Synergistic effect of electron cyclotron current drive and poloidal shear flow on the tearing mode

Abstract

The separate and synergistic effects of both the electron cyclotron current drive (ECCD) and poloidal shear flow on the tearing mode are investigated numerically by using two-dimensional compressible magnetohydrodynamics equations in slab geometry. For the misaligned ECCD, effects of radial and poloidal misalignments have been compared emphatically. It is found that the suppression effect of ECCD is weakened with the increase of malposed ratio and it is more sensitive to the radial misalignment. The stability effect of shear flow is not positively related to the flow shear; the effects of starting moment of ECCD and shear flow are similar but not identical. The synergistic stability effect of ECCD and shear flow is more effective than ECCD or shear flow acts alone on the tearing mode without considering the “flip” instability. Furthermore, the combinatorial stability effect is more obvious when ECCD has a radial misalignment as a result of the continuous poloidal shift of magnetic island.