Dynamic evolution of resistive kink mode with electron diamagnetic drift in tokamaks

Zhang, W.; Zhang, Haowei; Zhu, Jia

doi:10.1063/1.5090226

Cited by 14 publications

(12 citation statements)

References 59 publications

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“…From a theoretical point of view, it is widely accepted that sawtooth oscillations are triggered by the instability of a resistive internal kink mode with mode numbers n = m = 1 and that the trigger conditions for the onset of this mode may be strongly affected by two-fluid effects such as electron and ion diamagnetism [29][30][31][32][33][34][35]. Weakly collisional or collisionless effects may also be important (see, e.g.…”

Section: Introductionmentioning

confidence: 99%

“…In order to focus on the nonlinear flow dynamics associated with the resistive internal kink mode, we have used the code CLT, whose features are discussed in more details in the next section. The CLT code was used in the past to study two-fluid and extended-MHD effects on the nonlinear magnetic reconnection dynamics [33,45]. In this article, where two-fluid and extended-MHD effects are beyond the scope of the present study, we shall perform viscosity scans at fixed electrical resistivity, with the viscosity coefficient varied by three orders of magnitude.…”

Section: Introductionmentioning

confidence: 99%

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Sawtooth relaxation oscillations, nonlinear helical flows and steady-state m/n=1 magnetic islands in low-viscosity tokamak plasma simulations

et al. 2020

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A numerical study on the influence of plasma viscosity and of the plasma (=kinetic pressure/magnetic pressure) parameter on the nonlinear evolution of resistive internal kink modes in tokamak plasmas is presented. A new regime with relatively low viscosity is found, such that sawtooth oscillations spontaneously evolve towards states with stationary m/n = 1 magnetic islands. It is suggested that the mechanism at work in the limit of small viscosity is related to magnetic flux pumping, which, allied with the nonlinear resistive internal kink dynamics, leads to a stationary helical flow, only weakly dissipated by viscosity and entirely self-consistent with the presence of saturated m/n = 1 stationary magnetic islands. It is also found that the threshold viscosity value for the onset of the steady-state regime increases with increasing values. The newly found regime for a steady-state m/n = 1 magnetic island may be relevant for the understanding of tokamak experiments, where saturated helical structures such as the density snake and steady-state magnetic islands are sometimes observed in the core plasma region where the safety factor is close to or below unity.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sawtooth relaxation oscillations, nonlinear helical flows and steady-state m/n=1 magnetic islands in low-viscosity tokamak plasma simulations

et al. 2020

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“…In this subsection, we numerically investigate the frequency evolution of the m/n=1/1 kink mode using three-dimensional, toroidal, and nonlinear Hall-MHD code CLT [41][42][43][44]. In dimensionless units, the equations used in CLT are given as follows:…”

Section: Simulation Resultsmentioning

confidence: 99%

Observations of mode frequency increase and the appearance of ITB during the m/n = 1/1 kink mode in EAST high electron temperature long pulse operation

Yan

Zhang

et al. 2023

Plasma Sci. Technol.

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A new long-pulse high electron temperature (T_e) regime has been achieved on Experimental Advanced Superconducting Tokamak (EAST) by pure Radio Frequency (RF) heating. In this new scenario, there are mainly two confinement states involving two Magneto-hydrodynamic (MHD) modes, one of which is identified as m/n=1/1 kink mode (where m and n are the poloidal and toroidal mode numbers, respectively). The frequency evolution of the kink mode is investigated through the three-dimensional, toroidal, and nonlinear Hall-MHD code CLT. We firstly find that the frequency of the m/n=1/1 kink mode significantly increases during each sawtooth crash and then confirm it through the experimental data. The simulation results indicate that the increase of the mode frequency is mainly due to the significant increase of the electron diamagnetic frequency nearby the reconnection region. We have also observed the internal transport barrier (ITB) during the m/n=1/1 kink mode. To further investigate this m/n=1/1 kink mode in this new regime, the multi-scale interactions between the m/n=1/1 kink mode and turbulence are discussed.

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“…The effectiveness of these codes has been demonstrated, and many physical problems were studied by using these codes. [34][35][36][37][38][39] Hence, the applications of spectral methods are noteworthy in MHD simulations of tearing mode instability. However, it seems that spectral methods are not used as the discrete form individually.…”

Section: Introductionmentioning

confidence: 99%

Application of Galerkin spectral method for tearing mode instability

Sun

Wang²,

Wei³

et al. 2022

Chinese Phys. B

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Magnetic reconnection and tearing mode instability play a critical role in many physical processes. The application of Galerkin spectral method for tearing mode instability in two-dimensional geometry is investigated in this paper. A resistive magnetohydrodynamic code is developed, by the Galerkin spectral method both in the periodic and aperiodic directions. Spectral schemes are provided for global modes and local modes. Mode structures, resistivity scaling, convergence and stability of tearing modes are discussed. The effectiveness of the code is demonstrated, and the computational results are compared with the results of using Galerkin spectral method only in the periodic direction. The numerical results show that the code using Galerkin spectral method individually allows larger time step in global and local modes simulations, and has better convergence in global modes simulations.

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Dynamic evolution of resistive kink mode with electron diamagnetic drift in tokamaks

Cited by 14 publications

References 59 publications

Sawtooth relaxation oscillations, nonlinear helical flows and steady-state m/n=1 magnetic islands in low-viscosity tokamak plasma simulations

Sawtooth relaxation oscillations, nonlinear helical flows and steady-state m/n=1 magnetic islands in low-viscosity tokamak plasma simulations

Observations of mode frequency increase and the appearance of ITB during the m/n = 1/1 kink mode in EAST high electron temperature long pulse operation

Application of Galerkin spectral method for tearing mode instability

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