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.

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.

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

scholarly journals Nonlinear Mirror and Weibel modes: peculiarities of quasi-linear dynamics

2010 ◽  
Vol 28 (12) ◽  
pp. 2161-2167 ◽  
Author(s):  
O. A. Pokhotelov ◽  
R. Z. Sagdeev ◽  
M. A. Balikhin ◽  
V. N. Fedun ◽  
G. I. Dudnikova
Keyword(s):  
Distribution Function ◽  
Mode Coupling ◽  
Nonlinear Evolution ◽  
Particle Interaction ◽  
Velocity Distribution Function ◽  
Larmor Radius ◽  
Initial Stage ◽  
Plasma State ◽  
Bgk Modes ◽  
Mirror Mode

Abstract. A theory for nonlinear evolution of the mirror modes near the instability threshold is developed. It is shown that during initial stage the major instability saturation is provided by the flattening of the velocity distribution function in the vicinity of small parallel ion velocities. The relaxation scenario in this case is accompanied by rapid attenuation of resonant particle interaction which is replaced by a weaker adiabatic interaction with mirror modes. The saturated plasma state can be considered as a magnetic counterpart to electrostatic BGK modes. After quasi-linear saturation a further nonlinear scenario is controlled by the mode coupling effects and nonlinear variation of the ion Larmor radius. Our analytical model is verified by relevant numerical simulations. Test particle and PIC simulations indeed show that it is a modification of distribution function at small parallel velocities that results in fading away of free energy driving the mirror mode. The similarity with resonant Weibel instability is discussed.

Solar coronal heating by Alfvén waves in bi-kappa distributed plasma

2019 ◽  
Vol 491 (2) ◽  
pp. 2403-2412 ◽  
Author(s):  
Imran A Khan ◽  
Z Iqbal ◽  
G Murtaza
Keyword(s):  
Distribution Function ◽  
Velocity Distribution ◽  
Particle Interaction ◽  
Velocity Distribution Function ◽  
Alfven Waves ◽  
Coronal Heating ◽  
Alfvén Waves ◽  
Heating Process ◽  
Thermal Features ◽  
Inertial Alfvén Waves

ABSTRACT In solar physics, there is a decades-old conundrum that is still unsolved. Why is the temperature of the corona so much larger than that of the surface of the Sun? To solve this, various approaches have been adopted so far, but they have certain limitations. In the present analysis, we invoke the standard Vlasov model and the steady-state Poynting theorem to unlock the mysterious coronal heating mechanism in terms of inertial and kinetic Alfvén waves whose electromagnetic energies turn into heat during wave–particle interaction. The coronal plasmas that support these waves are modelled by a non-thermal bi-kappa velocity distribution function. The non-thermal distribution function, which is assumed to pre-exist in the system, strongly influences the wave-heating process. Particularly, during heating by the waves in the inertial limit, the non-thermal features of the distribution function give rise to a unique competition (which is entirely absent in the usual Maxwellian plasmas) between waves of different perpendicular wavenumbers (kx). For small kx, when either the non-thermal parameter κ or the electron parallel temperature T||e increases, the inertial Alfvén waves can efficiently heat the plasma in their immediate vicinity. However, for relatively large kx, an increase in either κ or T||e enables the inertial Alfvén waves to effectively heat the plasma in remote regions in the corona. Although such competition is not seen in the kinetic limit, the non-thermal features still seem to control the heating process. The possible explanations behind the above-mentioned cases are provided by the bi-kappa velocity distribution function, which holds vital clues as to how the non-thermal features, together with kx, dictate the resonance conditions that play a crucial role in the heating process.

Nonlinear wave-particle interaction behaviors driven by energetic ions in the HL-2A Tokamak

2018 ◽  
Vol 58 (9) ◽  
pp. 096028 ◽  
Author(s):  
Y.M. Hou ◽  
W. Chen ◽  
Y. Yu ◽  
M. Lesur ◽  
X.R. Duan ◽  
...  
Keyword(s):  
Nonlinear Wave ◽  
Particle Interaction ◽  
Energetic Ions ◽  
Wave Particle Interaction ◽  
Interaction Behaviors

scholarly journals Resonance frequency broadening of wave-particle interaction in tokamaks due to Alfvénic eigenmode

2018 ◽  
Vol 58 (8) ◽  
pp. 082017 ◽  
Author(s):  
G. Meng ◽  
N.N. Gorelenkov ◽  
V.N. Duarte ◽  
H.L. Berk ◽  
R.B. White ◽  
...  
Keyword(s):  
Resonance Frequency ◽  
Particle Interaction ◽  
Wave Particle Interaction

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

scholarly journals Characteristics of precipitating energetic ions/electrons associated with the wave-particle interaction in the plasmaspheric plume

2012 ◽  
Vol 117 (A8) ◽  
pp. n/a-n/a ◽  
Author(s):  
Zhigang Yuan ◽  
Ying Xiong ◽  
Dedong Wang ◽  
Ming Li ◽  
Xiaohua Deng ◽  
...  
Keyword(s):  
Particle Interaction ◽  
Energetic Ions ◽  
Wave Particle Interaction

Longitudinal wave instability due to rotating beam-plasma interaction in weakly turbulent astrophysical plasmas

2019 ◽  
Vol 489 (3) ◽  
pp. 3059-3065
Author(s):  
S M Khorashadizadeh ◽  
Sh Abbasi Rostami ◽  
A R Niknam ◽  
S Vasheghani Farahani ◽  
R Fallah
Keyword(s):  
Distribution Function ◽  
Longitudinal Wave ◽  
Electron Distribution ◽  
Electron Distribution Function ◽  
Particle Interaction ◽  
Magnetoactive Plasma ◽  
Plasma Region ◽  
Wave Instability ◽  
Electrostatic Wave ◽  
Wave Particle Interaction

ABSTRACTThe aim of this study is to highlight the temporal evolution of the longitudinal wave instability due to the interaction between a rotating electron beam and the magnetoactive plasma region in space plasma structures. The plasma structure which could be either in the solar atmosphere or any active plasma region in space is considered weakly turbulent, where the quasi-linear theory is implemented to enable analytic insight on the wave–particle interaction in the course of the event. It is found that in a weakly turbulent plasma, quasi-linear saturation of the longitudinal wave is accompanied by a significant alteration in the distribution function in the resonant region. In case of a pure electrostatic wave, the wave amplitude experiences elevation due to the energy transfer from the plasma particles. This causes flattening of the bump on tail (BOT) in the electron distribution function. If the gradient of the distribution function is positive, the chance that the beam would excite the wave is probable. In such a situation a plateau on the distribution function (∂f/∂v ≈ 0) is formed that will stop the diffusion of beam particles in the velocity space. Evolution of the electron distribution function experiences a decreases of the instability of the longitudinal wave. It is deduced that the growth rate of the wave instability is inversely proportional to the wave energy. Regarding the Sun, in addition to creating micro-turbulence due to wave–particle interaction, as the wave elevates to higher altitudes it enters a saturated energy state before releasing energy that may be a candidate for the generation of radio bursts.

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