Scaling studies of spheromak formation and equilibrium

Formation and equilibrium studies have been performed on the Swarthmore Spheromak Experiment (SSX). Spheromaks are formed with a magnetized coaxial plasma gun and equilibrium is established in both small ${\mathrm{(d}}_{\mathrm{small}}\text{=0.16}$ m) and large ${\mathrm{(d}}_{\mathrm{large}}{\text{=3d}}_{\mathrm{small}}\text{=0.50}$ m) copper flux conservers. Using magnetic probe arrays it has been verified that spheromak formation is governed solely by gun physics (in particular the ratio of gun current to flux, ${\mu }_0{I}_{\mathrm{gun}}{\mathrm{/\Phi }}_{\mathrm{gun}})$ and is independent of the flux conserver dimensions. It has also been verified that equilibrium is well described by the force free condition $\mathrm{\nabla \times }{B}\mathrm{=\lambda }{B}$ $\mathrm{(\lambda =}$ constant), particularly early in decay. Departures from the force-free state are due to current profile effects described by a quadratic function $\mathrm{\lambda =\lambda (\psi )}$ . Force-free SSX spheromaks will be merged to study magnetic reconnection in simple magnetofluid structures.