Hybrid Simulation of the Nonlinear Evolution of a Collisionless, Large Larmor RadiusZPinch

A two-dimensional, quasineutral hybrid code has been used to study the evolution of a Z pinch in which the ions are collisionless and have Larmor radii comparable to the pinch radius. The ions are treated as in a particle-in-cell model while the electrons are included through a simple fluid equation. $m=0$ instabilities are observed with the correct linear growth rates. These instabilities continue to grow exponentially, i.e., without saturation, until the plasma column is disrupted.