High voltage power supply, microwave source and microwave heating system

Abstract

A high voltage power supply, a microwave source and a microwave heating system. The high voltage power supply comprises: a Marx generator (110) configured to output a high-voltage pulse, wherein the Marx generator (110) comprises N stages of Marx modules (111), N being a positive integer greater than 1, each stage of the Marx module (111) comprises an energy storage capacitor (1111), an all-solid-state switch (1112) and a driving module (1113), and the driving module (1113) is powered by means of the energy storage capacitor (1111) in the current stage of the Marx module (111) and is configured to drive the all-solid-state switch (1112); a charging circuit (120) connected to the Marx generator (110) and configured to charge the energy storage capacitor (1111); and a control system (130) connected to the Marx generator (110) and configured to control the charging and discharging processes of the Marx generator (110).

Description

High voltage power supply, microwave source and microwave heating system 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. Background Art

[0002] In thermonuclear fusion technology, plasma must be heated to a sufficiently high reaction temperature. The traditional heating method is ohmic heating. However, as the plasma temperature rises during ohmic heating, the resistivity of the plasma decreases, and the heating efficiency decreases. Ohmic heating alone cannot reach the reactor temperature, and auxiliary heating methods must be used.

[0003] At present, for small magnetic confinement devices, such as tokamaks with a toroidal magnetic field of about 0.1T, electron cyclotron resonance auxiliary heating can usually be used, and the corresponding microwave source required is usually 2.45GHz. However, when using electron cyclotron resonance to assist in heating the plasma of a tokamak device, a stable microwave source is required. This requires not only that the high-voltage pulse power supply used can discharge stably but also that it has the ability to be turned on and off at high speed to match the duration of the plasma or the stable plateau period. The time scale for turning on and off the existing high-voltage power supply is usually on the order of seconds, which makes it impossible for the existing microwave source to achieve precise time control during the discharge process of the above-mentioned tokamak device. Therefore, how to make the microwave source better meet the time scale requirements of thermonuclear fusion has become a technical problem that needs to be solved urgently.

[0004] Summary of the Invention

[0005] The present application provides a high-voltage power supply, a microwave source, and a microwave heating system, which can enable the microwave source to meet the time scale requirements of thermonuclear fusion, thereby heating the plasma to a sufficiently high reaction temperature.

[0006] Some embodiments of the present application provide a high-voltage power supply, including:

[0007] A Max generator for outputting high-voltage pulses; wherein the Max generator comprises N levels of Max modules, where N is a positive integer greater than 1; wherein each level of the Max module comprises an energy storage capacitor, an all-solid-state switch, and a driving module; the driving module is powered by the energy storage capacitor in the Max module of this level to drive the all-solid-state switch;

[0008] a charging circuit, connected to the Max generator, for charging the energy storage capacitor;

[0009] A control system is connected to the Max generator and is used to control the charging and discharging process of the Max generator.

[0010] Other embodiments of the present application provide a microwave source, comprising: a microwave generator and a microwave transmission line; wherein the microwave generator includes a cathode for providing thermal electrons and the above-mentioned high-voltage power supply, which is used to apply an electric field to drive the electrons to move, so as to generate microwave oscillations of the thermal electrons; the microwave transmission line and the output end of the microwave generator are used to output the microwave oscillations.

[0011] Still other embodiments of the present application provide a microwave heating system, comprising: the above-mentioned microwave source, used to couple with the plasma of a thermonuclear reaction device to heat the plasma.

[0012] It can be seen that in the above scheme, the high-voltage power supply of the microwave source used for auxiliary heating of the plasma for thermonuclear fusion adopts a Max generator, in which the all-solid-state switch can achieve high-speed on-off speed. By adjusting the trigger signal of the solid-state switch, a stable discharge platform period that matches the stable platform period of the plasma can be accurately achieved, thereby meeting the time scale requirements of thermonuclear fusion.

[0013] Furthermore, by adjusting the voltages of the Max modules at each level in the Max generator of the high-voltage power supply, the microwave source can also meet the higher transient power requirements of thermonuclear fusion.

[0014] In addition, the energy storage capacitor in the Max module of this level is used to self-power the driver 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 the energy storage capacitor to self-power the driver 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 driver module, the driver 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 period, while high voltage does not exist during non-working period, thereby achieving passive safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] 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.

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] FIG1 is a schematic diagram of an exemplary structure of a high-voltage power supply according to some embodiments of the present application;

[0018] FIG2 is a schematic diagram of an exemplary structure of a Max module according to an embodiment of the present application;

[0019] FIG3 is a schematic diagram of an exemplary structure of a Max generator according to an embodiment of the present application;

[0020] FIG4 is an exemplary schematic diagram of the charging state of the high-voltage power supply according to an embodiment of the present application;

[0021] FIG5 is an exemplary schematic diagram of a high-voltage power supply discharge state according to an embodiment of the present application;

[0022] FIG6 is a schematic diagram of an exemplary structure of a high-voltage power supply according to other embodiments of the present application;

[0023] FIG7 is a schematic structural diagram of a microwave generator in a microwave source according to an embodiment of the present application;

[0024] FIG8 is a schematic structural diagram of a microwave transmission line in a microwave source according to an embodiment of the present application;

[0025] FIG9 is a waveform diagram of the microwave source output according to an embodiment of the present application;

[0026] FIG10 is a waveform diagram of microwave source output power scanning and detector measurement according to an embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the present application, the following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts should fall within the scope of protection of this application.

[0028] 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 sequential order. 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 a sequence other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof 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.

[0029] As previously mentioned, using electron cyclotron resonance to assist in heating the plasma of a tokamak requires a stable microwave source. Microwave power essentially comes from the drift motion of electrons, so its output power is sensitive to high-voltage input. Therefore, a high-voltage pulse power supply with stable discharge is required. Currently, research on tokamaks is still in the experimental stage, and the plasma duration is relatively short, for example, approximately 20 milliseconds, with a stable plateau period of around 10 milliseconds. Therefore, a high-voltage pulse power supply must be able to quickly switch on and off to match the plasma duration or stable plateau period. Existing high-voltage power supplies often use twelve-pulse rectification. Not only does their transient output power not meet the high transient power requirements of a tokamak, but their switching on and off timescales are typically on the order of seconds, making precise timing control difficult.

[0030] Other pulsed high-voltage power supplies, such as all-solid-state Max generators, have the ability to turn on and off at high speeds. 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 problems such as high- and low-potential isolation and mutual isolation of various power supplies. Generally, the design of steady-state isolated power supply is difficult. In order to reduce the difficulty of isolating the power supply between the all-solid-state switches, the power supply and triggering of its driving circuit often use the same circuit. However, using the same circuit for power supply and triggering can only provide transient power supply, which makes the pulse width of the high-voltage pulses of Max generators in the prior art often transient, usually in the nanosecond or microsecond level. The plateau period of the plasma duration stability of the present application is about 10ms. Therefore, the present application requires the high-voltage power supply to have a steady-state output or quasi-steady-state output in the millisecond range. For example, the high-voltage power supply needs to output a high-voltage pulse with a quasi-steady-state pulse width of 5-10ms. The all-solid-state Max generators in the prior art often cannot meet the high-voltage power supply requirements of the microwave source for heating the plasma of the tokamak device of the present application.

[0031] Based on this, this embodiment provides a high-voltage power supply that can be used to provide a negative high voltage for a microwave source that assists in heating thermonuclear fusion plasma, thereby driving the drift motion of electrons and generating microwave vibrations for heating the plasma in a tokamak device. Specifically, in the embodiments of this application, the tokamak device can be a SUNIST tokamak device.

[0032] FIG1 is a schematic diagram of the internal structure of a high-voltage power supply according to an embodiment of the present application. As shown in FIG1 , the high-voltage power supply may include: a Max generator 110 , a charging circuit 120 , and a control system 130 .

[0033] The Max generator 110 includes N Max modules 111 for outputting high-voltage pulses, where N is a positive integer greater than 1. In the embodiment of the present application, each Max module 111 may include a storage capacitor 1111, a solid-state switch 1112, and a driver module 1113. The driver module 1113 is powered by the storage capacitor 1111 of the Max module in that stage and is used to trigger the solid-state switch 1112 to close and open.

[0034] The charging circuit 120 is connected to the Max generator 110 and is used to charge the energy storage capacitor 1111 .

[0035] The control system 130 is connected to the Max generator 110 and is used to control the charging and discharging process of the Max generator 110 .

[0036] In the present application, 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 high-speed on-off speed. In this way, by adjusting the trigger signal of the solid-state switch, a stable discharge plateau period that matches the stable plateau period of the plasma can be accurately achieved. In addition, the energy storage capacitor in the Max module of this level is used to self-power the driver 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 the energy storage capacitor to self-power the driver 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 driver module, the driver module can continuously consume the energy of the energy storage capacitor. The energy of the energy storage capacitor is reduced to a safe level. High voltage exists during operation, while high voltage does not exist during non-operation, thereby achieving passive safety.

[0037] In some embodiments of the present application, the all-solid-state switch 1112 may be a fully controllable device, such as a GTR, an IGBT, a MOSFET, or a Darlington transistor.

[0038] In some embodiments of the present application, the energy storage capacitor 1111 may be an electrolytic capacitor. For example, the energy storage capacitor 1111 may be a 400V / 10mF electrolytic capacitor. Thus, the operating voltage of a single Max module 111 is 400V. Of course, the energy storage capacitor 1111 may also be other electrolytic capacitors. The specific voltage and capacitance of the electrolytic capacitor may be selected based on the requirements of the microwave source.

[0039] As an exemplary embodiment, one end of the all-solid-state switch 1112 is connected to a high potential, and the other end is connected to a low potential. Typically, the low potential end can be used as a reference potential end, for example, a ground end or a potential in the circuit. In some embodiments of the present application, the reference potential end of the all-solid-state switch 1112 is connected to the negative electrode of the energy storage capacitor 1111 and is connected to the same potential in the circuit, for example, ground.

[0040] FIG2 shows an exemplary structure of a Max module described in an embodiment of the present application. FIG3 shows an exemplary structure of a Max generator described in an embodiment of the present application. It should be noted that in FIG2 and 3, the above-mentioned all-solid-state switch 1112 using IGBT is used as an example for explanation, and the above-mentioned IGBT is marked as Q, Q2 or Q3 in FIG2 and 3. As shown in FIG2 and 3, the emitter of the IGBT is directly connected to the negative pole of the energy storage capacitor in this stage through a wire. When the energy storage capacitor at this stage supplies power to the driving module of the IGBT at 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 terminals can be directly connected to the negative pole of the energy storage capacitor.

[0041] When the Max generator 110 needs to be charged, the control system 130 controls the all-solid-state switches 1112 in each Max module 111 to open and controls the charging circuit 120 to charge the energy storage capacitors 1111. At this point, the energy storage capacitors 1111 in each Max module 111 are connected in parallel. When the Max generator 110 is discharging, the control system 130 controls the all-solid-state switches 1112 in a corresponding number of Max modules 111 to close based on the voltage demand of the microwave source. At this point, the energy storage capacitors 1111 in the corresponding number of Max modules 111 are connected in series to output the corresponding voltage.

[0042] As an exemplary embodiment, take a 450V / 10mF capacitor, which operates 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. The capacitance of the high-voltage power supply is: C = 10mF / 33 = 0.3mF, and its discharge voltage drop for 10ms is:

[0043] Its voltage drop relative to 13KV is:

[0044] Among them, I OUT is the output current; C 串 is the equivalent capacitance of discharge; t is the required high-voltage pulse width, that is, the discharge time.

[0045] It can be seen that the high-voltage power supply in this application realizes a 10ms discharge window, and its voltage drop is 5%, which can achieve a relatively stable discharge window period.

[0046] 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.

[0047] In some embodiments of the present application, as shown in Figure 2, 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 the power supply voltage of the driving module 1113.

[0048] Exemplarily, the above-mentioned driving power supply circuit 1114 can adopt 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 above-mentioned DC conversion circuit can adopt 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 determined 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.

[0049] Since the voltage of the energy storage capacitor 1111 changes during the discharge process, in order to ensure continuous power supply to the driver module 1113, in one embodiment, the driver power supply circuit 1114 can use a wide-range input DC conversion circuit. In this way, during the continuous discharge process 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 driver module 1113.

[0050] In some embodiments of the present application, as shown in Figures 2 and 3, the all-solid-state switch 1112 in each level of the Max module 111 is connected in parallel with the energy storage capacitor 1111, and the all-solid-state switch 1112 is located on the input side of the Max module 111, and the energy storage capacitor 1111 is located on the output side of the Max module 111.

[0051] When discharge is required, the all-solid-state switch 1112 in the current-stage Max module 111 is closed, and current flows from the positive electrode of the previous-stage energy storage capacitor 1111, flows through the current-stage all-solid-state switch 1112, and reaches the negative electrode of the current-stage energy storage capacitor 1111. If the all-solid-state switch 1112 in the next-stage Max module 111 is also closed, the current reaches the negative electrode of the current-stage energy storage capacitor 1111 and then flows out from the positive electrode of the current-stage energy storage capacitor 1111. The current-stage energy storage capacitor 1111 and the previous-stage energy storage capacitor 1111 are connected in series for output. If all the all-solid-state switches 1112 in N-stage Max modules 111 are closed, then N-1 energy storage capacitors 1111 are connected in series for output. Therefore, by simply increasing or decreasing the number of Max generator stages 110, any high-voltage pulse can be output.

[0052] In one embodiment, as shown in FIG3 (taking the three-level Max module 111 as an example for illustration), the Max module 111 further 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 positive electrode of the energy storage capacitor 1111, and the positive electrode 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 negative electrode of the energy storage capacitor 1111 through the collector of the IGBT tube Q, and the positive electrode of the second diode D- is connected to the input end of the Max module 111.

[0053] The charging and discharging processes are described below with reference to FIG4 and FIG5 (taking the 3-level Max module 111 as an example):

[0054] As shown in FIG4 , during charging, the all-solid-state switches 1112 in the Max modules 111 of each stage are disconnected, and the current flows out of the DC charging power supply 121 and is divided into three parallel charging branches (see the parallel branches indicated by the arrows in FIG4 ), wherein the first parallel branch L1 is: the current passes through the first diode D1+ of the first stage, flows 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, passes through the second diode D4- of the second stage and the third second diode D6- and flows into the ground to charge the first stage energy storage capacitor C1; the second parallel branch L1 is: the current passes through the first diode D1+ of the first stage, flows 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, passes through the second diode D4- of the second stage and the third second diode D6- and flows into the ground to charge the first stage energy storage capacitor C1; The connecting branch L2 is as follows: 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 as follows: the current 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 capacitor at each stage is the charging voltage minus 3 times the diode voltage drop. Therefore, during the charging process, the charging voltage of the energy storage capacitors at each stage is the same, and the Max modules 111 at each stage are in a uniform state.

[0055] Below is a 450V / 10mF capacitor, which works at a working voltage of 400V, a charging current of 5A, and is connected in series with 33 Max modules. The equivalent capacitance during parallel charging is: C = 10mF × 33 = 0.33F, and the charging time is:

[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 examples of the charging time of the high-voltage power supply of the present application. If the charging time needs to be shortened, the charging current may be further increased.

[0058] As shown in Figure 5, during discharge, the first diode D+ and the second diode D- in each level of the Max module 111 are reversely cut off, the second-level all-solid-state switch Q2 is closed, and the third-level all-solid-state switch Q3 is closed. The current flows out from the positive electrode of the first-level energy storage capacitor C1, 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, thereby obtaining twice the voltage of the DC charging power supply 121 and realizing high-voltage pulse output. In this embodiment, the corresponding number of stages can be built for the negative high-voltage demand of the microwave source 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. 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 charge control switch S can be a high-voltage switch, such as an IGBT, MOSFET, or other power switch. When charging is required, the control system 130 can control the charge control switch S to close, thereby activating the charging circuit. When discharging is required, the control system 130 can control the charge control switch S to open to prevent negative high-voltage pulses from impacting the DC charging power supply 121 during discharge of the Max generator 110.

[0061] In one embodiment, as shown in FIG6 , the control system 130 may include a control module 131 connected to the drive circuit via a signal isolation circuit 140 for outputting a trigger signal to the drive circuit. Because the all-solid-state switches 1112 at each level operate at different potentials, all at 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 may employ a fiber optic isolator or an optocoupler isolation circuit to isolate the trigger signals at each level.

[0062] In this embodiment, the control module 131 may include a main control unit 1311 and a trigger control unit 1312. The main control unit 1311 is connected to the charging control switch S and is configured to control the DC charging power supply 121 to start 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 configured 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 status signals 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 status signals 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. For example, 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 all-solid-state switch 1112 of the current 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 the current level, and is connected in series with the energy storage capacitor 1111 of the current level through the second diode D- of the current level. 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 Max generator 110 in real time, and upload the information to the control module 131 in real time. The monitoring unit may monitor each Max module 111 and Max generator 110 based on isolated sensors, such as wireless temperature sensors, voltage sensor cameras, etc., and a program interface displaying the voltage of the high-voltage power supply module, the temperature of the high-voltage power supply, and environmental information.

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

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

[0068] An embodiment of the present application also provides a microwave source system. In an embodiment of the present application, the microwave source system may include a microwave generator and a microwave transmission line, wherein the microwave transmission line is connected to the output end of the microwave generator. FIG7 shows an exemplary structure of a microwave generator in a microwave source according to an embodiment of the present application. FIG8 shows an exemplary structure of a microwave transmission line in a microwave source according to an embodiment of the present application. As shown in FIG7 , the microwave generator may include a cathode 240 for providing thermal electrons. Also, the high-voltage power supply 100 described in the above embodiment can apply an electric field to drive electron movement 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 cathode 240 to form a radial electric field. Thermal electrons are emitted from the cathode 240 and, driven by the radial electric field between the cathode 240 and the anode, move toward the anode. During this movement, they are affected by the axial magnetic field, causing the thermal electrons to drift. During this drift motion, electrons induce positive charges on one side of the resonant cavity slit, which is equivalent to charging the slit capacitance. The slit capacitance and the cavity inductance generate 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, ultimately forming a rotating cycloid orbit.

[0071] The LC resonance and electron motion are coupled to reach a stable state. The frequency of this resonance is the operating frequency of the magnetron 200. A metal ring or wire is provided at the output end of the microwave generator, which serves as the output end and is connected to the microwave transmission line. This output directs the microwave oscillations in the resonant cavity to the microwave transmission line. The microwave transmission line transmits the energy generated by the microwave generator to the antenna, which ultimately couples it into the plasma to provide auxiliary heating.

[0072] In one embodiment, the electromagnet 210 generates a stable axial magnetic field. During operation, the resistance of the electromagnet 210 increases with increasing 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, cathode power supply 230 supplies power to cathode 240 to generate thermal electrons, and cathode 240 operates at a relatively high potential. Therefore, cathode power supply 230 requires isolated power supply. In this embodiment, an isolation transformer 231 can be used for power supply. As shown in FIG7 , the AC power supply is transformed by isolation transformer 231 to convert the AC power supply voltage into the voltage required by cathode 240. The AC power supply voltage is then rectified and filtered by rectifier circuit 232 and filter circuit 233. In this embodiment, rectifier circuit 232 can be a full-bridge rectifier circuit or a half-bridge rectifier circuit. Filter circuit 233 can be an inductive filter. Rectifier circuit 232 and filter circuit 233 can reduce the fluctuation of cathode 240 current, thereby reducing the impact of 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 approximately 10 V, and the cathode 240 current may be approximately 50 A.

[0075] In one embodiment, because the plasma duration of a tokamak device is approximately 20 ms and the stable plateau period is approximately 10 ms, the microwave output is only approximately 10 ms, resulting in a short time window. This makes it difficult to implement feedback adjustment of the cathode 240 current based on the microwave source output power. Therefore, in this embodiment, the cathode power supply 230 is required to provide a continuous steady-state current, for example, to maintain the cathode 240 current at a stable level of 50 A. However, the steady-state operating current can cause heat deposition in components such as 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 equipped with water cooling and / or air cooling to fully cool them and prevent heat deposition from affecting the stable output of the microwave source.

[0076] In one embodiment, as shown in FIG8 , the microwave transmission line includes: an excitation cavity 300, a circulator 500, a DC block 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 block 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 sets of incident power and two sets of reflected power, with directional coupling ratios of 70 dB and 60 dB, respectively. The detector uses 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 isolate the electrical connection between the microwave generator and the tokamak device. Because the grounding point of the high-voltage power supply 100 and the grounding point of the load are not at the same point, the potential of the tokamak device wall will change during the discharge of the high-voltage power supply 100. To protect various diagnostics on the tokamak device side and ensure that measurements on the microwave generator side are 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, while allowing microwaves to pass through unimpeded. 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 described above, with an operating current of 6.4A for the electromagnet 210, an input voltage of 230V for the cathode power supply 230, and a voltage of 375V for the single-stage Max module 111 in the high-voltage power supply 100, the output voltage of the high-voltage power supply 100 is approximately -13kV, and the output current is 1.4A. Based on an energy conversion efficiency of 80%, the microwave source output power is estimated to be approximately 14.6kW. This is difficult to meet the transient power requirement of the microwave source (above 30kW) required by a tokamak device.

[0079] Research has found that the current of the electromagnet 210, the input voltage of the cathode 240, and the voltage of the Max modules 111 of each level of the high-voltage power supply 100 have a significant impact 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 the Max modules 111 of each level 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 furthermore, the module voltage of each level of the Max module 111 is adjustable.

[0081] The microwave source output power is adjusted to above 30 kW 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 operating current of the electromagnet 210 can be adjusted to 6.6 A, the input voltage of the cathode power supply 230 to 250 V, and the voltage of the single-stage Max module 111 of the high-voltage power supply 100 to 385 V. The high voltage output of the high-voltage power supply 100 is approximately -13.5 kV, and the output current is 3 A (see the formula for calculating the discharge time in the above embodiment. If the voltage drops by approximately 5% or less during the discharge process, the continuous discharge time is 5-7 ms). Based on an energy conversion efficiency of 80%, the microwave output power is estimated to be approximately 32.4 kW. The specific input waveform is shown in Figure 9.

[0082] The output width set in Figure 9 is 5ms, which can be specifically controlled by controlling the timing of the output trigger signal through 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, see the first waveform P1 in Figure 9; the microwave power measured by the directional coupler is about 37kW, see the second waveform P2 in Figure 9, and the error between the two is 6%, which can meet the requirement of the transient power of the microwave source (above 30kW) required by the tokamak device.

[0083] In this embodiment, the microwave source's output power is scanned by simultaneously scanning the operating 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 scan results are shown as the first fitting curve Pre in FIG10 . The microwave source output power can be output between 10 kW and 35 kW, and the error with the second fitting curve Pin obtained from the directional coupler measurement is less than 1 dB. Furthermore, the reflected power is less than 1 / 10 of the incident power, indicating good coupling between the antenna and the vacuum chamber.

[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 embodiment 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, comprising: A Max generator for outputting high voltage pulses; wherein the Max generator comprises N levels of Max modules, N being a positive integer greater than 1; wherein each level of Max module comprises an energy storage capacitor, a full solid-state switch and a driving module; the driving module is powered by the energy storage capacitor in the Max module of this level, and is used to drive the full solid-state switch; 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, wherein: The all-solid-state switch in each level of the Max module is connected in parallel with the energy storage capacitor.

3. The high voltage power supply according to claim 1 or 2, wherein: 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 2, wherein: The control system is used to control the all-solid-state switches in the N-level Max modules to be disconnected when the Max generator is charged, and to control the charging circuit to charge the energy storage capacitors in the N-level Max modules; and to control the corresponding number of all-solid-state switches in the N-level Max modules to be closed based on the voltage requirement of the microwave source when the Max generator is discharged, so that the corresponding number of energy storage capacitors are connected in series to output a voltage corresponding to the voltage requirement.

5. The high voltage power supply according to claim 1, wherein: The Max module also includes: A driving power supply circuit, whose input end is connected to the energy storage capacitor and whose output end is connected to the driving module, is used for converting the voltage of the energy storage capacitor into the power supply voltage of the driving module.

6. The high voltage power supply according to claim 1, wherein: The all-solid-state switch includes one of a GTR, an IGBT, a MOSFET, or a Darlington transistor.

7. The high voltage power supply according to claim 6, wherein: The all-solid-state switch comprises an IGBT; The Max module further includes: a first diode and a second diode; wherein, The cathode of the first diode is connected to the anode of the energy storage capacitor. The positive electrode of the pole tube is connected to the collector of the IGBT and connected 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.

8. The high voltage power supply according to claim 1, wherein: 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; and The monitoring module is used to collect the status signal of the Max module and transmit it to the controller.

9. The high voltage power supply according to claim 1, wherein: 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; and The charging control switch is closed when triggered by the charging instruction output by the control system to turn on the charging circuit; and is opened when triggered by the stop charging instruction output by the control system to disconnect the charging circuit.

10. A microwave source, comprising: Microwave generator and microwave transmission line; wherein, The microwave generator is used to apply an electric field to drive electron movement to generate microwave oscillations of hot electrons; wherein the microwave generator comprises a cathode for providing hot electrons and a high-voltage power supply according to any one of claims 1 to 9; The microwave transmission line is connected to the output end of the microwave generator and is used to output the microwave oscillation.

11. The microwave source of claim 10, further comprising: A cathode power supply, used for providing a continuous steady-state current to the cathode; The cathode power supply comprises: an isolation transformer, a rectifier circuit and a filter circuit.

12. The microwave source of claim 11, wherein: The cathode includes a cooling device for cooling the rectifier circuit, the filter circuit and the cathode.

13. The microwave source of claim 10, wherein: 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; Between the excitation cavity and the circulator, between the DC isolator and the ceramic window, A directional coupler is connected to at least one of the circulator and the water load.

14. A microwave heating system comprising: The microwave source according to any one of claims 10 to 13 is used to couple the plasma of a thermonuclear reaction device to heat the plasma.

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