 needs to be charged, the control system 130 controls the all-solid-state switch 1112 to be disconnected, the energy storage capacitors 1111 in each level of the Max modules 111 are in parallel, and the charging circuit 120 is controlled to charge the energy storage capacitors 1111. When discharging, the control system 130 controls the all-solid-state switches 1112 in the corresponding number of Max modules 111 to be closed based on the voltage requirement of the microwave source, and the energy storage capacitors 1111 in multiple Max modules 111 are connected in series to output the corresponding voltage.

[0040] As an exemplary embodiment, taking a 450V / 10mF capacitor, which works at a working voltage of 400V, a high-voltage power supply output of about 13KV, and an output current of 2A as an example, 33-35 level Max modules need to be connected in series, then the capacitance of the high-voltage power supply is: C=10mF / 33=0.3mF, and its discharge voltage drop of 10ms is:

[0041]

[0042] Its voltage drop relative to 13KV is:

[0043] Among them, I OUT is the output current, C 串 is the equivalent capacitance of discharge, and t is the required high-voltage pulse width, that is, the discharge time.

[0044] It can be seen that the high-voltage power supply in the present application realizes a 10ms discharge window, and its voltage drops by 5%, which can achieve a relatively stable discharge window period.

[0045] The above embodiments are merely examples to illustrate that the high-voltage power supply of the present application can provide stable high-voltage pulses that match the stable plateau period of the plasma duration. If the pulse width of the high-voltage pulse needs to be extended, a capacitor with a larger capacity can be used to reduce the demand for voltage fluctuations of the high-voltage pulse.

[0046] In one embodiment, if Figure 2As shown, the Max module 111 may further include a driving power supply circuit 1114 , whose input end is connected to the energy storage capacitor 1111 , and whose output end is connected to the driving module 1113 , for converting the voltage of the energy storage capacitor 1111 into a power supply voltage of the driving module 1113 .

[0047] Exemplarily, the driving power supply circuit 1114 can use a DC conversion circuit to convert the voltage of the energy storage capacitor 1111 into the power supply voltage of the driving module 1113. As an exemplary embodiment, the DC conversion circuit can use a buck step-down circuit to convert the 400V energy storage capacitor 1111 voltage into the 24V voltage required by the driving module 1113. In this embodiment, the input and output of the DC conversion circuit can be based on the voltage value of the selected energy storage capacitor 1111 and the voltage value required by the driving module 1113. For example, an energy storage capacitor 1111 with a voltage of 450V / 500V / 700V can be used, and a driving module 1113 with a driving voltage of 12V / 15V can be used, which is not limited in this embodiment.

[0048] Since the voltage of the energy storage capacitor 1111 changes during the discharge process, in order to ensure that the driving module 1113 can be continuously powered, in one embodiment, the driving power supply circuit 1114 can use a wide-range input DC conversion circuit. During the continuous discharge of the energy storage capacitor 1111, even if the voltage of the energy storage capacitor 1111 drops, the DC conversion circuit can continue to output the voltage required by the driving module 1113.

[0049] In one embodiment, if Figure 2 As shown, in each level of Max module 111 , the full solid-state switch 1112 is connected in parallel with the energy storage capacitor 1111 , and the full solid-state switch 1112 is located at the input end side of the Max module 111 , and the energy storage capacitor 1111 is located at the output end side of the Max module 111 .

[0050] When discharge is required, the full solid-state switch 1112 in the current Max module 111 is turned on, and the current flows out from the positive electrode of the previous energy storage capacitor 1111, flows through the full solid-state switch 1112 of the current level, and reaches the negative electrode of the energy storage capacitor 1111 of the current level. If the full solid-state switch 1112 in the next Max module 111 is also in the turned-on state, the current reaches the negative electrode of the energy storage capacitor 1111 of the current level, and flows out from the positive electrode of the energy storage capacitor 1111 of the current level. The energy storage capacitor 1111 of the current level is connected in series with the energy storage capacitor 1111 of the previous level for output. If the full solid-state switches 1112 of the N-level Max modules 111 are all turned on, then N-1 energy storage capacitors 1111 are connected in series for output. Therefore, any high-voltage pulse can be output by simply increasing or decreasing the number of Max generators 110.

[0051] In one embodiment, if Figure 3As shown (taking the 3-level Max module 111 as an example for explanation), the Max module 111 also includes: a first diode D+ and a second diode D-, and the all-solid-state switch 1112 includes an IGBT tube Q; the cathode of the first diode D+ is connected to the anode of the energy storage capacitor 1111, and the anode of the first diode D+ is connected to the input end of the Max module 111 through the collector of the IGBT tube Q; the cathode of the second diode D- is connected to the cathode of the energy storage capacitor 1111 through the collector of the IGBT tube Q, and the anode of the second diode D- is connected to the input end of the Max module 111.

[0052] See below Figure 4 and Figure 5 (Take the 3-level Max module 111 as an example) to explain the charging process and the discharging process:

[0053] See also Figure 4 As shown, during charging, the all-solid-state switch 1112 is disconnected, and the current flows out from the DC charging power supply 121 and is divided into three parallel charging branches (see Figure 4 The parallel branches shown by the arrows in FIG. 1 ), wherein the first parallel branch L1 is: the current flows through the first-stage first diode D1+, into the positive electrode of the first-stage energy storage capacitor C1, and flows out from the negative electrode of the first-stage energy storage capacitor C1, and flows into the ground through the second-stage second diode D4- and the third-stage second diode D6- to charge the first-stage energy storage capacitor C1; the second parallel branch L2 is: the current flows through the first-stage first diode D1+ and the second-stage first diode D3+ into the positive electrode of the second-stage energy storage capacitor C2, and flows out from the negative electrode of the second-stage energy storage capacitor C2, and flows into the ground through the third-stage second diode D6- to charge the second-stage energy storage capacitor C2; the third parallel branch L3 is: flows through the first-stage first diode D1+, the second-stage first diode D3+ and the third-stage first diode D5+ into the positive electrode of the third-stage energy storage capacitor C3, and flows into the ground through the negative electrode of the third-stage energy storage capacitor C3 to charge the third-stage energy storage capacitor C3. Finally, the voltage of the energy storage capacitors at each stage is the charging voltage minus 3 times the diode voltage drop. Therefore, during the charging process, the charging voltages of the energy storage capacitors at each level are the same, and the Max modules 111 at each level are in a uniform state.

[0054] Below is a 450V / 10mF capacitor, which works at a working voltage of 400V, a charging current of 5A, and 33 Max modules are connected in series. The equivalent capacitance during parallel charging is: C = 10mF × 33 = 0.33F, and the charging time is:

[0055]

[0056] Among them, I IN is the charging current, C 并is the equivalent capacitance of the charge, V 单 is the operating voltage of a single capacitor.

[0057] The above embodiments are merely illustrative of the high-voltage power supply charging time of the present application. If the charging time needs to be shortened, the charging current may be further increased.

[0058] See also Figure 5 As shown, during discharge, the first diode D+ and the second diode D- in each level of the Max module 111 are reversely cut off, and the second-level all-solid-state switch 1112 is turned on. The current flows out from the positive electrode of the energy storage capacitor C1 of the first level, passes through the second-level all-solid-state switch Q2, reaches the negative electrode of the second-level energy storage capacitor C2, and flows out from the positive electrode of the second-level energy storage capacitor C2. After passing through the third-level all-solid-state switch Q3, it flows through the load from the first-level second diode D2- to form a loop, and then obtains twice the voltage of the DC charging power supply 121 to achieve high-voltage pulse output. In this embodiment, the microwave source can be used to build a corresponding number of levels for negative high-voltage requirements to meet the needs of the microwave source. For the specific discharge process, please refer to the formula description of the discharge process listed in the above embodiment.

[0059] In one embodiment, the charging circuit 120 includes a DC charging power supply 121 and a charging control switch S, wherein the control end of the charging control switch S is connected to the control system 130, and is closed when triggered by a charging instruction output by the control system 130 to turn on the charging circuit, and is disconnected when triggered by a stop charging instruction output by the control system 130 to disconnect the charging circuit.

[0060] In this embodiment, the charging control switch S can be a high-voltage switch, such as an IGBT, MOSFET or other power switch tube. When charging is required, the control system 130 can control the charging control switch S to be turned on, thereby turning on the charging circuit. When discharging is required, the control system 130 can control the charging control switch S to be turned off to prevent the negative high-voltage pulse from impacting the DC charging power supply 121 when the Max generator 110 is discharged.

[0061] In one embodiment, see Figure 6 As shown, the control system 130 may include a control module 131, which is connected to the driving circuit through a signal isolation circuit 140, and is used to output a trigger signal to the driving circuit. Since the all-solid-state switches 1112 at each level are at different potentials when working, and are all high-voltage levels, the trigger signals of the solid-state switches at each level need to be isolated. In this embodiment, the signal isolation circuit can use an optical fiber isolator or an optical coupler isolation circuit to isolate the trigger signal of each level.

[0062] In this embodiment, the control module 131 may include a main control unit 1311 and a trigger control unit 1312, wherein the main control unit 1311 is connected to the charging control switch S, and is used to control the DC charging power supply 121 to output and stop output by controlling the charging control switch S. The main control unit 1311 is also connected to the driving power supply circuit 1114, and is used to control the driving power supply circuit 1114 to supply power to the driving module 1113.

[0063] The main control unit 1311 is also connected to the trigger control unit 1312 and is used to control the trigger control unit 1312 to enable so that the trigger control module 131 controls the trigger timing of each solid-state switch in the Max generator 110 .

[0064] In one embodiment, the control system 130 may further include a monitoring module 132, which is connected to each level of the Max module 111, and is used to collect the state signal of the Max module 111. For example, the charging current signal, the discharging current signal, the real-time voltage signal, etc. of the Max module 111 can be collected, and the state signal can be transmitted to the controller in real time. The controller can detect in real time whether each level of the Max module 111 is in an overcurrent / overvoltage state based on the charging current signal, the discharging current signal and the voltage signal. When in an overcurrent or overvoltage state, the corresponding Max module 111 can be controlled to exit by triggering the control module 131. Exemplarily, when an overcurrent occurs in a Max module 111 of a certain level during the discharge process, the trigger control module 131 can control the full solid-state switch 1112 of this level to be disconnected, and the discharge current no longer passes through the energy storage capacitor 1111 of the previous level and the solid-state switch of this level, and is connected in series with the energy storage capacitor 1111 of this level through the second diode D- of this level. The discharge can continue.

[0065] In one embodiment, the monitoring module 132 may include a measuring unit and a monitoring unit, wherein the measuring unit may use an isolated current sensor, an isolated voltage sensor, a wireless temperature sensor, etc. to detect the voltage / current and temperature status of each Max module 111 and the Max generator 110 in real time, and upload them to the control module 131 in real time. The monitoring unit may display the voltage of the high-voltage power supply module, the high-voltage power supply temperature and environmental information based on an isolated sensor, such as a wireless temperature sensor, a voltage sensor camera, etc., and a program interface.

[0066] In one embodiment, an isolated sensor, such as a wireless temperature sensor, a wireless voltage sensor, a wireless current sensor, etc., can detect the voltage / current / temperature and other status signals of each Max module 111 and the Max generator 110 in real time, and send the status signal to the control module 131 through isolated transmission.

[0067] In one embodiment, since the plasma duration of the SUNIST tokamak device is about 20ms and the stable plateau period is about 10ms, in order to meet the plasma duration of the tokamak device, in this embodiment, the control system 130 needs to have a predetermined time control accuracy. For example, the time accuracy of the main control unit 1311 can be in the second level. Since the high-voltage power supply needs to have a high-speed on-off capability, the trigger control unit 1312 needs microsecond-level time accuracy. This ensures that the high-voltage power supply can accurately provide the negative high-voltage pulses required by the microwave source.

[0068] The present application also provides a microwave source system, such as Figure 7 and Figure 8 As shown, the microwave source may include a microwave generator and a microwave transmission line, wherein Figure 7 As shown, the microwave generator may include a cathode 240 for providing hot electrons. Also, the high voltage power supply 100 described in the above embodiments can apply an electric field to drive electrons to move, so as to generate microwaves.

[0069] In this embodiment, the microwave generator is described by taking a magnetron 200 as an example:

[0070] The magnetron 200 may include an anode for providing an axial magnetic field and a cathode 240 for providing thermal electrons; a high voltage power supply 100 is applied between the anode and the cathode 240 to form a radial electric field. The thermal electrons are emitted from the cathode 240, and move toward the anode driven by the radial electric field between the cathode 240 and the anode. During the movement, the thermal electrons are affected by the axial magnetic field, and drift motion occurs. During the drift motion, the electrons induce positive charge on one side of the resonant cavity slit, which is equivalent to charging the slit capacitor. The slit capacitor and the cavity inductance produce LC resonance, and the polarity of the charges on both sides of the slit changes periodically, which in turn affects the direction of the electron flow from the cathode 240, and finally forms a rotating cycloid orbit.

[0071] The LC resonance is coupled with the electron movement to reach a stable state, and the frequency of the resonance is the operating frequency of the magnetron 200. A metal ring or a metal wire is provided at the output end of the microwave generator, which is connected to the microwave transmission line as the output end, and the microwave oscillation in the resonance cavity is guided to the microwave transmission line. The microwave transmission line transmits the energy generated by the microwave generator to the antenna, and finally couples into the plasma to assist in heating the plasma.

[0072] In one embodiment, the electromagnet 210 generates a stable axial magnetic field. During operation, the resistance of the electromagnet 210 increases with the increase in temperature. In order to provide a stable axial magnetic field, in this embodiment, the electromagnet power supply 220 adopts a constant current power supply. For example, a constant current power supply with an operating current of approximately 7A can be used.

[0073] In one embodiment, the cathode power supply 230 supplies power to the cathode 240 to generate hot electrons, and the cathode 240 operates at a higher potential. Therefore, the cathode power supply 230 needs to be isolated and powered. In this embodiment, an isolation transformer 231 can be used for power supply. Figure 7 As shown, the AC power source is transformed by an isolation transformer 231, and the AC power source voltage is converted into the voltage required by the cathode 240, and rectified and filtered by a rectifier circuit 232 and a filter circuit 233. In this embodiment, the rectifier circuit 232 can adopt a full-bridge rectifier circuit or a half-bridge rectifier circuit. The filter circuit 233 can adopt an inductor filter. Through the rectifier circuit 232 and the filter circuit 233, the fluctuation of the cathode 240 current can be reduced, thereby reducing the impact of the cathode 240 current fluctuation on the microwave source power.

[0074] In one embodiment, the AC power source may be an AC power with adjustable voltage, for example, adjustable between 230 V and 250 V. The output voltage of the isolation converter may be about 10 V, and the cathode 240 current may be about 50 A.

[0075] In one embodiment, since the plasma duration of the SUNIST tokamak device is about 20ms and the stable plateau period is about 10ms, the microwave output is only about 10ms, and the time window is short, and it is difficult to adjust the cathode 240 current in a feedback manner according to the microwave source output power. Therefore, in this embodiment, the cathode power supply 230 needs to supply a continuous steady-state current, for example, to maintain the cathode 240 current at 50A. The steady-state working current will cause heat deposition to the rectifier circuit 232, the filter circuit 233 and the cathode 240. Therefore, in this embodiment, the cathode 240 and the cathode power supply 230 are installed with water cooling and / or air cooling to fully cool the cathode 240 and the cathode power supply 230 to prevent heat deposition from affecting the stable output of the microwave source.

[0076] In one embodiment, if Figure 8 As shown, the microwave transmission line includes: an excitation cavity 300, a circulator 500, a DC isolator 600, a ceramic window 700, an antenna 800 and a water load 900 connected to the circulator, which are connected in sequence; a directional coupler 400 is connected to at least one of the locations between the excitation cavity 300 and the circulator 500, between the DC isolator 600 and the ceramic window 700, and between the circulator 500 and the water load 900.

[0077] Specifically, the excitation cavity 300 is used to convert the microwave oscillation signal coaxially output by the microwave generator into a mode of a propagation signal in the waveguide. The directional coupler 400 can measure the microwave power of the transmission path. In this embodiment, three sets of directional couplers can be equipped to measure two groups of incident power and two groups of reflected power, and their directional coupling ratios are 70dB and 60dB respectively. The detector adopts a linear detector; the circulator 500 is used to prevent the reflected power of the subsequent microwave transmission line from entering the microwave generator and being absorbed by the water load; the DC isolator 600 is used to cut off the electrical connection between the microwave generator and the tokamak device. Since the grounding point of the high-voltage power supply 100 and the grounding point of the load are not at the same place, the potential of the tokamak device wall will change during the discharge of the high-voltage power supply 100. In order to protect various diagnoses on the tokamak device side and ensure that the measurement on the microwave generator side is not affected by the plasma, the electrical connection between the two is disconnected by the DC isolator; the function of the ceramic window 700 is to isolate the atmosphere and high vacuum, so that microwaves can pass through without loss; the antenna 800 transmits the microwaves in the waveguide in a direction, and its coupling with the vacuum chamber is optimized by adjusting the radial position of the antenna.

[0078] In one embodiment, based on the microwave source and the high voltage power supply 100 in the above embodiment, the working current of the electromagnet 210 is 6.4A, the input voltage of the cathode power supply 230 is 230V, the voltage of the single-stage Max module 111 in the high voltage power supply 100 is 375V, the output voltage of the high voltage power supply 100 is about -13kV, and the output current is 1.4A; according to the energy conversion efficiency of 80%, the microwave source output power is about 14.6kW. It is difficult to meet the requirement of the microwave source transient power (more than 30kw) required by the SUNIST Tokamak device.

[0079] It has been found through research that the current of the electromagnet 210, the input voltage of the cathode 240 and the voltage of each level of the Max module 111 of the high-voltage power supply 100 will have a great influence on the output power of the microwave source. Therefore, the output power of the microwave source can be adjusted by adjusting the current of the electromagnet 210, the input voltage of the cathode 240 and the voltage of each level of the Max module 111 of the high-voltage power supply 100.

[0080] In this embodiment, the power supply of the electromagnet 210 can be a constant current power supply with adjustable current, the cathode power supply 230 can be an AC power supply with adjustable voltage, the charging voltage of the DC charging power supply 121 in the high-voltage power supply 100 is adjustable, and further, the module voltage of each level of the Max module 111 is adjustable.

[0081] The output power of the microwave source is adjusted to more than 30KW by adjusting the current of the electromagnet 210, the input voltage of the cathode 240 and the voltage of each Max module 111 of the high-voltage power supply 100. For example, the working current of the electromagnet 210 can be adjusted to 6.6A, the input voltage of the cathode power supply 230 can be adjusted to 250V, the voltage of the single-stage Max module 111 of the high-voltage power supply 100 can be adjusted to 385V, the high voltage output of the high-voltage power supply 100 is about -13.5kV, and the output current is 3A (see the formula for calculating the discharge time in the above embodiment, the output current is 3A, if the voltage drops by about 5% or less during the discharge process, the sustainable discharge time is 5-7ms), according to the energy conversion efficiency of 80%, the microwave output power is estimated to be about 32.4kW, and the specific input waveform is as follows Fig. 9 shown.

[0082] Fig. 9 The output width set in is 5ms, which can be specifically controlled by controlling the timing of the output trigger signal by the trigger control module 131. During the pulse width output, the microwave maintains a stable high power output, and the output power is about 35kW. Fig. 9 The first waveform P1 in the figure; the microwave power measured by the directional coupler is about 37 kW, see Fig. 9 The error between the second waveform P2 and the second waveform P2 is 6%, which can meet the requirement of the microwave source transient power (above 30 kW) required by the SUNIST Tokamak device.

[0083] In this embodiment, the output power of the microwave source can be scanned by simultaneously scanning the working current of the electromagnet 210, the input voltage of the cathode power supply 230 and the voltage of the single-stage Max module 111 of the high-voltage power supply 100. The scanning result is as follows: Fig.10 The first fitting curve P shown re The microwave source output power can be between 10kW and 35kW, and the second fitting curve P obtained from the measurement results of the directional coupler in The result error is less than 1dB. At the same time, the reflected power is less than 1 / 10 of the incident power, and the coupling between the antenna and the vacuum chamber is good.

[0084] An embodiment of the present application also provides a microwave heating system, including the microwave source in the above embodiment, which generates higher microwave power through a microwave generator and couples it to the plasma through a microwave transmission line, thereby heating the plasma.

[0085] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A high voltage power supply for driving plasma, characterized in that: include: A Max generator having N levels of Max modules for outputting high voltage pulses, wherein the Max modules include energy storage capacitors, all-solid-state switches and drive modules, wherein the drive modules are powered by the energy storage capacitors in the Max modules of this level and are used to drive the all-solid-state switches, wherein N is a positive integer greater than 1; A charging circuit, connected to the Max generator, for charging the energy storage capacitor; A control system is connected to the Max generator and is used to control the charging and discharging process of the Max generator.

2. The high voltage power supply according to claim 1, characterized in that: The Max module also includes a driving power supply circuit, an input end of which is connected to the energy storage capacitor, and an output end of which is connected to the driving module, and is used for converting the voltage of the energy storage capacitor into a power supply voltage of the driving module.

3. The high voltage power supply according to claim 1 or 2, characterized in that: The reference potential end of the all-solid-state switch is connected to the negative electrode of the energy storage capacitor and is at the same potential.

4. The high voltage power supply according to claim 3, characterized in that: The Max module further comprises: a first diode and a second diode, and the all-solid-state switch comprises an IGBT; The cathode of the first diode is connected to the anode of the energy storage capacitor, and the anode of the first diode is connected to the collector of the IGBT and to the positive input terminal of the Max module; The cathode of the second diode is connected to the emitter of the IGBT, the anode of the first diode is connected to the negative output terminal of the Max module, and the emitter of the IGBT is connected to the cathode of the energy storage capacitor.

5. The high voltage power supply according to claim 4, characterized in that: The control system comprises: A controller, connected to the driving circuit via a signal isolation circuit, and configured to output a trigger signal to the driving circuit; The monitoring module is used to collect the status signal of the Max module and transmit it to the controller.

6. The high voltage power supply according to claim 1, characterized in that: The charging circuit includes a DC charging power supply and a charging control switch, wherein a control end of the charging control switch is connected to the control system, and the charging control switch is closed when triggered by a charging instruction output by the control system to turn on the charging circuit, and is opened when triggered by a stop charging instruction output by the control system to disconnect the charging circuit.

7. A microwave source, characterized in that: include: Microwave generators and microwave transmission lines; The microwave generator includes a cathode for providing hot electrons; and a high voltage power supply as claimed in claims 1 to 6, for applying an electric field to drive the electrons to move, so as to generate microwave oscillations of hot electrons; The microwave transmission line and the microwave generator output end are used to output the microwave oscillation.

8. The microwave source according to claim 7, characterized in that Also includes: A cathode power supply, used to provide a continuous steady-state current to the cathode, the power supply comprising an isolation transformer, a rectifier circuit and a filter circuit; The cathode includes a cooling device for cooling the rectifier circuit, the filter circuit and the cathode.

9. The microwave source according to claim 7, characterized in that: The microwave transmission line comprises: an excitation cavity, a circulator, a DC isolator, a ceramic window, an antenna and a water load connected to the circulator in sequence; A directional coupler is connected at least one of between the excitation cavity and the circulator, between the DC isolator and the ceramic window, and between the circulator and the water load.

10. A microwave heating system, characterized in that: include: The microwave source as described in any one of claims 7 to 9 is coupled to the plasma of a thermonuclear reaction device to heat the plasma.

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