Cooperative control method for improving tokamak radio frequency wave current driving locality

Abstract

The invention discloses a cooperative control method for improving Tokamak radio frequency wave current driving locality, and the method mainly comprises the following steps: S1, according to a radial position where locality needs to be enhanced, heating narrow resonance layer electrons at the corresponding radial position through electron cyclotron resonance heating (ECRH); s2, ion cyclotron resonance heating (ICRH) is adjusted for regional heating, so that the radial position of an ICRH driving current main peak value coincides with the radial position of an ECRH current peak value; s3, using GENRAY and CQL3D programs to simulate low hybrid wave (LHW) and high harmonic fast wave (HHFW) combined current driving, calculating a momentum region corresponding to a synergistic effect in a momentum space, performing correlation analysis on the synergistic momentum region, wave emission parameters and current radial distribution, feeding back the parameter adjustment direction, and performing repeated iteration until required local current distribution is achieved; according to the invention, current driving with consideration of driving efficiency and locality control is realized, and the method is of great significance in enhancing the current distribution control capability, improving the constraint performance of plasma and obtaining longer constraint time and higher fusion power.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear fusion reactors, and specifically to a cooperative control method for enhancing the locality of radio frequency wave current drive in a tokamak. Background Art

[0002] The ultimate step of China's energy "trilogy" strategy is a fusion reactor. In an advanced tokamak fusion reactor, the plasma must operate in a high-performance steady state under a corresponding magnetic field configuration. The key to generating these configurations is to control the current distribution of the plasma, and radio frequency wave current drive is an important means to control the plasma current distribution. The locality of its driven current distribution directly affects the shape of the current distribution, the magnitude of the current, and the driving efficiency. Enhancing the ability to control the locality of radio frequency wave-driven current is of great significance for the development of nuclear fusion technology.

[0003] Currently, the radio frequency waves widely used in tokamaks for driving current mainly include ion cyclotron waves, high harmonic fast waves, lower hybrid waves, and electron cyclotron waves. Among them, ion cyclotron waves can directly heat ions and can also add electrons through Landau damping and transit-time magnetic pumping, but the current driving efficiency is currently not as good as that of lower hybrid wave current drive, and the ion cyclotron antenna is extremely prone to arc ablation; the peak of the high harmonic fast wave can be closer to the core and has a relatively high driving efficiency, but the current driving efficiency is also currently not as good as that of lower hybrid waves, and its current distribution is relatively wide and the locality is relatively poor; although the lower hybrid wave current drive currently has the highest driving efficiency, in most cases, the distribution of the lower hybrid wave-driven current is relatively dispersed, especially in the core, and usually cannot form a strong local single peak with a small radial distribution range, and the locality is relatively poor and not easy to control; the electron cyclotron wave has strong localization, but its driven current distribution is relatively narrow and cannot drive electrons within a certain local range outside the narrow resonance region.

[0004] Currently, the experimental cooperative heating mainly aims to improve the current drive efficiency. The module for local control feedback has not been added to the mature current calculation code. There are few studies on the experiment and simulation of controlling the locality of the current distribution in a cooperative manner. Or while obtaining locality, the current drive efficiency is sacrificed, and the radial range of regulation is very limited. This method simultaneously gives the control of locality at the core and off-axis positions and takes into account a relatively high current drive efficiency. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a cooperative control method for enhancing the localization of tokamak radio-frequency wave current drive, which solves the problem of insufficient localization control ability of the current distribution in the current tokamak; takes into account the improvement of the cooperative current drive efficiency and the localization control ability; adds a new method for dividing different physical mechanism drives and cooperative currents in momentum space and adding localization control feedback parameters to the mature ray tracing and electron distribution function solving codes GENRAY and CQL3D; and makes a technical contribution to the enhancement of the fusion tokamak current distribution control ability.

[0006] To achieve the above objectives, the present invention is realized through the following technical solutions: A cooperative control method for enhancing the localization of tokamak radio-frequency wave current drive, including a cooperative control method for current drive and current distribution, specifically including the following steps: S1. According to the radial position where localization needs to be enhanced, heat the electrons in the narrow resonance layer at the corresponding radial position by ECRH; S2. Adjust ICRH for regional heating, improve the ion and electron temperatures, which is beneficial to enhancing the localization of ICW, LHW, and HHFW, and try to make the radial position of the current peak of ICCD coincide with the radial position of the current peak of ECRH; S3. LHW and HHFW are driven cooperatively. Given a certain low hybrid wave frequency, select a helical wave with an appropriate frequency; or given a certain helical wave frequency, select a low hybrid wave with an appropriate frequency. The specific implementation method is as follows: First, give the initial frequencies of the two waves. Generally, combined with the device conditions, select a similar HHFW frequency according to the fixed LHW frequency; or select a similar LHW frequency according to the fixed HHFW frequency, and substitute them into the ray tracing and Fokker-Planck equations respectively. Use the simulation software package GENRAY / CQL3D to calculate the cooperative drive current of HHFW+LHW. The GENRAY program is used to track the dynamic evolution process of the wave trajectory, and the CQL3D program is used to calculate the solution of the electron distribution function in the two-dimensional momentum space of the Fokker-Planck equation. The purpose is to successfully add the quasilinear wave diffusion term of LHW+HHFW and the contribution terms of the two waves into the Fokker-Planck equation to establish a cooperative drive model. The Fokker-Planck equation used in the simulation is as follows: ; In the formula, u represents the normalized electron momentum, , The subscript , represents parallel and perpendicular, referring to the magnetic field direction, is the electron distribution function, C is the collision operator, < > is the bounce average value, D LH and D HHFWis the corresponding RF quasi-linear diffusion coefficient, which can be calculated by the Kennel and Engelmann expressions; ; ; ; ; where is the parallel component of the wave vector, is the wave frequency, is the cyclotron frequency, J is the Bessel function, n is the harmonic number. Since both the HHFW and LH waves depend on electron Landau damping, take n = 0, 、 and are the components of the wave electric field; S4. The control variables respectively sweep the emission parameters of the LHW and HHFW scanning waves (wave frequency, emission position, emission angle, initial parallel refractive index), repeat S3, and calculate the current distribution respectively; S5. According to the current distribution results, add a current division module for different mechanisms in momentum space to the CQL3D program, describe different action mechanisms with adjoint functions, and calculate the momentum region corresponding to the synergistic effect to obtain the relevant physical parameters within the region; among them, the core of the current division module is the conservation equations constructed by semi-circular ring micro-elements and line integral micro-elements in momentum space:

[0007]

[0008]

[0009] ; where, f M is the initial Maxwell distribution function, f is the real-time evolution distribution function, p 1、 p2 are the initial and final state momenta of the selected micro-element respectively, r is the adjoint function, γ is the relativistic correction factor, ξ is the cosine value of the angle between the momentum and the magnetic field line, p ‖、 p ⊥ are the momentum components parallel and perpendicular to the magnetic field line respectively; After obtaining the cooperative momentum region and related parameters (cooperative momentum interval, peak integral current of different mechanisms, full width at half maximum, distribution interval), fit them with the radial distribution of the wave-driven current and the wave emission parameters (wave frequency, emission position, emission angle, initial parallel refractive index) when driven alone to form a function, and analyze their relationship; according to the target current peak, radial distribution range, and full width at half maximum of the current peak, feedback the parameter adjustment direction, and iterate repeatedly until the required localized current distribution is achieved, and select the parameter configuration plan with the largest cooperative factor and the highest driving efficiency; thus, the emission parameters of each frequency band of radio frequency waves obtained according to the adjustment principles of each radio frequency wave can ensure that the cooperative current has strong locality and high driving ability.

[0010] Preferably, the foregoing steps are for the localized control of the cooperative current distribution of LHW and HHFW that takes into account efficient driving.

[0011] Preferably, the parallel setting in S2 for handling abnormal situations or more optimized methods is specifically as follows: The lower hybrid wave has a higher current driving efficiency and can be used alone, or to prevent the loss of function due to insufficient current driving ability of the helicon wave. In the normalized minor radius range of 0.2 - 0.6, the locality of the LHW can be adjusted alone, and it can also take into account a relatively high driving efficiency and obtain a good localized current. The detailed scheme is as follows: A1. When the device conditions only allow emission on the low field side, select a poloidal emission angle of 60 degrees, which has the best locality. Under the consideration of other physical requirements and limitations, select the maximum initial parallel refractive index of the LHW that can be obtained, so that it is close to the parallel refractive index of strong Landau damping, and the condition for sufficient absorption of the lower hybrid wave electron Landau damping: >6.5 / Te 0.5 ; A2. If the device allows emission on the high field side, select a poloidal emission angle of 170 - 210 degrees to emit the LHW, which has the best locality effect. At the same time, under the consideration of other physical requirements and limitations, select the maximum initial parallel refractive index that can be obtained, which has the best effect; A3. Considering other physical requirements and limitations of the tokamak, within the allowable range, increase the toroidal field Bt to further improve the locality of the LHW-driven current distribution.

[0012] The beneficial effects of the present invention are as follows: (1) The cooperative control method for improving the locality of the radio frequency wave current drive in the tokamak realizes the cooperative control of the current drive advantages of radio frequency waves in different frequency bands, enhances the control ability of the overall current distribution, and brings beneficial effects to the improvement of the confinement performance of the plasma.

[0013] (2)The collaborative control method for enhancing the locality of tokamak radio-frequency wave current drive can ensure a high drive efficiency while taking into account the local control, bringing beneficial effects to the economic improvement of the fusion reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 For the embodiments of the present invention, (a) electron density distribution, (b) temperature distribution, (c) safety factor, and (d) wave trajectory diagrams of HHFW and LHW; Figure 2 Schematic diagram of the collaborative current drive momentum space collaborative mechanism between LHW and HHFW for the embodiments of the present invention; Figure 3 Schematic diagram of the power deposition and current radial distribution of the collaborative current drive between LHW and HHFW for the embodiments of the present invention; Figure 4 For the embodiments of the present invention, (a), (b), (c), (d), collaborative current and collaborative factor of HHFW and LHW and and schematic diagram of the relationship; Figure 5 Schematic diagram of the comparison of the locality of the drive current distribution when the parallel refractive index distribution is selected as 1.95 and 2.75 under the emission conditions on the low field side (upper) and high field side (lower) for the embodiments of the present invention; Figure 6 Schematic diagram of the comparison of the locality effects of LHW emission on the low field side and high field side for the embodiments of the present invention; Figure 7 Schematic diagram of the variation of the lower hybrid wave drive current with the normalized minor radius under different toroidal magnetic fields on the high field side for the embodiments of the present invention; Figure 8 Schematic diagram of the toroidal cross-section wave trace and the variation of the parallel refractive index with the increase of the toroidal magnetic field for the embodiments of the present invention; Figure 9 Schematic diagram of the steps of the collaborative control method for current drive and current distribution shown in the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0016] The embodiments of the present invention provide a technical solution: Refer to Figure 9, A collaborative control method for enhancing the locality of radio frequency wave current drive in a tokamak, including a collaborative control method for current drive and current distribution, specifically including the following steps: S1. According to the radial position where locality needs to be enhanced, use ECRH to heat the electrons in the narrow resonance layer at the corresponding radial position; S2. Adjust ICRH for regional heating, improve the ion and electron temperatures, which is beneficial to enhancing the locality of ICW, LHW, and HHFW. Try to make the radial position of the current peak of ICCD coincide with the radial position of the current peak of ECRH; S3. LHW and HHFW are driven collaboratively. Given a low hybrid wave frequency, select a helicon wave with an appropriate frequency; or given a helicon wave frequency, select a low hybrid wave with an appropriate frequency. The specific implementation method is as follows: First, given the initial frequencies of the two waves. Generally, combined with the device conditions, select a similar HHFW frequency according to the fixed LHW frequency; or fix the HHFW frequency and select a similar LHW frequency. Substitute them into the ray tracing and Fokker - Planck equations respectively, and use the simulation software package GENRAY / CQL3D to calculate the collaborative drive current of HHFW + LHW. The GENRAY program is used to track the dynamic evolution process of the wave trajectory, and the CQL3D program is used to calculate the solution of the electron distribution function in the two - dimensional momentum space of the Fokker - Planck equation. The key is to successfully add the quasilinear wave diffusion terms of LHW + HHFW and the contribution terms of the two waves into the Fokker - Planck equation to establish a collaborative drive model. The Fokker - Planck equation used in the simulation is as follows: ; In the formula, u represents the normalized electron momentum, , The subscript , denotes parallel and perpendicular, referring to the magnetic field direction, is the electron distribution function, C is the collision operator, < > is the bounce average value, D LH and D HHFW are the corresponding RF quasilinear diffusion coefficients, which can be calculated through the Kennel and Engelmann expressions; ; ; ; ; Among them is the parallel component of the wave vector, is the wave frequency, is the cyclotron frequency, J is the Bessel function, n is the harmonic number. Since both the HHFW and LH waves depend on the electron Landau damping, take n = 0, 、 and are the components of the wave electric field; S4. Respectively scan the emission parameters of the LHW and HHFW scanning waves (wave frequency, emission position, emission angle, initial parallel refractive index) for the control variables, repeat S3, and calculate the current distribution respectively; S5. According to the current distribution results, add a current division module for different mechanisms in the momentum space in the CQL3D program, describe different action mechanisms with adjoint functions, and calculate the momentum region corresponding to the synergistic effect to obtain the relevant physical parameters within the region; among them, the core of the current division module is the conservation equation group constructed by semi-circular ring micro-elements and line integral micro-elements in the momentum space:

[0017]

[0018]

[0019] ; wherein, f M is the initial Maxwell distribution function, f is the real-time evolution distribution function, p 1、 and p2 are the initial and final state momenta of the selected micro-element respectively, r is the adjoint function, γ is the relativistic correction factor, ξ is the cosine value of the angle between the momentum and the magnetic field line, p ‖、 p ⊥ are the momentum components parallel and perpendicular to the magnetic field line respectively.

[0020] After solving the synergistic momentum region and related parameters (synergistic momentum interval, integral current peak values of different mechanisms, full width at half maximum, distribution interval), fit them with the radial distributions of the different wave-driven currents and the wave emission parameters (wave frequency, emission position, emission angle, initial parallel refractive index) during single drive to form a function and analyze their relationship; according to the target current peak value, radial distribution range, and full width at half maximum of the current peak, feedback the parameter adjustment direction, and iterate repeatedly until the required localized current distribution is achieved, and select the parameter configuration scheme with the largest synergistic factor and the highest driving efficiency; thus far, the emission parameters of each frequency band of radio frequency waves obtained according to the adjustment principle of each radio frequency wave can ensure that the synergistic current has strong locality and high driving ability; In the present invention, the foregoing steps are for the local control of the synergistic current distribution of the LHW and HHFW while taking into account efficient driving.

[0021] In the present invention, the specific method of arranging in parallel in S2 for handling abnormal situations or more optimized ways is as follows: The lower hybrid wave has a high current drive efficiency and can be used alone, or to prevent the loss of function due to insufficient current drive ability of the helicon wave. In the normalized minor radius range of 0.2 to 0.6, the locality of the LHW can be individually adjusted, and high drive efficiency can also be taken into account to obtain a good localized current. The detailed scheme is as follows: A1. When the device conditions only allow emission from the low field side, select a poloidal emission angle of 60 degrees, which has the best locality. Under the consideration of other physical requirements and limitations, select the maximum initial parallel refractive index of the LHW that can be obtained, so that it is close to the strong Landau damping parallel refractive index. The conditions for sufficient absorption of the lower hybrid wave electron Landau damping are: >6.5 / Te 0.5 ; A2. If the device allows emission from the high field side, select a poloidal emission angle of 170 - 210 degrees to emit the LHW, which has the best locality effect. At the same time, under the consideration of other physical requirements and limitations, select the maximum initial parallel refractive index that can be obtained, which has the best effect; A3. Considering other physical requirements and limitations of the tokamak, within the allowable range, increase the toroidal field Bt to further improve the locality of the LHW driven current distribution; Among them, for the general steps of steps S1 and S2, under normal conditions, the locality control of the collaborative current distribution of the LHW and HHFW that takes into account efficient drive is applicable in the normalized minor radius range from 0 to 1; Secondly, in special cases, when parallel designed to only adjust the normalized radius from 0.2 to 0.6 and only use the lower hybrid wave, there is no need to solve the collaborative equation step; Embodiment

[0022] Use the experimental diagnostic data of the #63982 EAST discharge to simulate the combined current drive of HHFW / LHW. The distributions of the electron temperature, density, and safety factor of shot 63982 at t = 5s are as shown in Figure 1 (a), (b), (c), and the magnetic equilibrium reconstructed by EFIT is as shown in Figure 1 (d). The central electron temperature , the central electron density , the toroidal magnetic field T, the effective charge number , the plasma current .

[0023] Emit the LHW with a frequency of 4.6 GHz from the midplane of the low field side. The parallel refractive index of the main peak of the power spectrum is 2.04

[35] , the initial spectral width =0.26. Assume the frequency is 1 GHz, The HHFW with = 1.9 is also launched from the midplane of the low-field side (LFS), and the toroidal launch angle of the LHW , the toroidal launch angle of the HHFW Figure 1 . The input power of each of the two waves is set to 1 MW, and 50 Gaussian rays in GENRAY are used to describe the wave propagation and damping. Figure 2 (d) shows the ray trajectories of the HHFW and LHW calculated by the GENRAY code with rays launched from five different poloidal positions, Figure 1 (d) and Figure 2 show the power deposition of the two waves.

[0024] The radial power absorption curves and driven current curves of the LHW, HHFW, and LHW+HHFW are shown in Figure 4 (a) and (b) respectively. The LHW can drive with a high efficiency of about 220 kA off-axis current, while the current drive efficiency of the HHFW is only 19 kA. The wave energy deposits energy near the plasma core. We find that the total current of the two-wave combined drive reaches 341 kA, which is significantly greater than the sum of the individual currents of the two waves driven separately. The synergistic current is defined as . For this example, . In addition, the synergistic effect is quantified by the synergistic factor, and the synergistic factor can be defined as ; in this example, the synergistic factor is 1.43. It can be seen that a positive synergistic effect appears at (only in the radial profile region of the LHWCD). For example, the current density at increases from to . At the same time, there is a negative synergistic effect in the region, and the current near the core driven only by the HHFW completely disappears. Under low discharge conditions, the combined HHFW / LHWCD can significantly improve the efficiency of RFCD, and at the same time, the current driven by the HHFW moves from the core to the off-axis region.

[0025] Another LHCD system with a frequency of 2.45 GHz is adopted in the simulation, and it is found that the synergistic effect still exists, but both the synergistic current and the synergistic factor decrease. The synergistic current , and the synergistic factor is 1.39. In our simulation of the combined CD, the wave frequencies and parallel refractive indices of LHW and HHFW were scanned, as Figure 4 shown in (a), (b), (c), and (d). Although the co-current and co-factor are slightly different, there is a widespread positive co-effect between different and LHW and HHFW. After implementing this scheme, the radial current distribution changes from the original 0.1 to 0.85 to 0.25 to 0.5, and the localization is enhanced. Example

[0026] A co-control method for enhancing the localization of radio frequency wave current drive in a tokamak. In this example, LHCD alone controls the localized current distribution. Please refer to Figure 5 , taking the parameters of the HL-2M device and the parameters related to the lower hybrid wave emission as the background, with a major radius of 1.78 m, a minor radius of 0.65 m, a plasma current of 0.8 - 1.5, 2.5 MA, an electron central density of 3 - 10×10^19 m^(-3), an electron central temperature of 5 - 10 keV, a lower hybrid wave emission frequency of 3.7 GHz, and a lower hybrid wave emission power of 1.0 MW. Emitting from the high field side, when the initial parallel refractive index is 1.95 and the plasma current is relatively small (0.8 MA, 0.9 MA), the lower hybrid wave current distribution is at the edge position of 0.7 to 0.9, and the distribution is relatively scattered with multiple peaks, and the localization is not strong. When the plasma current increases, the current localization is enhanced and moves towards the core. When the parallel refractive index increases to 2.15, this phenomenon becomes more obvious, and the current is closer to the core and the localization is stronger. When the plasma current is relatively small (0.8 MA, 0.9 MA), the driven current still does not have good localization. However, when the parallel refractive index (2.35 - 2.75) is increased for the driven current with a plasma current of 1.0 MA - 2.5 MA, it has stable and good localization. In this parallel refractive index range, when the plasma current is 1.3 - 1.5 MA, the driven current is the largest, the localization is the strongest, and the distribution is closest to the core. When the plasma current increases to 2.5 MA, the current peak decreases and the current distribution moves outward. Generally speaking, when emitting from the high field side, a larger parallel refractive index can obtain a driven current with a larger peak, stronger localization, and closer to the core.

[0027] In this example, due to the toroidal asymmetry of the tokamak, the magnetic field, density, temperature, and scrape-off layer conditions corresponding to different toroidal angles are different. The selection of the toroidal emission angle position is also very important for the lower hybrid wave current drive. The toroidal emission angle is scanned from 0 to 360 degrees to analyze the influence of emitting lower hybrid waves at different toroidal angles on the current distribution.

[0028] Refer to Figure 6, in this embodiment, when the poloidal emission angle is 0 degrees, the current peak is distributed at the plasma edge. As the poloidal emission angle increases, the driven current significantly moves towards the core, the edge peak gradually decreases, and the current distribution gradually broadens. When the poloidal emission angle θ increases to 60 degrees, a current distribution with better localization and closer to the core appears, especially when the plasma current is 1.0 - 1.5 MA. As the poloidal emission angle continues to increase, the current distribution continues to broaden. When θ is 70 - 110 degrees, the driven current distribution by the lower hybrid wave is extremely scattered, and the range almost covers the entire poloidal cross-section, with the maximum peak position close to the edge. As the poloidal angle emission angle continues to increase, from 110 to 130 degrees for θ, the current peak moves inwards, but the distribution is still very scattered and has poor localization. When θ increases to 140 - 160 degrees, the current distribution begins to show localization and is almost all distributed in the core (ρ = 0.1 - 0.5) region. When the poloidal angle increases to 170 degrees, a single peak with stronger localization begins to appear (when the plasma current is 2.5 MA). Although the driven current under the condition of plasma current from 0.9 - 1.5 MA does not form a single peak, it also has good localization. When θ is 180 - 210 degrees, the driven current reaches the strongest localization, and the current distribution position is close to the core. Among them, the smaller the plasma current value, the closer the current peak is to the core. When the plasma current increases to 2.5 MA, the driven current is lower, the peak is more towards the outside, but still has good localization, compared with a larger current peak. When the poloidal angle increases to 220 - 250 degrees, the driven current peak begins to move towards the edge, and multiple peaks appear. When the poloidal angle is 260 - 270 degrees, the driven current distribution completely moves to the outer half region (ρ = 0.5 - 1). When θ turns back to the low field side, at 280 - 300 degrees, the driven current at the edge begins to move towards the core, and the current distribution becomes more dispersed. When θ is 260 - 300 degrees, the driving effect is poor, and the actual position is already at the bottom of the tokamak. When θ = 310, a current peak with slightly improved localization appears near ρ = 0.5. When θ increases to 320 - 330 degrees, a current distribution with a larger peak and stronger localization can still be generated in the core under the condition of lower plasma current, but in the case of larger plasma current (2.5 MA), the current distribution broadens and flattens, and a small peak appears at the edge. As θ continues to increase, to 340 - 350 degrees, the current broadens. As the plasma current increases, the core current flattens and the edge current rises.

[0029] Compared with the low-field side, the tokamak has a higher magnetic field and a stationary scrape-off layer on the high-field side. These conditions are conducive to lower hybrid current drive and can achieve better current drive effects. However, good current drive and control effects do not occur at all positions on the high-field side. From the above simulation scans and research analyses, it can be seen that the range of the poloidal emission angle with the best local control is approximately between 170° and 210°. In this poloidal emission angle range, the driven current of the lower hybrid wave has strong locality, a large peak value, and is close to the core.

[0030] See Figure 7 , in this embodiment, with the increase of the toroidal magnetic field, it is obvious that the current distribution moves towards the center, the peak value increases, and for the same toroidal magnetic field, when the plasma current increases, the change in the radial distribution range and the radial movement are very small, and the current distribution always shows a narrow single peak and maintains good locality; In this embodiment, see Figure 8 , and on the high-field side, after the lower hybrid wave is launched, it propagates downward in the lower plane, starts to rotate upward after a short path, reaches the core, and is absorbed once. Unlike the situation on the low-field side, the wave trace rotates around the poloidal plane for nearly one week or even longer. For example, in the case of Ip = 1MA and Bt = 2T, the lower hybrid wave is emitted from the high-field side and first propagates downward along a relatively straight path, undergoes refraction, rotates downward and then rises rapidly, with a relatively small rotation radius, and reaches a position near the core and is damped and absorbed. When Bt = 2.25T, the basic movement of the wave trace is basically the same as that when Bt = 2T, but the rotation radius of the wave trace is even smaller, and it is absorbed more quickly, and the damping position is closer to the core. When Bt = 2.5T, when the wave trace propagates near the core, the rotation radius is even smaller, and there is a secondary refraction of the wave trace. Looking at the results of the parallel refractive index, it is exactly the situation of being strongly damped twice, but finally it is absorbed at similar radial positions. From the results of the wave trace, it can also be seen that for the case of emission from the high-field side, as Bt increases, it is more conducive to the lower hybrid wave entering the core, and the neat and unified wave traces concentrated in the lower plane are another manifestation of locality.

[0031] In this embodiment, from the results of the refractive index change, it can also be seen that on the high-field side, and with the increase of the longitudinal field, the position where strong Landau damping occurs is deeper (140cm, 150cm, 250cm), which makes the current distribution move towards a position closer to the core. In the case of Bt = 2.5T, at 145cm, relatively strong damping also occurs, which is also one of the reasons for the increase in current.

[0032] In summary, in the case of the increase of the longitudinal field, the lower hybrid wave-driven current on the high-field side can still maintain good locality, and the distribution is closer to the core and the peak value is also larger.

[0033] The key point of this patented technology lies in making use of the advantages of each radio frequency band in current drive and current distribution control; making use of: 1. the localization of electron cyclotron waves; making use of the property that ion cyclotron waves can directly heat ions and electrons in the core and related regions; making use of the characteristics of high harmonic fast waves without density limit and the high efficiency of core heating and current drive; making use of the high efficiency of lower hybrid current drive, and making use of the advantage of launching lower hybrid waves on the high field side), a new control scheme with strong universality and feasibility for radio frequency wave collaborative control has been explored (it should be specifically noted that the "collaborative control" here includes not only the control of the injection sequence, emission position, power deposition, etc. of different radio frequency waves, but also the joint control of simultaneously injected lower hybrid waves and high harmonic fast waves). On the premise of taking into account a relatively high current drive efficiency, a stronger localized current profile can still be obtained, and the current distribution can be better controlled.

[0034] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation.

[0035] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A coordinated control method for improving the localization of radio frequency wave current drive in a Tokamak, including a coordinated control method for current drive and current distribution, characterized in that: The specific steps include: S1, according to the radial position where the localization needs to be enhanced, the electrons in the narrow resonance layer at the corresponding radial position are heated by ECRH; S2. Adjust ICRH for regional heating to increase the temperature of ions and electrons, which is beneficial to improve the localization of ICW (ion cyclotron wave), LHW and HHFW, and try to make the radial position of the current peak of ICCD (ion cyclotron current drive) coincide with the radial position of the current peak of ECRH; S3, LHW and HHFW are driven in coordination, and a spiral wave of appropriate frequency is selected when the low hybrid wave frequency is given; or a low hybrid wave of appropriate frequency is selected when the spiral wave frequency is given. The specific implementation method is as follows: First, the initial frequency of the dual waves is given. Generally, according to the fixed LHW frequency, a similar HHFW frequency is selected in combination with the device conditions; or a similar LHW frequency is selected with a fixed HHFW frequency, and the ray tracing and Fokker-Planck equation are substituted respectively. The simulation software package GENRAY / CQL3D is used to calculate the cooperative driving current of HHFW+LHW. The GENRAY program is used to track the dynamic evolution of the wave trajectory, and the CQL3D program is used to calculate the solution of the electron distribution function in the two-dimensional momentum space of the Fokker-Planck equation. The LHW+HHFW quasi-linear wave diffusion term, the contribution term of the two waves, is successfully added to the Fokker-Planck equation to establish a cooperative driving model. The Fokker-Planck equation used in the simulation is as follows: ； Where u represents the normalized electron momentum, , Subscript , Indicates parallel and perpendicular, referring to the direction of the magnetic field, is the electron distribution function, C is the collision operator, < > is the rebound average, D LH and D HHFW is the corresponding RF quasi-linear diffusion coefficient, which can be calculated using the Kennel and Engelmann expressions; ； ; ; ; in is the parallel component of the wave vector, is the wave frequency, is the cyclotron frequency, J is the Bessel function, and n is the harmonic number. Since both HHFW and LH waves depend on electron Landau damping, n=0 is taken. , and is the component of the wave’s electric field; S4, control variables to scan the LHW and HHFW scanning wave emission parameters (wave frequency, emission position, emission angle, initial parallel refractive index), repeat S3, and calculate the current distribution respectively; S5. According to the current distribution results, the current partitioning module with different mechanisms in momentum space is added to the CQL3D program. The different action mechanisms are described by accompanying functions, and the momentum region corresponding to the synergistic effect is calculated to obtain the relevant physical parameters in the region. Among them, the core of the current partitioning module is the conservation equations constructed with semicircular ring microelement and line integral microelement in momentum space: ； Among them, f M is the initial Maxwell distribution function, f is the real-time evolution distribution function, p 1、 p2 are the initial and final state momentum of the selected microelement, r is the adjoint function, γ is the relativistic correction factor, ξ is the cosine value of the angle between momentum and magnetic field lines, p ‖、 p ⊥ are the momentum components parallel and perpendicular to the magnetic field lines respectively; After solving the synergistic momentum area and related parameters (synergistic momentum interval, integrated current peak values ​​of different mechanisms, half-width, distribution interval), fit them with the radial distribution of different wave driving currents when driven alone and the wave emission parameters (wave frequency, emission position, emission angle, initial parallel refractive index) to form a function, and analyze their relationship; according to the target current peak value, radial distribution range and half-width of the current peak, the feedback parameter adjusts the direction, and iterates repeatedly until the required localized current distribution is achieved, and selects the parameter configuration scheme with the largest synergistic factor and the highest driving efficiency; at this point, the emission parameters of the radio frequency waves in each frequency band obtained according to the principle of adjusting each radio frequency wave can ensure that the synergistic current has strong localization and efficient driving capability.

2. The method for cooperative control of improving the locality of radio frequency wave current drive in Tokamak according to claim 1, characterized in that: The aforementioned steps are to realize the regional control of the coordinated current distribution of LHW and HHFW with consideration of efficient driving.

3. The method for cooperative control of improving the locality of the radio frequency wave current drive of a Tokamak according to claim 2 is characterized in that: The parallel setting in S2 is used to handle abnormal situations or a more optimized method. The low hybrid wave has a higher current driving efficiency and can be used alone, or to prevent the spiral wave from losing its function due to insufficient current driving ability. The locality of the LHW can be adjusted independently within the normalized small radius range of 0.2 to 0.6, which can also take into account higher driving efficiency and obtain good local current. The detailed scheme is as follows: A1. When the device condition only allows emission on the low field side, a polar emission angle of 60 degrees is selected, which is the best localization. Taking into account other physical requirements and restrictions, the maximum obtainable LHW initial parallel refractive index is selected to make it close to the strong Landau damping parallel refractive index. The low hybrid wave electron Landau damping fully absorbs the conditions: >6.5 / Te 0.5 ; A2. If the device allows high-field side emission, select the polar emission angle of 170 to 210 degrees to emit LHW, which has the best local effect. At the same time, taking into account other physical requirements and limitations, select the maximum initial parallel refractive index that can be obtained, which has the best effect. A3. Taking into account other physical requirements and limitations of the Tokamak, within the allowable range, enhancing the longitudinal field Bt further improves the locality of the LHW drive current distribution.

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