Rotation during the Implosion of a Theta Pinch

Measurements of fields and pressure gradients during the collapse of a theta pinch allow determination of the ion azimuthal velocity from the radial component of Ohm's law. In hydrogen and nitrogen discharges Vθ was found to change sign across the current sheet. Ions rotated so as to carry an appreciable fraction of the current in the front of the sheet and moved so as to oppose current flow in the rear. The total angular momentum was approximately zero. These results agree well with the Düchs calculations of the influence of small transverse fields. Measurements of small transverse fields in the current sheet are presented.