Influence of toroidal rotation on resistive tearing modes in tokamaks

Abstract

Influence of toroidal equilibrium plasma rotation on m/n=2/1 resistive tearing modes is studied numerically using a 3D toroidal MHD code (CLT). It is found that the toroidal rotation with or without shear can suppress the tearing instability and the Coriolis effect in the toroidal geometry plays a dominant role on the rotation induced stabilization. For a high viscosity plasma (τ R /τ V >>1, where τ R and τ V represent resistive and viscous diffusion time, respectively.), the effect of the rotation shear combined with the viscosity appears to be stabilizing. For a low viscosity plasmas (τ R /τ V <<1), the rotation shear shows a destabilizing effect when the rotation is large.

Solving the Grad–Shafranov equation using spectral elements for tokamak equilibrium with toroidal rotation

“…Meanwhile, plasma flow and flow shear can also directly affect plasma stability and transport [8,9,10,11,12,13]. In particular, flow shear may have stabilizing effects on neoclassical tearing modes(NTMs) [14,15], tearing modes (TMs) [16,17,18,19] and edge localized modes(ELMs) [20,12,21,22].…”

“…In particular, flow shear may have stabilizing effects on neoclassical tearing modes(NTMs) [14,15], tearing modes (TMs) [16,17,18,19] and edge localized modes(ELMs) [20,12,21,22]. It is found that sufficient toroidal flow opens up a stability window for resistive wall mode (RWM) [23,24,25,26,11]. On the other hand, plasma flow and shear can also directly modify plasma equilibrium due to the centrifugal effect.…”

Effect of local toroidal flow on double‐tearing modes in cylindrical geometry

“…[17] On the other hand, the toroidal plasma flow can delay the evolution of DTMs, [28] and the suppression effect depends on the magnitude of flow velocity and its shear rate on the rational surfaces. [29][30][31][32] The toroidal flows can affect the dynamics of magnetic islands through the coupling of magnetic curvature with pressure and density. [33] In order to investigate the influence of local toroidal flow (LTF) on DTMs, the reduced MHD (RMHD) simulation method is used to study the evolution of DTMs in various LTF cases in this work.…”

Effective Resistivity in Collisionless Magnetic Reconnection

“…Magnetic reconnection (MR) often occurs in plasmas containing sheared magnetic fields and can efficiently convert magnetic energy into the kinetic and thermal energies of the charged particles 1 – 3 . The process plays important roles in the evolution of the solar corona 4 , 5 , the geomagnetic tail 6 , 7 , the magnetosphere 8 , 9 , the intergalactic and interstellar, as well as laboratory plasmas 10 , 11 . In particular, collisionless or fast MR (FMR) on time scales much less than the inter-particle collision time can occur.…”