Experimental studies of an extrap Z-pinch

Experimental studies of the formation, equilibrium and stability of a linear Extrap Z-pinch are reported. The Z-pinch discharge is generated between electrodes along the Z-axis of a linear octupole field produced by currents in four Z-directed rods. The combined discharge current and rod currents produce a magnetic field having a separatrix with four null X-points which define the corners of a square-shaped region where the high beta plasma discharge is contained. Bounding the pinch discharge with a separatrix produces equilibria which are stable against global kink modes for the 50- mu s duration of the discharge which corresponds to about 100 Alfven transit times. The equilibria, with line densities of about 3*1018 m-1, are consistent in magnitude and scaling with the Bennett relation.