Compressibility effects on double tearing mode interlocking in differentially rotating plasmas

Abstract

Effects of compressibility on the double tearing modes (DTMs) in rotating plasmas are numerically investigated by using a compressible magnetohydrodynamics (MHD) model. It is found that due to the compressibility effects, the threshold of the interlocking magnetic island width in the slow and intermediate rotation regimes is larger than the counterpart in the incompressible plasmas. In the fast rotation regime, the compressible effect makes the DTM islands interlock more easily and faster. Moreover, in the very fast rotation regime, the plasma rotation can more effectively suppress the DTM islands. The scalings of the interlocking threshold in the different rotation regimes are obtained. Effects of plasma viscosity and beta on the DTM interlocking in the compressible plasmas are also discussed.