A Simulation Study of Hall Effect on Double Tearing Modes

Abstract

A Hall magnetohydrodynamics (MHD) simulation is carried out to study the dynamic process of double tearing mode. The results indicated that the growth rates in the earlier nonlinear and transition phases agree with the previous results. With further development of reconnection, the current sheet thickness is much smaller than the ion inertia length, which leads to a strong influence of the Hall effects. As a result, the reconnection in the late nonlinear phase exhibits an explosive nature with a time scale nearly independent of resistivity. A localized and severely intensified current density is observed and the maximum kinetic energy is over one order of magnitude higher in Hall MHD than that in resistive MHD.

Nonlinear evolution of double tearing mode with guiding magnetic field

“…18 In the earlier studies, 15,16,[20][21][22] it is indicated that the dynamic evolution of the system contains: a linear phase, an early nonlinear phase, a transition phase, the explosive nonlinear phase, and a decay phase. With our initial perturbation, there is no linear phase.…”

“…The dynamic properties of the DTM for different magnetohydrodynamical (MHD) models have been widely studied under various conditions, such as external shear flow, [9][10][11] bootstrap current, 12 anomalous electron viscosity, 13 and collisionless effects. [14][15][16] Recently, it is suggested that the internal transport barrier may be related to the strong shear flows associated with the DTM. 17 In linear studies of the DTM, 18,19 a necessary condition is that the separation of the rational surfaces has to be sufficiently small.…”

Influence of shear flows on dynamic evolutions of double tearing modes

“…Moreover, the nonlinear evolution of DTMs could lead to a significant reduction of plasma pressure and the degradation of the energy confinement during tokamak discharge [7][8][9]. It is therefore necessary to understand the mechanism of DTMs, and to develop effective methods to suppress DTMs [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29].…”