摘要：
Collisionless damping of the geodesic acoustic mode due to electron dynamics in rotating tokamak plasmas is investigated. A dispersion relation of the geodesic acoustic mode with a non-adiabatic electron response in a rotating tokamak is derived and solved both analytically and numerically. It is found that the collisionless damping of the geodesic acoustic mode, due to electron dynamics, significantly increases with the increasing toroidal rotation, especially in the large safety factor regime. The rotation-induced frequency up-shift of the geodesic acoustic mode increases the resonant velocity, which enables a larger number of electrons to resonate with the geodesic acoustic mode. The significant increase of the number of the resonant electrons significantly enhances the collisionless damping of the geodesic acoustic mode. The result indicates that in rotating tokamak plasmas a more complete picture of the geodesic acoustic mode should include the electron dynamics.
期刊：
PHYSICS OF PLASMAS,2016年23(1):012301 ISSN：1070-664X
通讯作者：
Cao, Jinjia
作者机构：
[Xiang, Dong; Huang, Qianhong; Gong, Xueyu; Cao, Jinjia] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Wang, Aike] Southwestern Inst Phys, POB 432, Chengdu 610041, Peoples R China.;[Yu, Jun] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Cao, Jinjia] U;Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.
关键词：
plasma collision processes;plasma flow;plasma kinetic theory;plasma transport processes
摘要：
The enhanced transport of passing energetic ions (PEIs) in presence of the resonant interactions with a rotating magnetic island is investigated within the drift kinetic framework. When the island rotation plays a role in the resonant interaction, we find that the velocities of PEIs satisfy a constraint relation of resonant flux surface in phase space. The resonant flux surfaces overlap with the magnetic flux surfaces in real space. A new transport channel responsible for the PEIs moving across the magnetic flux surfaces, i.e., continuously overlapping, is found. Two kinds of radial motions can be induced by the surface overlapping: one arises from the coupling between the resonance and the collision with the background plasma and the other from not completely overlapping of the two surfaces. The two radial motions and the symmetry-breaking induced radial motion constitute the total radial motion. When the pitch-angle scattering rate is very weak, the surface-shear induced transport is dominant. Only a small increase in the collision rate can significantly influence the total transport.
作者：
Cao, Jinjia;Gong, Xueyu*;Xiang, Dong;Huang, Qianhong;Yu, Jun
期刊：
PHYSICS OF PLASMAS,2016年23(8):082301 ISSN：1070-664X
通讯作者：
Gong, Xueyu
作者机构：
[Xiang, Dong; Huang, Qianhong; Gong, Xueyu; Cao, Jinjia] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Yu, Jun] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Gong, Xueyu] U;Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.
关键词：
plasma interactions;plasma transport processes
摘要：
The structure of the drift-island surface of passing fast ions (PFIs) is investigated in the presence of the resonant interaction with a magnetic island. Two overlapping regions of the drift-island surface and the magnetic island surface are found, one corresponding to local overlapping region and the other to non-local one. Here, the word “nonlocal” denotes that the resonances in the core plasma can have effects on the PFIs near the plasma boundary, while the “local” represents that the PFIs just near the resonant location are influenced. The nonlocal overlapping constructs a transport path along which the PFIs can become losses. There are three kinds of drift-island surfaces to join in forming the transport paths. A pitch angle region, which is called pitch angle gap, is found near the plasma boundary, where the drift-island surface cannot be formed and few PFIs are lost. The pitch-angle selective features of PFI losses are obtained by analyzing the three kinds of drift-island surfaces. The coupling between the crowd drift island surfaces and the collision can induce the prompt losses of PFIs and rapidly slowing down of PFI energy. The time of the prompt losses and the slowing down rate are calculated. Qualitatively, the theoretical results are in well agreement with the experimental observations in ASDEX Upgrade [M. García-Muñoz et al., Nucl. Fusion 47, L10 (2007)].
摘要：
With the dispersion relation derived for the geodesic acoustic mode in toroidally rotating tokamak plasmas using the fluid model, the effect of the toroidal rotation on the collisional viscous damping of the geodesic acoustic mode is investigated. It is found that the collisional viscous damping of the geodesic acoustic mode has weak increase with respect to the toroidal Mach number.
摘要：
The collisional damping of the geodesic acoustic mode (GAM) is analytically investigated in toroidally rotating tokamaks by using the gyrokinetic equation. It is found that the toroidal rotation could decrease the collisional damping of the GAM in the small safety factor region and increase the collisional damping of the GAM in the large safety factor region at low ion collision rate; while at high ion collision rate, the toroidal rotation will increase the collisional damping of the GAM with arbitrary safety factor. Furthermore, the change quantity of collisional damping rate of the GAM due to the toroidal rotation at high collision rate is larger than that at low collision rate.
作者机构：
[Chen, You; Gong, Xueyu; Yu, Jun] Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.;[Gong, Xueyu] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Hunan, Peoples R China.
通讯机构：
[Yu, Jun] U;Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.
关键词：
tokamak plasma;zonal flow;turbulence
摘要：
With the nonlinear dispersion relation derived, excitation of low frequency zonal flow by drift waves is examined in tokamak plasmas with toroidal rotation. It is shown that the growth rate of the low frequency zonal flow is decreased by the frequency shift of the geodesic acoustic mode and is increased by the additional nonlinear terms with toroidal rotation velocity. If the amplitude of the pump drift wave is greater than the threshold value, which is the function of the Mach number of the toroidal rotation, the toroidal rotation increases the nonlinear growth rate, otherwise, it decreases the nonlinear growth rate. There is always a finite nonlinear growth rate of the low frequency zonal flow if only there is a finite amplitude of the pump wave in tokamak plasmas with a finite velocity of the toroidal rotation.
作者机构：
[余江妹; 谢宝艺; 张能] School of Mathematics and Physics, University of South China, Hengyang, 421001, China;[龚学余] School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China
摘要：
A three dimensional bounce-averaged Fokker-Planck (FP) numerical code has been newly developed based on fully implicit iterative solving method, and relativistic effect is also included in the code. The code has been tested against various benchmark cases: Ohmic conductivity in the presence of weak Ohmic electric field, runaway losses of electrons in the presence of strong Ohmic electric field, lower hybrid current drive and electron cyclotron current drive via two- or three-dimensional simulation. All the test cases run fast and correctly during calculations. As a result, the code provides a set of powerful tools for studying radio frequency wave heating and current drive in tokamak plasmas.
作者：
Yu, Jun*;Dong, J. Q.;Li, X. X.;Du, D.;Gong, X. Y.
期刊：
Journal of Plasma Physics,2012年78(6):651-655 ISSN：0022-3778
通讯作者：
Yu, Jun
作者机构：
[Du, D.; Yu, Jun] Univ S China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.;[Dong, J. Q.] Zhejiang Univ, Inst Fus Theory & Simulat, Dept Phys, Hangzhou 310027, Zhejiang, Peoples R China.;[Dong, J. Q.] SW Inst Phys, Chengdu, Peoples R China.;[Li, X. X.; Gong, X. Y.] Univ S China, Sch Nucl Sci & Technol, Hengyang 421001, Hunan, Peoples R China.
通讯机构：
[Yu, Jun] U;Univ S China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.
摘要：
Excitation of the geodesic acoustic mode continuum by drift wave turbulence is studied using the wave kinetic approach. For a model profile of weak non-uniform ion temperature, the forms of growth rate and radial structure of geodesic acoustic modes are obtained analytically. The growth rate is analyzed for several conditions for present-day tokamaks and compared with that for uniform ion temperature, as well as that given by the coherent mode approach for non-uniform ion temperature.
摘要：
Abstract: The growth rate of the geodesic acoustic mode and the radial structures of the sideband drift waves and the geodesic acoustic modes continuum are studied as a parametric process in the tokamak plasmas with a non-uniform ion temperature profile for which the non-uniform part of the inherent geodesic acoustic mode frequency takes the form of sin function. It is shown that the radial structures of the drift wave sideband are close to the harmonic function, the en- ergies of the geodesic acoustic modes are mainly localized around the resonant points of the parametric excitations, and the growth rate is proportional to the square of the amplitude of the pump wave, which indicates that the corresponding analytical results is reasonable.#@#@#摘要: 为了验证Yu和Dong给出的解析结果的合理性，用数值计算的方法对离子温度为非均匀的等离子体中测地声模连续谱的非线性激发过程进行了研究。数值计算的结果表明，漂移波边带模的径向结构分布图与简谐振荡都很接近，这说明Yu和Dong对参量激发方程的解析求解的出发点是合理的。对于一定的离子温度分布，在一定共振频率的条件下，测地声模连续谱的增长率与漂移波的振幅的平方成正比，这和Yu和Dong给出的相关的解析结果的结论一致。根据所求出的漂移波边带模的径向分布，可以计算出测地声模的径向结构分布。计算的结果表明，测地声模连续谱的振幅在共振点附近具有最大值。
作者：
Du, Dan*;Gong, Xueyu;Wang, Zhenhua;Yu, Jun;Zheng, Pingwei
期刊：
Journal of Plasma Physics,2012年78(6):595-599 ISSN：0022-3778
通讯作者：
Du, Dan
作者机构：
[Du, Dan; Yu, Jun] Univ S China, Dept Math & Phys, Hengyang City, Hunan, Peoples R China.;[Wang, Zhenhua; Gong, Xueyu] Univ S China, Dept Nucl Sci & Technol, Hengyang City, Hunan, Peoples R China.;[Zheng, Pingwei] Univ S China, Dept Environm Protect & Safety Engn, Hengyang City, Hunan, Peoples R China.
通讯机构：
[Du, Dan] U;Univ S China, Dept Math & Phys, Hengyang City, Hunan, Peoples R China.
摘要：
A well-optimized design of an ion cyclotron resonance heating (ICRH) antenna is very important for steady-state plasma heating with high radio frequency (RF) power of several tens of megawatts. However, a sharp decrease in the coupling RF power because of impedance mismatch of ICRH system is an issue that must be resolved for present-day fusion reactors and International Thermonuclear Experimental Reactor. This paper has theoretically analyzed the ICRH antenna's impedance matching for ELMy plasmas on experimental advanced superconducting tokamak (EAST) by the transmission line theory. The results indicate that judicious choice of the optimal feeder location is found useful for adjustable capacitors' tolerance to the variations of the antenna input impedance during edge-localized mode (ELM) discharge, which is expected to be good for the design of ICRH antenna system and for real-time feedback control during ELM discharge on EAST.
