Flux core spheromak sustainment by electrostatic helicity injection is studied in resistive MHD. The geometry has magnetized electrodes at the ends held at a potential difference $V$. For $V>\mathrm{}{V}_c$ the central current column is kink unstable. The nonlinear state with $V$ just above $V_c$ has a large volume of flux surfaces, with rotational transform provided by the helical kinking of the column. As $V$ increases the kink becomes stronger, the tori are destroyed, and the field lines exhibit chaotic scattering. The distribution of field line lengths $L$, related to confinement and parallel current density, is studied. At larger $V$ or larger Lundquist number $S$, a limit cycle appears.

• Received 7 June 2000

DOI:https://doi.org/10.1103/PhysRevLett.85.4538