Magnetohydrodynamic Simulation of Kink Instability and Plasma Flow during Sustainment of a Coaxial Gun Spheromak

Abstract

Kink instability and the subsequent plasma flow during the sustainment of a coaxial gun spheromak are investigated by three-dimensional nonlinear magnetohydrodynamic simulations. Analysis of the parallel current density λ profile in the central open column revealed that the n = 1 mode structure plays an important role in the relaxation and current drive. The toroidal flow (v t ≈ 37 km/s) is driven by magnetic reconnection occurring as a result of the helical kink distortion of the central open column during repetitive plasmoid ejection and merging.

Physics of forced magnetic reconnection in coaxial helicity injection experiments in National Spherical Torus Experiment

“…This approach, known as driven CHI, is being currently investigated in small machines, 16,17 and also being studied through MHD simulations. 18 This paper is organized as follows. The computational model is described in Sec.…”