Influence of plasma density gradient on the tearing mode with the poloidal shear flow

Abstract

The influence of the plasma density gradient on the m/n = 2/1 and m/n = 4/1 (m is the poloidal mode number and n is the toroidal mode number) tearing mode instability with poloidal flow and flow shear is investigated. Using the analytical solution that we obtained in a previous work and mainly focused on the factors of plasma density and poloidal shear flow, we found that the plasma density has a stabilizing effect on the classical tearing mode, and the poloidal equilibrium flow can intensify this beneficial effect. The density gradient was detrimental to the stability of the tearing mode. The effects of both density and density gradient are slight, but the effect of poloidal flow on the plasma density is significant. Considering that the plasma density changes with the poloidal flow, the values of the tearing mode stability index ∆′ clearly change. Our investigation also found that compared with the negative flow shear, the positive flow shear is beneficial to the stability of the tearing mode, and a larger poloidal flow shear has a better stabilizing effect on the classical tearing mode.