Effect of toroidal rotation on plasma response to resonant magnetic perturbations in HL-2A

Abstract

<sec>Resonant magnetic perturbation (RMP), generated by externally applied magnetic perturbation coils, is an important method of controlling plasma edge localized mode. Many experiments have shown that RMP can effectively mitigate/suppress edge localized mode, but its intrinsic physical mechanism is not completely clear. The response of plasma to RMP is the key to understanding the RMP physics. In the presence of RMP, the circumferential symmetry of the tokamak magnetic field will be broken, forming a new three-dimensional(3D) equilibrium, and this process is called the plasma response to RMP. Currently, the parameter range and control effect of RMPs to control edge localized mode on different devices are quite different, implying that the plasma response to RMPs has different response results in different parameter ranges on different devices. Therefore, it is necessary to study the RMP response characteristics of specific devices.</sec><sec>In this work, the effect of the plasma rotation frequency on the linear response process of plasma to the resonant magnetic perturbations is investigated in the framework of MARS-F in the HL-2A configuration, and the physical reasons are analyzed in detail. It is found that the shielding and amplification effects in plasma response do not change linearly with plasma rotation frequency, since the plasma resistivity plays an important role. The shielding effect for the magnetic perturbation on the rational surface is enhanced with the increase of the rotation frequency in the high rotation frequency range. However, this rule no longer holds true in the low rotation frequency range due to the deviation of the strongest shielding position from the rational surface caused by the plasma resistivity. As for the amplification effect, the resistivity weakens the amplification effect of plasma response due to the dissipation of induced current. The variation trend of the amplification effect with the rotation frequency and resistivity is consistent with that of the core-kink response, which indicates that the amplification effect of the magnetic perturbation is mainly caused by the core-kink response.</sec>