Balancing field power supply and balancing power supply method for spherical tokamak

Abstract

The application discloses a kind of spherical tokamak's equilibrium field power supply, equilibrium power supply method, comprising: constant current source I3 with equilibrium field coil electric connection;Two groups of capacitor banks are respectively connected with equilibrium field coil, for supplying equilibrium field coil a steady-state low-level or high-level current balance high plasma current;Two groups of charge-discharge circuits are respectively connected with two groups of capacitor banks.Based on the equilibrium field power supply of spherical tokamak, the equilibrium power supply method of two groups of capacitors is used to supply power to the equilibrium field coil, so that the low plasma current is balanced by the equilibrium field current provided by constant current source I3, and the high plasma current is balanced by the equilibrium field current provided by two groups of capacitor banks.In the presence of low plasma current, ohmic field is put in, and plasma current is improved to a certain extent.In this way, the problems of limited volt-second product of spherical tokamak ohmic transformer, insufficient coil installation precision and stray field influence caused by vacuum wall eddy current can be compensated.

Description

Technical Field

[0001] This invention relates to the field of magnetic confinement fusion technology, and in particular to a balanced field power source and a balanced power supply method for a spherical tokamak. Background Technology

[0002] Nuclear fusion energy is safe, clean, and abundant. Magnetic confinement fusion based on tokamak devices is currently the most promising approach to the peaceful use of nuclear fusion energy. In 1986, Dr. Yuan-Kai Peng of Oak Ridge National Laboratory in Tennessee, USA, first proposed the concept of a spherical tokamak with a low toroidal ratio. The toroidal ratio of a tokamak device refers to the ratio of the large radius to the small radius of the device. The smaller the toroidal ratio, the more the plasma expands. This greatly increases the plasma current density, thus significantly improving the device's efficiency and allowing for a substantial reduction in the size of the fusion reactor. Furthermore, a lower toroidal ratio makes the entire plasma spherical, enabling more efficient utilization of magnetic energy and exhibiting superior magnetohydrodynamic stability. Future fusion reactors based on spherical tokamas can significantly reduce size and cost. In 1990, the Kalam Laboratory in the UK pioneered the construction of the world's first low toroidal ratio tokamak, START, and quickly achieved a toroidal specific pressure of 40%, three times that of any conventional tokamak, and its stability also surpassed that of conventional tokamas. Meanwhile, the compact spherical tokamak significantly reduced the construction and operating costs of the device. Subsequently, countries such as the United States, the United Kingdom, Russia, Japan, India, and Brazil competed to build more than 20 spherical tokams.

[0003] Considering the construction and operating costs of the NCST spherical tokamak, capacitor power supply is a more suitable choice. In plasma discharge experiments, the equilibrium field coil needs to provide a force that balances the natural expansion force of the plasma to confine it; its current plateau can balance the plasma current. Generally, plasma discharge conditions are quite demanding: vacuum gas supply must achieve a base pressure of approximately 1.33 × 10⁻³ Pa. The limited volt-seconds of the spherical tokamak ohmic field (due to the small installation space for the ohmic field coil), insufficient coil installation precision, and stray fields caused by vacuum wall eddies are all important factors affecting plasma discharge.

[0004] Existing balanced field power supply circuit structures have the following drawbacks in terms of power supply:

[0005] 1. It can only balance lower plasma currents;

[0006] 2. During the power supply process, the millisecond-scale time scale is difficult to balance with the low plasma current. Even if the balance is maintained, firstly, the balance is still on the millisecond-scale time scale; secondly, it is also difficult to balance the high plasma current again. Summary of the Invention

[0007] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a balanced field power source for a spherical tokamak.

[0008] The equilibrium field power source for a spherical tokamak according to a first aspect embodiment of the present invention includes:

[0009] Balanced field coil;

[0010] A constant current source I3 is electrically connected to a balancing field coil and is used to supply a steady-state low-level current to the balancing field coil to balance the low plasma current.

[0011] The second capacitor bank C2 is electrically connected to the balancing field coil and is mainly used for the ramp-up phase of the high-level current of the balancing field coil.

[0012] The second charging and discharging circuit is electrically connected to the second capacitor bank C2 and is used to charge and depressurize the second capacitor bank C2.

[0013] The first capacitor bank C1 is electrically connected to the balancing field coil and is used in conjunction with the second capacitor bank C2 to supply the balancing field coil with a high-level current platform to balance the high plasma current.

[0014] The first charging and discharging circuit is electrically connected to the first capacitor bank C1 and is used to charge and depressurize the first capacitor bank C1.

[0015] According to an embodiment of the present invention, the balancing field power supply of the spherical tokamak employs two sets of capacitors to power the balancing field coil: a second capacitor set C2 and a first capacitor set C1. The second capacitor set C2 is primarily responsible for the current ramp-up phase of the coil, enabling the balancing field coil to quickly reach the required current value. The first capacitor set C1, in conjunction with the second capacitor set C2, supplies a high-level current platform to the balancing field coil to balance high plasma currents. Low plasma currents are balanced by the balancing field current provided by the constant current source I3, while high plasma currents are balanced by the balancing field currents provided by both capacitor sets. When an ohmic field is applied in the presence of low plasma current, the plasma current is increased to a certain extent. This compensates for the limited volt-second count of the spherical tokamak ohmic transformer, insufficient coil installation precision, and the stray field effects caused by eddy currents in the vacuum wall.

[0016] According to some embodiments of the present invention, the first charge-discharge circuit includes:

[0017] A first charging circuit is electrically connected to the first capacitor bank C1 and is used to charge the first capacitor bank C1.

[0018] The first discharge circuit is electrically connected to the first capacitor bank C1 and is used to discharge the pressure from the first capacitor bank C1.

[0019] According to some embodiments of the present invention, the second charge-discharge circuit includes:

[0020] The second charging circuit is electrically connected to the second capacitor bank C2 and is used to charge the second capacitor bank C2.

[0021] The second discharge circuit is electrically connected to the second capacitor bank C2 and is used to discharge the pressure from the second capacitor bank C2.

[0022] According to some embodiments of the present invention, the first charging circuit includes a first equivalent resistor R1, a first charging module I1, a unidirectional conducting diode VD4, and a first switch J1. The first equivalent resistor R1, the first charging module I1, the unidirectional conducting diode VD4, and the first switch J1 are connected in series and then connected to a first capacitor bank C1 to charge the first capacitor bank C1 and make its charging process controllable.

[0023] According to some embodiments of the present invention, the first discharge circuit includes a first discharge resistor R2 and a second switch J2. The first discharge resistor R2 and the second switch J2 are connected in series and then connected in parallel with the first charging circuit to ensure that the voltage discharge process of the first capacitor bank C1 is controllable.

[0024] According to some embodiments of the present invention, the second charging circuit includes a second equivalent resistor R3, a second charging module I2, a unidirectional conducting diode VD5, and a third switch J3. The second equivalent resistor R3, the second charging module I2, the unidirectional conducting diode VD5, and the third switch J3 are connected in series and then connected to the second capacitor bank C2 to charge the second capacitor bank C2 and make its charging process controllable.

[0025] According to some embodiments of the present invention, the second discharge circuit includes a second discharge resistor R4 and a fourth switch J4. The second discharge resistor R4 and the fourth switch J4 are connected in series and then connected in parallel with the second charging circuit to ensure that the voltage discharge process of the second capacitor bank C2 is controllable.

[0026] According to some embodiments of the present invention, the balanced field coil is connected in series with a thyristor SCR and then connected to a second capacitor bank C2 or a first capacitor bank C1 to form a circuit, which is used to control the closing time of the discharge circuit of the first capacitor bank C1 or the second capacitor bank C2 to the balanced field coil.

[0027] According to some embodiments of the present invention, both the first capacitor bank C1 and the second capacitor bank C2 can be obtained by connecting a number of capacitors in parallel, so as to achieve a certain rated capacitance by equipping a large number of capacitors to maintain the current value required by the balanced field coil.

[0028] According to a second aspect of the present invention, a balanced power supply method includes power supply from the balanced field power source of the spherical tokamak described above, the specific details of which are as follows:

[0029] Construct a balanced field power supply architecture containing a spherical tokamak and set the preset current of the constant current source I3;

[0030] The first capacitor bank C1 and the second capacitor bank C2 are charged. The first switch J1 and the third switch J3 are closed to charge the first capacitor bank C1 and the second capacitor bank C2 of the equilibrium field to reach the preset voltage.

[0031] Start the constant current source I3 to provide a steady-state current in the hundreds of amperes to the balance field coil to balance the low plasma current driven by the microwave.

[0032] When the balanced microwave-driven plasma current is present, the first capacitor bank C1 and the second capacitor bank C2 are turned on to discharge the balanced field coil, providing a kiloampere-level balanced field coil current to balance the high plasma current.

[0033] After the plasma discharge is completed, the first switch J1 and the third switch J3 are disconnected and the second switch J2 and the fourth switch J4 are closed to discharge the excess electricity in the first capacitor bank C1 and the second capacitor bank C2.

[0034] The balanced power supply process of the balanced field power source has ended.

[0035] According to the balanced power supply method of this invention, the balanced field coil is selected to be powered in different ways at different discharge times based on different plasma currents and their discharge conditions. Low plasma currents are balanced by a constant current source, while high plasma currents are balanced by a capacitor bank. This compensates for the limited volt-second range of the spherical tokamak ohmic field, insufficient coil installation precision, and stray field effects caused by eddy currents in the vacuum wall. Therefore, the harsh discharge conditions are correspondingly improved, and the plasma current is increased to a certain extent.

[0036] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a diagram of the equilibrium field power supply system of a spherical tokamak according to an embodiment of the present invention;

[0039] Figure 2 This is a first charge / discharge circuit module diagram according to an embodiment of the present invention;

[0040] Figure 3 This is a second charge / discharge circuit module diagram according to an embodiment of the present invention;

[0041] Figure 4 This is a circuit diagram of the balanced field power supply for a spherical tokamak according to an embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram of a balanced power supply method according to an embodiment of the present invention.

[0043] Figure label:

[0044] First capacitor bank C1; Second capacitor bank C2; First charging module I1; Second charging module I2; Constant current source I3; Balanced field coil inductance L; Balanced field coil resistance R;

[0045] First equivalent resistance R1; First bleeder R2; First equivalent resistance R3; Second bleeder R4;

[0046] First switch J1; Second switch J2; Third switch J3; Fourth switch J4;

[0047] Unidirectional conduction diodes VD1 to VD6;

[0048] SCR (Syroscope Rectifier). Detailed Implementation

[0049] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0050] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0052] Example 1

[0053] See Figures 1 to 3 This embodiment provides a balanced field power source for a spherical tokamak, including:

[0054] Balanced field coil;

[0055] The constant current source I3 is electrically connected to the balancing field coil to supply a steady-state low-level current to the balancing field coil to balance the low plasma current.

[0056] The second capacitor bank C2 is electrically connected to the balancing field coil and is mainly used for the ramp-up phase of the high-level current of the balancing field coil.

[0057] The second charging and discharging circuit is electrically connected to the second capacitor bank C2. The second charging and discharging circuit includes a second charging circuit and a second discharging circuit. The second charging circuit is electrically connected to the second capacitor bank C2 and is used to charge the second capacitor bank C2. The second discharging circuit is electrically connected to the second capacitor bank C2 and is used to depressurize the second capacitor bank C2.

[0058] The first capacitor bank C1 is electrically connected to the balancing field coil and is used in conjunction with the second capacitor bank C2 to supply the balancing field coil with a high-level current platform to balance the high plasma current.

[0059] The first charging and discharging circuit is electrically connected to the first capacitor bank C1. The first charging and discharging circuit includes a first charging circuit and a first discharging circuit. The first charging circuit is electrically connected to the first capacitor bank C1 and is used to charge the first capacitor bank C1. The first discharging circuit is electrically connected to the first capacitor bank C1 and is used to depressurize the first capacitor bank C1.

[0060] According to an embodiment of the present invention, the balancing field power supply of the spherical tokamak employs two sets of capacitors to power the balancing field coil: a second capacitor set C2 and a first capacitor set C1. The second capacitor set C2 is primarily responsible for the current ramp-up phase of the coil, enabling the balancing field coil to quickly reach the required current value. The first capacitor set C1, in conjunction with the second capacitor set C2, supplies a high-level current platform to the balancing field coil to balance high plasma currents. Low plasma currents are balanced by the balancing field current provided by the constant current source I3, while high plasma currents are balanced by the balancing field currents provided by both capacitor sets. When an ohmic field is applied in the presence of low plasma current, the plasma current is increased to a certain extent. This compensates for the limited volt-second count of the spherical tokamak ohmic transformer, insufficient coil installation precision, and the stray field effects caused by eddy currents in the vacuum wall.

[0061] Example 2

[0062] See Figure 4 Based on Embodiment 1, this embodiment provides a balanced field power supply suitable for NCST (NanChang Spherical Tokamak) spherical tokamak. The first charging circuit includes a first equivalent resistor R1, a first charging module I1, a unidirectional conducting diode VD4, and a first switch J1. The first equivalent resistor R1, the first charging module I1, the unidirectional conducting diode VD4, and the first switch J1 are connected in series and then connected to the first capacitor bank C1 for charging the first capacitor bank C1.

[0063] The first discharge circuit includes a first discharge resistor R2 and a second switch J2. The first discharge resistor R2 and the second switch J2 are connected in series and then in parallel with the first charging circuit to ensure that the discharge of excess power in the first capacitor bank C1 is controllable.

[0064] The second charging circuit includes a second equivalent resistor R3, a second charging module I2, a unidirectional diode VD5, and a third switch J3. The second equivalent resistor R3, the second charging module I2, the unidirectional diode VD5, and the third switch J3 are connected in series and then connected to the second capacitor bank C2 to charge the second capacitor bank C2.

[0065] The second discharge circuit includes a second discharge resistor R4 and a fourth switch J4. The second discharge resistor R4 and the fourth switch J4 are connected in series and then connected in parallel with the second charging circuit to ensure that the discharge of excess power in the second capacitor bank C2 is controllable.

[0066] Specifically, unidirectional diodes VD1 and VD3 are connected close to the ends of the first capacitor bank C1 and the second capacitor bank C2, respectively, and unidirectional diode VD2 is connected in series between the first capacitor bank C1 and the second capacitor bank C2. A unidirectional diode VD6 is connected in series with the constant current source I3 to protect each circuit component.

[0067] Specifically, based on a further improvement of this embodiment, the balanced field coil is connected in series with a thyristor SCR and then connected to a second capacitor bank C2 or a first capacitor bank C1 to form a circuit.

[0068] Example 3

[0069] See Figure 1 or Figure 4 Based on the above embodiments, both the first capacitor bank C1 and the second capacitor bank C2 can be obtained by connecting several capacitors in parallel.

[0070] Example 4

[0071] See Figure 4 Based on Example 2, this embodiment provides a balanced field power supply suitable for NCST spherical tokamak, including the following details, as shown in Table 1:

[0072] Table 1: Key Components and Parameters of Balanced Field Power Supply

[0073] Components parameter Thyristor (SCR) The rated steady-state current is 4600kA Low-voltage capacitor bank (C1) 33000μF / 300V Low-voltage charging module (I1) 200V / 3A High-voltage capacitor bank (C2) 10000μF / 500V High-voltage charging module (I2) 400V / 1A Constant current source (I3) 30V / 500A

[0074] The balanced field power supply, which includes the above parameters and components, has achieved good results in plasma discharge experiments. The plasma current has been significantly improved, and the problems of limited volt-seconds of the NCST spherical tokamak ohmic field, insufficient coil installation accuracy, and stray field effects caused by vacuum wall eddy currents have been alleviated.

[0075] Example 5

[0076] See Figure 5 This embodiment provides a balanced power supply method, which includes powering the spherical tokamak using the balanced field power supply described in the above embodiment. The specific details are as follows:

[0077] Construct a balanced field power supply architecture containing a spherical tokamak and set the preset current of the constant current source I3;

[0078] The first capacitor bank C1 and the second capacitor bank C2 are charged. The first switch J1 and the third switch J3 are closed to charge the first capacitor bank C1 and the second capacitor bank C2 of the equilibrium field to reach the preset voltage.

[0079] Start the constant current source I3 to provide a steady-state current in the hundreds of amperes to the balance field coil to balance the low plasma current driven by the microwave.

[0080] When the microwave-driven plasma current is present, the first capacitor bank C1 and the second capacitor bank C2 are turned on to discharge the balancing field coil, providing a kiloampere-level balancing field coil current to balance the high plasma current.

[0081] After the plasma discharge is completed, the first switch J1 and the third switch J3 are disconnected and the second switch J2 and the fourth switch J4 are closed to discharge the excess electricity in the first capacitor bank C1 and the second capacitor bank C2.

[0082] The balanced power supply process of the balanced field power source has ended.

[0083] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0084] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0085] Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The reference to "embodiment" herein means that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily indicate the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0086] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A field coil power supply for a spherical tokamak, characterised in that, It comprises: a balance field coil; a constant current source I3 connected in parallel with the balance field coil; a second capacitor bank C2 connected in parallel with the balance field coil; a second charge-discharge circuit electrically connected with the second capacitor bank C2; a first capacitor bank C1 connected in parallel with the balance field coil; a first charge-discharge circuit electrically connected with the first capacitor bank C1.

2. A field-reversed configuration plasma confinement device according to claim 1, wherein the plurality of coils are arranged in a toroidal shape. The first charge-discharge circuit comprises: a first charging circuit electrically connected with the first capacitor bank C1; a first discharge circuit electrically connected with the first capacitor bank C1.

3. The balanced field power source for a spherical tokamak according to claim 1, characterized in that, The second charge-discharge circuit comprises: a second charging circuit electrically connected with the second capacitor bank C2; a second discharge circuit electrically connected with the second capacitor bank C2.

4. A field-reversed configuration plasma confinement device according to claim 2, wherein the plurality of coils are arranged in a toroidal shape. The first charging circuit comprises a first equivalent resistance R1, a first charging module I1, a unidirectional conducting diode VD4 and a first switch J1, which are connected in series and then connected to the first capacitor bank C1.

5. A field-reversed configuration (FRC) plasma generator according to claim 2, wherein, The first discharge circuit comprises a first discharge resistance R2 and a second switch J2, which are connected in series and then connected in parallel with the first charging circuit.

6. A field-reversed configuration plasma confinement device according to claim 3, wherein the plurality of coils are arranged in a toroidal shape. The second charging circuit comprises a second equivalent resistance R3, a second charging module I2, a unidirectional conducting diode VD5 and a third switch J3, which are connected in series and then connected to the second capacitor bank C2.

7. A field-reversed configuration plasma confinement device according to claim 3, wherein the plurality of coils are arranged in a toroidal shape. The second discharge circuit comprises a second discharge resistance R4 and a fourth switch J4, which are connected in series and then connected in parallel with the second charging circuit.

8. The balanced field power source for a spherical tokamak according to claim 1, characterized in that, The balance field coil is connected in series with a thyristor SCR and then connected to the second capacitor bank C2 or the first capacitor bank C1 to form a loop.

9. A field-reversed configuration plasma confinement device according to claim 1, wherein The first capacitor bank C1 and the second capacitor bank C2 can be obtained by connecting a plurality of capacitors in parallel.

10. A balance power supply method, comprising supplying power by using the balance field power supply of the spherical tokamak according to any one of claims 1-9, and the specific contents are as follows: Building a balance field power supply architecture containing a spherical tokamak, setting the preset current of the constant current source I3; Charging the first capacitor bank C1 and the second capacitor bank C2, closing the first switch J1 and the third switch J3, and charging the first capacitor bank C1 and the second capacitor bank C2 to reach the preset voltage; Starting the constant current source I3 to provide a steady-state current of the order of 100 A for the balance field coil to balance the microwave-driven low plasma current; When the balance microwave-driven plasma current exists, the first capacitor bank C1 and the second capacitor bank C2 are opened to discharge the balance field coil and provide a balance field coil current of the order of 1000 A for the balance field coil to balance the high plasma current. After the plasma discharge ends, the first switch J1 and the third switch J3 are opened, and the second switch J2 and the fourth switch J4 are closed, so as to discharge the excess electric quantity in the first capacitor set C1 and the second capacitor set C2; The balance power supply process of the balance field power supply is ended.

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