scholarly journals Control of magnetohydrodynamic stability by phase space engineering of energetic ions in tokamak plasmas

2012 ◽  
Vol 3 (1) ◽  
Author(s):  
J.P. Graves ◽  
I.T. Chapman ◽  
S. Coda ◽  
M. Lennholm ◽  
M. Albergante ◽  
...  
Keyword(s):  
Phase Space ◽  
Tokamak Plasmas ◽  
Energetic Ions

Second stable regime of internal kink modes excited by barely passing energetic ions in tokamak plasmas

2010 ◽  
Vol 17 (8) ◽  
pp. 082512 ◽  
Author(s):  
H. D. He ◽  
J. Q. Dong ◽  
G. Y. Fu ◽  
G. Y. Zheng ◽  
Z. M. Sheng ◽  
...  
Keyword(s):  
Tokamak Plasmas ◽  
Energetic Ions ◽  
Stable Regime

Double fishbone instability excited by energetic ions with m = n = 1 in a reversed magnetic shear tokamak plasmas

2015 ◽  
Vol 22 (9) ◽  
pp. 092510 ◽  
Author(s):  
Guo Meng ◽  
Xian-Qu Wang ◽  
Xiaogang Wang ◽  
Rui-Bin Zhang
Keyword(s):  
Tokamak Plasmas ◽  
Magnetic Shear ◽  
Energetic Ions

Simulation study of energetic-particle driven off-axis fishbone instabilities in tokamak plasmas

2021 ◽  
Author(s):  
Hanzheng Li ◽  
Y Todo ◽  
Hao Wang ◽  
Malik Idouakass ◽  
Jialei Wang
Keyword(s):  
Distribution Function ◽  
Resonance Frequency ◽  
Linear Growth ◽  
Particle Interaction ◽  
Primary Resonance ◽  
Tokamak Plasmas ◽  
Spatial Profile ◽  
Energetic Ions ◽  
Nonlinear Phase ◽  
Drift Frequency

Abstract Kinetic-magnetohydrodynamic hybrid simulations were performed to investigate the linear growth and the nonlinear evolution of off-axis fishbone mode (OFM) destabilized by trapped energetic ions in tokamak plasmas. The spatial profile of OFM is mainly composed of m/n = 2/1 mode inside the q = 2 magnetic flux surface while the m/n = 3/1 mode is predominant outside the q = 2 surface, where m and n are the poloidal and toroidal mode numbers, respectively, and q is the safety factor. The spatial profile of the OFM is a strongly shearing shape on the poloidal plane, suggesting the nonperturbative effect of the interaction with energetic ions. The frequency of the OFM in the linear growth phase is in good agreement with the precession drift frequency of trapped energetic ions, and the frequency chirps down in the nonlinear phase. Two types of resonance conditions between trapped energetic ions and OFM are found. For the first type of resonance, the precession drift frequency matches the OFM frequency, while for the second type, the sum of the precession drift frequency and the bounce frequency matches the OFM frequency. The first type of resonance is the primary resonance for the destabilization of OFM. The resonance frequency which is defined based on precession drift frequency and bounce frequency of the nonlinear orbit for each resonant particle is analyzed to understand the frequency chirping. The resonance frequency of the particles that transfer energy to the OFM chirps down, which may result in the chirping down of the OFM frequency. A detailed analysis of the energetic ion distribution function in phase space shows that the gradient of the distribution function along the E′ = const. line drives or stabilizes the instability, where E′ is a combination of energy and toroidal canonical momentum and conserved during the wave-particle interaction. The distribution function is flattened along the E′ = const. line in the nonlinear phase leading to the saturation of the instability.

scholarly journals High frequency fishbone driven by passing energetic ions in tokamak plasmas

2017 ◽  
Vol 57 (5) ◽  
pp. 056013
Author(s):  
Feng Wang ◽  
L.M. Yu ◽  
G.Y. Fu ◽  
Wei Shen
Keyword(s):  
High Frequency ◽  
Tokamak Plasmas ◽  
Energetic Ions

scholarly journals Simulation of convective transport during frequency chirping of a TAE using the MEGA code

2022 ◽  
Author(s):  
Hooman Hezaveh Hesar Maskan ◽  
Y Todo ◽  
Zhisong Qu ◽  
Boris N Breizman ◽  
Matthew J Hole
Keyword(s):  
Phase Space ◽  
Coarse Graining ◽  
Travelling Wave ◽  
Convective Transport ◽  
Space Structures ◽  
Tokamak Plasmas ◽  
Linear Evolution ◽  
Damping Rate ◽  
Space Dynamics ◽  
Frequency Chirping

Abstract We present a procedure to examine energetic particle phase-space during long range frequency chirping phenomena in tokamak plasmas. To apply the proposed method, we have performed self-consistent simulations using the MEGA code and analyzed the simulation data. We demonstrate a travelling wave in phase-space and that there exist specific slices of phase-space on which the resonant particles lie throughout the wave evolution. For non-linear evolution of an n=6 toroidicity-induced Alfven eigenmode (TAE), our results reveal the formation of coherent phase-space structures (holes/clumps) after coarse-graining of the distribution function. These structures cause a convective transport in phase-space which implies a radial drift of the resonant particles. We also demonstrate that the rate of frequency chirping increases with the TAE damping rate. Our observations of the TAE behaviour and the corresponding phase-space dynamics are consistent with the Berk-Breizman (BB) theory.

Theoretical studies of low-frequency Alfvén modes in tokamak plasmas

2021 ◽  
Author(s):  
R R Ma ◽  
Liu Chen ◽  
Fulvio Zonca ◽  
Yueyan Li ◽  
Zhiyong Qiu
Keyword(s):  
Low Frequency ◽  
Acoustic Mode ◽  
Frequency Region ◽  
Physical Parameters ◽  
Linear Wave ◽  
Tokamak Plasmas ◽  
High Frequency Region ◽  
Energetic Ions ◽  
Ballooning Mode ◽  
Spectral Patterns

Abstract Linear wave properties of the low-frequency Alfvén modes (LFAMs) observed in the DIII-D tokamak experiments with reversed magnetic shear [Nucl. Fusion 61, 016029 (2021)] are theoretically studied and delineated based on the general fishbone-like dispersion relation. By adopting the representative experimental equilibrium parameters, it is found that, in the absence of energetic ions, the LFAM is a kinetic ballooning mode instability of reactive-type with a dominant Alfvénic polarization. More specifically, due to diamagnetic and trapped particle effects, the LFAM can be coupled with the beta-induced Alfvén-acoustic mode in the low-frequency region (frequency much less than the thermal-ion transit and/or bounce frequency); or with the beta-induced Alfvén eigenmode in the high frequency region (frequency higher than or comparable to the thermal-ion transit frequency); resulting in reactive-type instabilities. Moreover, the ‘Christmas light’ and ‘mountain peak’ spectral patterns of LFAMs as well as the dependence of instability drive on the electron temperature observed in the experiments can be theoretically interpreted by varying the relevant physical parameters. Conditions when dissipative-type instabilities may set in are also discussed.

Simulation of toroidicity-induced Alfven eigenmode excited by energetic ions in HL-2A tokamak plasmas

2018 ◽  
Vol 58 (12) ◽  
pp. 126023
Author(s):  
Hongda He ◽  
Junyi Cheng ◽  
J.Q. Dong ◽  
Wenlu Zhang ◽  
Chenxi Zhang ◽  
...  
Keyword(s):  
Tokamak Plasmas ◽  
Energetic Ions

scholarly journals The spontaneous destabilization of neoclassical tearing mode with existing energetic ions in low torque tokamak plasmas

2017 ◽  
Vol 57 (11) ◽  
pp. 114005
Author(s):  
Erzhong Li ◽  
L. Hu ◽  
H. Zhao ◽  
T. Shi ◽  
Y. Liu ◽  
...  
Keyword(s):  
Tokamak Plasmas ◽  
Tearing Mode ◽  
Energetic Ions ◽  
Low Torque ◽  
Neoclassical Tearing Mode

Interaction between energetic-ions and internal kink modes in a weak shear tokamak plasma

2021 ◽  
Author(s):  
Xiaolong Zhu ◽  
Feng Wang ◽  
Wei Chen ◽  
Zhengxiong Wang
Keyword(s):  
Nonlinear Dynamics ◽  
Resonance Condition ◽  
Particle Interaction ◽  
Critical Value ◽  
Mode Frequency ◽  
Tokamak Plasma ◽  
Tokamak Plasmas ◽  
Energetic Ions ◽  
Kink Mode ◽  
Reversed Shear

Abstract Based on the conventional tokamak HL-2A-like parameters and profiles, the linear properties and the nonlinear dynamics of non-resonant kink mode (NRK) and non-resonant fishbone instability (NRFB) in reversed shear tokamak plasmas are investigated by using the global hybrid kinetic-magnetohydrodynamic (MHD) nonlinear code M3D-K. This work mainly focuses on the effect of passing energetic-ions on the NRK and NRFB instabilities, which is different from the previous works. It is demonstrated that the NRFB can be destabilized by the passing energetic-ions when the energetic-ion beta $\beta_h$ exceeds a critical value. The transition from NRK to NRFB occurs when the energetic-ion beta $\beta_h$ increases to above a critical value. The resonance condition responsible for the excitation of NRFB is interestingly found to be satisfied at $\omega_t+\omega_p\approx\omega$, where $\omega_t$ is the toroidal motion frequency, $\omega_p$ is the poloidal motion frequency and $\omega$ is the mode frequency. The nonlinear evolutions of NRFB's mode structures and Poincar\'{e} plots are also analyzed in this work and it is found that the NRFB can induce evident energetic-ion loss/redistribution, which can degrade the performance of the plasmas. These findings are conducive to understanding the mechanisms of NRFB-induced energetic-ion loss/redistribution through nonlinear wave-particle interaction.

scholarly journals 3D field phase-space control in tokamak plasmas

2018 ◽  
Vol 14 (12) ◽  
pp. 1223-1228 ◽  
Author(s):  
Jong-Kyu Park ◽  
YoungMu Jeon ◽  
Yongkyoon In ◽  
Joon-Wook Ahn ◽  
Raffi Nazikian ◽  
...  
Keyword(s):  
Phase Space ◽  
Tokamak Plasmas ◽  
Field Phase
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