MHD Stability of a Plasma in a System of Coupled Axisymmetric Adiabatic Open-Ended Traps

Abstract

Conditions for convective plasma stability in a system of coupled axisymmetric open traps with sign-alternative curvature of magnetic field are analyzed both in the MHD model and the Kruskal–Obereman kinetic model. For a couple of nonparaxial simple mirror cell and a semicusp, the “radial’ interval where a hollow plasma can be stable is determined, as well as the range in which the ratio of the pressures in component cells should lie. Both external and internal plasma boundaries are stable in accordance with the average minB principle, provided that the pressure profiles in the cells are made consistent. The plasma compressibility plays an essential role. The stability of the cells against the global mode (as in the Ryutov–Stupakov trap) is sufficient but not necessary for stabilizing the chain. For the couple under consideration, the stability margin is not small.