Effect of toroidal plasma rotation on double tearing modes in cylindrical geometry

Abstract

The effect of toroidal plasma rotation on q = 3 double tearing modes (DTMs) was studied numerically in cylindrical geometry using the method of reduced magnetohydrodynamic simulation. The results indicate that toroidal plasma rotation can reduce the growth rate of DTMs, but the magnitude of toroidal velocity has weak effect, especially without shear. When the shear of toroidal velocity exists, the suppression effect becomes better. Whether the velocity flow has shear or not, the growth rate of DTMs decreases as the magnitude of toroidal velocity increases. With the increase of velocity shear, the DTMs grow slowly. And the suppression effect of toroidal plasma rotation in early growth and transition stage is better, which means that the toroidal plasma rotation can suppress the linear growth of islands. Furthermore, the toroidal plasma rotation can suppress the evolution of poloidal stream. And the toroidal velocity shear on the q = 3 rational surface is more dominant than the magnitude of toroidal velocity in determining the DTM characteristics.