The Axial Expansion of a Field-Reversed Configuration Plasma as Induced by Neutral-Beam-Injected Fast Ions

Abstract

An axially expanding motion of a field-reversed configuration plasma can be observed numerically. This motion is induced by fast ions reciprocating between field-null x-points; the ions are injected obliquely from the axial end as neutral beam particles. A two-dimensional hybrid simulation is employed by assuming axisymmetry, where the beam ions are treated as particles and the plasma ions and electrons are treated as fluid. The diamagnetic beam current formed around the x-points and in the open-field region reduces the magnetic pressure, and then the plasma is found to expand axially.