Transport, stability and relaxation of a spheromak

We consider a zero-β spheromak contained in a rectangular region having perfectly conducting boundaries in its minimum energy state, and we calculate its evolution. Our results may be summarized as follows. Since this state is a stable equilibrium, the initial evolution of the plasma is caused by diffusion. We simulate this using a transport code. We find that q at the magnetic axis drops and q(r) becomes flat. When q on axis drops below 0.5, the spheromak becomes unstable to an n = 2 kink. The plasma is then modeled dynamically; the kink displacement saturates and eventually reverses when a reconnection occurs. A new magnetic axis begins to form as the plasma relaxes toward a minimum energy state