Method for evaluating the effect of plasma toroidal rotation on tokamak hybrid operation

Abstract

The present invention relates to the field of plasma physics technology and discloses a method for evaluating the influence of plasma circumferential rotation on tokamak hybrid operation, comprising: designing the plasma current required for the hybrid operation of the tokamak device based on the parameters of the tokamak device and the auxiliary heating capacity; Ip and vertical field Bt The present invention comprises designing parameters for the neutral beam injection system and the electron cyclotron wave resonance system required for the tokamak's hybrid operation; injecting the initial neutral beam into the tokamak and performing integrated simulation calculations to obtain a first set of operating parameters for the tokamak's hybrid operation; adjusting the torque of the neutral beam injected into the tokamak to calculate a second set of operating parameters for the tokamak's hybrid operation; and analyzing and comparing the first set of operating parameters with the second set of operating parameters. The present invention can independently assess the impact of plasma toroidal rotation on the tokamak's hybrid operation.

Description

Technical Field

[0001] The present invention relates to the field of plasma physics technology, and in particular to a method for evaluating the influence of plasma toroidal rotation on tokamak mixing operation. Background Art

[0002] In modern tokamaks, plasma toroidal rotation plays a crucial role, crucial for plasma core confinement and MHD stability. First, low plasma toroidal rotation reduces Exo-B shear flow, which effectively suppresses drift wave turbulence and reduces energy and particle transport. Furthermore, low plasma toroidal rotation lowers the threshold for MHD (neoclassical tearing mode and resistive wall mode) instabilities. The plasma toroidal torque in tokamaks primarily comes from neutral beam injection. Future fusion reactors like ITER operate with relatively low toroidal rotation due to the low toroidal torque provided by their neutral beam injection (NBI) systems. Optimistic simulations of ITER indicate that its toroidal rotation is an order of magnitude lower than that of current tokamaks (such as DIIID and AUG). Low toroidal rotation can lead to poor confinement and MHD stability.

[0003] Experiments and simulations are commonly used to study the effects of plasma toroidal rotation on tokamak operation. In this study, forward and reverse injection of neutral beams are used to counteract plasma toroidal rotation. However, in both experiments and simulations, the reverse injection of the neutral beam reduces the neutral beam drive current, leading to changes in the safety factor q profile. It also results in increased fast ion losses, and both the q profile and the fast ion profile significantly impact turbulent transport and MHD performance. Consequently, other experimental and simulation studies have found it difficult to distinguish whether changes in the q profile, fast ions, or plasma toroidal rotation are responsible for altering plasma performance. Summary of the Invention

[0004] The present invention provides a method for evaluating the influence of plasma toroidal rotation on the mixed operation of a tokamak. The method can independently analyze the influence of plasma toroidal rotation on the confinement, transport and bootstrap current of the tokamak, and eliminate the influence of magnetic shear and fast ion changes brought by reverse neutral beam injection on the evaluation.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for evaluating the effect of plasma toroidal rotation on tokamak hybrid operation, comprising:

[0007] S1. Set initial conditions;

[0008] S2. Under the initial conditions, design the plasma current required for the mixed operation of the tokamak device based on the parameters of the tokamak device and the auxiliary heating capacity. Ip and vertical field Bt ;

[0009] S3. Designing parameters of the neutral beam injection system and the electron cyclotron wave resonance system required for the hybrid operation of the tokamak device to obtain relevant parameters of the initial neutral beam and the electron cyclotron wave injected into the tokamak device;

[0010] S4, injecting the initial neutral beam into the tokamak device and calculating using an integrated simulation method to obtain a first set of operating parameters of the tokamak device during hybrid operation;

[0011] S5. Injecting the complete positive initial neutral beam into the neutral beam injection system P NB The first neutral beam is divided into a first neutral beam and a second neutral beam with opposite injection directions, the same cutting radius, injection angle and fast ion fraction, and the injection power is half of the injection power of the initial neutral beam; the first neutral beam P NB1 The injection direction is completely forward, and the second neutral beam P NB2 The injection direction is completely reverse, and the ohmic current compensates for the loss of the reverse driving current of the second neutral beam;

[0012] S6. Adjusting the torque of the neutral beam injected into the tokamak device to adjust the plasma toroidal rotation speed, and calculating a second set of operating parameters of the tokamak device during hybrid operation;

[0013] S7. Analyze and compare the first set of operating parameters and the second set of operating parameters to obtain the results of the effects of different plasma toroidal rotations on the mixed operation of the tokamak device.

[0014] As an optimization, the specific steps of S3 are:

[0015] By integrating simulation calculation methods and combining the q profile required for the mixed operation of the tokamak device, the parameters of the neutral beam injection system and electron cyclotron wave resonance system required for the mixed operation of the tokamak device are designed to obtain the relevant parameters of the initial neutral beam and electron cyclotron wave injected into the tokamak device.

[0016] As an optimization, the integrated simulation calculation method includes integrated calculation of balance, transport, auxiliary heating and current drive.

[0017] As an optimization, the initial neutral beam related parameters include the power of the initial neutral beam injection PNB , tangential radius and energy, etc., the power of electron cyclotron wave P EC , frequency and emission angle.

[0018] As an optimization, the first set of operating parameters and the second set of operating parameters both include a constraint improvement factor H 98(y,2) , normalized specific pressure β N , polar specific pressure β p , bootstrap current share f BS , plasma linear average density, plasma energy storage W th , energy constraint time τ e and ion temperature Ti .

[0019] As an optimization, in S6, the torque of the neutral beam injected into the tokamak device is adjusted by adjusting the injection power ratio of the first neutral beam and the second neutral beam.

[0020] As an optimization, the combination of the injection powers of the first neutral beam and the second neutral beam includes:

[0021] a) P NB1 =P NB ，P NB2 =0；

[0022] b) P NB1 =3 / 4P NB ，P NB2 =1 / 4P NB ；

[0023] c) P NB1 =1 / 2P NB ，P NB2 =1 / 2P NB ；

[0024] d) P NB1 =1 / 4P NB ，P NB2 =3 / 4PNB ；

[0025] e) P NB1 =0 ，P NB2 =P NB 。

[0026] As an optimization, in S6, when adjusting the torque of the neutral beam injected into the tokamak device, the parameters of the electron cyclotron wave heating and the current drive are kept unchanged.

[0027] As an optimization, the initial conditions include plasma electron temperature, plasma ion temperature, and density profile.

[0028] As an optimization, it also includes:

[0029] S8. Change the initial conditions and repeat S2-S7 to obtain the results of the effects of different plasma circumferential rotations on the mixed operation of the tokamak device under different initial conditions, and finally obtain a comprehensive analysis result of the effects of plasma circumferential rotation on the mixed operation of the tokamak device.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] The present invention provides a method for evaluating the influence of plasma circumferential rotation on the mixing operation of a tokamak. By combining forward and reverse injection of a neutral beam, the method provides the influence of different circumferential rotations of the corresponding plasma on the mixing operation under different momentum injections of the neutral beam.

[0032] The present invention uses a program to simulate the neutral beam heating and current drive process, which can maintain the same fast ion fraction in the reverse and forward neutral beams. In the integrated simulation, the ohmic current can be used to maintain the same mixed operation q profile for the forward and reverse neutral beams. This method can eliminate the influence of magnetic shear and fast ion fraction on the research in the original experimental and simulation studies. Therefore, it can independently analyze the influence of plasma toroidal rotation on the tokamak mixing operation, eliminating the interference of magnetic shear, fast ion and alpha effects on the research.

[0033] The present invention can evaluate the impact of plasma toroidal rotation on mixing operation under different initial conditions (including when the profile parameters are very low in the initial stage of discharge, the profile parameters include plasma electron temperature, ion temperature, and density profile). Since the plasma toroidal rotation of ITER may not be high from the beginning to the end of discharge, this research method of the present invention can provide support for the experimental operation of ITER and future fusion reactors. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings:

[0035] Figure 1 This is a flow chart of a method for evaluating the effect of plasma toroidal rotation on tokamak mixing operation according to the present invention;

[0036] Figure 2 Schematic diagram of injecting plasma current into the first neutral beam and the second neutral beam. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention. Example

[0038] A method for evaluating the effect of plasma toroidal rotation on tokamak hybrid operation, comprising:

[0039] S1. Set initial conditions. In this embodiment, the initial conditions include plasma electron temperature, plasma ion temperature, and density profile.

[0040] S2. Under the initial conditions, design the plasma current required for the mixed operation of the tokamak device based on the parameters of the tokamak device and the auxiliary heating capacity. Ip and vertical field Bt ;

[0041] S3. Design the parameters of the neutral beam injection system and the electron cyclotron wave resonance system required for the mixed operation of the tokamak device, so as to obtain the relevant parameters of the initial neutral beam and the electron cyclotron wave injected into the tokamak device; specifically, through an integrated simulation calculation method (wherein the integrated simulation includes the integrated calculation of multiple programs such as balance, transport, auxiliary heating and current drive), combined with the q profile required for the mixed operation of the tokamak device, design the parameters of the neutral beam injection system and the electron cyclotron wave resonance system required for the mixed operation of the tokamak device, so as to obtain the relevant parameters of the initial neutral beam and the electron cyclotron wave injected into the tokamak device, including the power PNB, tangent radius and energy of the initial neutral beam injection, the power PEC, frequency and emission angle of the electron cyclotron wave.

[0042] S4, injecting the initial neutral beam into the tokamak device and performing integrated simulation calculation to obtain a first set of operating parameters of the tokamak device during mixed operation, the first set of operating parameters including a constraint improvement factor H 98(y,2) , normalized specific pressure β N , polar specific pressure β p , bootstrap current share f BS , plasma linear average density, plasma energy storage W th , energy constraint time τ e and ion temperature Ti .

[0043] S5. Injecting the complete positive initial neutral beam into the neutral beam injection system P NB The first neutral beam is divided into a first neutral beam and a second neutral beam with opposite injection directions, the same cutting radius, injection angle and fast ion fraction, and the injection power is half of the injection power of the initial neutral beam; the first neutral beam P NB1 The injection direction is completely forward, and the second neutral beam P NB2 The injection direction is completely reversed, and the ohmic current compensates for the loss of the reverse drive current of the second neutral beam. Using integrated simulation methods, the ohmic current profile is artificially adjusted to compensate for the loss of the reverse drive current of the neutral beam. The terms "neutral beam forward" and "reverse" in this invention refer to whether the neutral beam direction is the same as or opposite to the plasma current direction. A forward neutral beam direction is defined as the same as the plasma current direction, while a reverse neutral beam direction is defined as the reverse neutral beam direction.

[0044] When using the program to simulate the neutral beam heating and current driving process, the reverse and forward neutral beams can be maintained with the same fast ion fraction; in the integrated simulation, the ohmic current can be used to maintain the forward and reverse neutral beams with the same mixed operation q profile.

[0045] The forward direction here means that the injection direction of the neutral beam is the same as the current direction of the plasma current. Similarly, the reverse direction means that the injection direction of the neutral beam is opposite to the current direction of the plasma current.

[0046] Specifically, such as Figure 2 As shown, the original neutral beam injected in S4 is changed to two beams, which are called the first neutral beam and the second neutral beam. The injection direction of the first neutral beam is the same as the direction of the plasma current, and its power is P NB1, the injection direction of the second neutral beam is opposite to the direction of the plasma current, and the power is P NB2 , the specific injection process is as follows:

[0047] (1) When the original forward neutral beam is changed from one beam to two beams, the total power injected by the neutral beam system is kept unchanged, that is, ( P NB1 + P NB2 ) = P NB , the first neutral beam P NB1 With the second neutral beam P NB2 Have the same cutting radius and injection angle;

[0048] (2) When adding the reverse injection of the second neutral beam, the ohmic current compensates for the loss of the reverse driving current of the second neutral beam, maintaining the current density profile of the core unchanged, that is, maintaining the magnetic shear of the core unchanged, eliminating the change of magnetic shear caused by the reverse injection of the neutral beam;

[0049] (3) When injecting neutral beams to simulate neutral beam heating and current drive, the first and second neutral beams should have the same fast ion fraction, eliminating the factor of more fast ion loss caused by the reverse injection of the second neutral beam during the experiment, so as to avoid affecting the analysis results of the tokamak operation due to fast ions;

[0050] S6. Adjust the torque of the neutral beam injected into the tokamak device to adjust the plasma circumferential rotation speed, and calculate a second set of operating parameters of the tokamak device during hybrid operation; the second set of operating parameters includes a confinement improvement factor H 98(y,2) , normalized specific pressure β N , bootstrap current share f BS , plasma energy storage W th and ion temperature Ti wait.

[0051] In this embodiment, the torque of the neutral beam injected into the tokamak device is adjusted by adjusting the injection power ratio of the first neutral beam and the second neutral beam, thereby changing the plasma toroidal rotation speed. The plasma toroidal rotation speed can be adjusted from a positive larger value (1.2×10 5 rad / s) gradually changes to zero circumferential rotation, and then from zero circumferential rotation to the direction of plasma rotation being opposite to the direction of plasma current, so as to analyze the effects of different plasma circumferential rotations on the hybrid operation of the tokamak device.

[0052] In this embodiment, the combination of the injection powers of the first neutral beam and the second neutral beam includes:

[0053] a) P NB1 =P NB ，P NB2 =0；

[0054] b) P NB1 =3 / 4P NB ，P NB2 =1 / 4P NB ；

[0055] c) P NB1 =1 / 2P NB ，P NB2 =1 / 2P NB ；

[0056] d) P NB1 =1 / 4P NB ，P NB2 =3 / 4P NB ；

[0057] e) P NB1 =0 ，P NB2 =P NB 。

[0058] While varying the neutral beam injection torque, the parameters of electron cyclotron wave heating and current drive (electron cyclotron wave power PEC, frequency, and emission angle) were maintained constant. The second operating parameters of tokamaks operating in hybrid mode with varying plasma toroidal rotation were then analyzed and compared. This second operating parameter broadly refers to the operating parameters of the tokamak operating in hybrid mode after varying the neutral beam, and therefore can vary widely.

[0059] S7. Analyze and compare the first set of operating parameters and the second set of operating parameters to obtain the results of the effects of different plasma toroidal rotations on the mixed operation of the tokamak device.

[0060] S8. Change the initial conditions and repeat S2-S7 to obtain the results of the effects of different plasma circumferential rotations on the mixed operation of the tokamak device under different initial conditions, and finally obtain a comprehensive analysis result of the effects of plasma circumferential rotation on the mixed operation of the tokamak device.

[0061] Evaluate the effect of the initial profile on the plasma toroidal rotation. Using different plasma temperature and density profiles as initial conditions, repeat the above steps S2-S7 to analyze and compare the effect of plasma toroidal rotation on the mixing operation under different initial conditions. Using different plasma temperature and density profiles as initial conditions, the plasma temperature and density profiles change from low to high, and the corresponding plasma confinement also changes from low to high. The effect changes from weak to strong, and finally a comprehensive analysis result of the influence of plasma toroidal rotation on the hybrid operation of the tokamak device is obtained. The effect is determined by the plasma temperature and density profile, which is existing technology and will not be described in detail here.

[0062] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for evaluating the effect of plasma toroidal rotation on tokamak mixing operation, characterized in that: include: S1. Set initial conditions; S2. Under the initial conditions, design the plasma current required for the mixed operation of the tokamak device based on the parameters of the tokamak device and the auxiliary heating capacity. IP and vertical field Bt ; S3. Designing parameters of the neutral beam injection system and the electron cyclotron wave resonance system required for the hybrid operation of the tokamak device to obtain relevant parameters of the initial neutral beam and the electron cyclotron wave injected into the tokamak device; S4, injecting the initial neutral beam into the tokamak device and performing integrated simulation calculation to obtain a first set of operating parameters of the tokamak device during hybrid operation; S5. Injecting the complete positive initial neutral beam into the neutral beam injection system P NB The first neutral beam is divided into a first neutral beam and a second neutral beam with opposite injection directions, the same cutting radius, injection angle and fast ion fraction, and the injection power is half of the injection power of the initial neutral beam; the first neutral beam P NB1 The injection direction is completely forward, and the second neutral beam P NB2 The injection direction is completely reverse, and the ohmic current compensates for the loss of the reverse driving current of the second neutral beam; S6. Adjusting the torque of the neutral beam injected into the tokamak device to adjust the plasma toroidal rotation speed, and calculating a second set of operating parameters of the tokamak device during hybrid operation; S7. Analyze and compare the first set of operating parameters and the second set of operating parameters to obtain the results of the effects of different plasma toroidal rotations on the mixed operation of the tokamak device.

2. The method for evaluating the effect of plasma toroidal rotation on tokamak mixing operation according to claim 1, characterized in that: The specific steps of S3 are: By integrating simulation calculation methods and combining the q profile required for the mixed operation of the tokamak device, the neutral beam injection system and electron cyclotron wave resonance system parameters required for the mixed operation of the tokamak device are designed to obtain the initial neutral beam related parameters injected into the tokamak device.

3. The method for evaluating the effect of plasma toroidal rotation on tokamak mixing operation according to claim 2, characterized in that: The integrated simulation calculation method includes integrated calculation of balance, transport, auxiliary heating and current drive.

4. The method for evaluating the effect of plasma toroidal rotation on tokamak mixing operation according to claim 2, characterized in that: The initial neutral beam related parameters include the power of the initial neutral beam injection P NB , tangential radius and energy, power of electron cyclotron wave P EC , frequency and emission angle.

5. The method for evaluating the effect of plasma toroidal rotation on tokamak mixing operation according to claim 1, characterized in that: The first set of operating parameters and the second set of operating parameters both include a constraint improvement factor H 98(y,2) , normalized specific pressure β N , polar specific pressure β p , bootstrap current share f BS , plasma linear average density, plasma energy storage W th , energy constraint time τ e and ion temperature Ti .

6. The method for evaluating the effect of plasma toroidal rotation on tokamak mixing operation according to claim 1, characterized in that: In S6 , the torque of the neutral beam injected into the tokamak device is adjusted by adjusting the injection power ratio of the first neutral beam and the second neutral beam.

7. The method for evaluating the effect of plasma toroidal rotation on tokamak mixing operation according to claim 6, characterized in that: The combination of the injection powers of the first neutral beam and the second neutral beam includes: P NB1 =P NB ，P NB2 =0； P NB1 =3 / 4P NB ，P NB2 =1 / 4P NB ； P NB1 =1 / 2P NB ，P NB2 =1 / 2P NB ； P NB1 =1 / 4P NB ，P NB2 =3 / 4P NB ； P NB1 =0 ，P NB2 =P NB 。 8. The method for evaluating the effect of plasma toroidal rotation on tokamak mixing operation according to claim 2, characterized in that: In S6, when adjusting the torque of the neutral beam injected into the tokamak device, the parameters of the electron cyclotron wave heating and the current drive are kept unchanged.

9. The method for evaluating the effect of plasma toroidal rotation on tokamak mixing operation according to claim 1, characterized in that: The initial conditions include plasma electron temperature, plasma ion temperature, and plasma density profile.

10. A method for evaluating the effect of plasma toroidal rotation on tokamak mixing operation according to any one of claims 1 to 9, characterized in that: Also includes: S8. Change the initial conditions and repeat S2-S7 to obtain the results of the effects of different plasma circumferential rotations on the mixed operation of the tokamak device under different initial conditions, and finally obtain a comprehensive analysis result of the effects of plasma circumferential rotation on the mixed operation of the tokamak device.

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