Spheromak Formation by Theta Pinch

Abstract

Production of a spheromak configuration is attempted by using a theta pinch combined with a z-discharge. A loop current which is formed by a z-discharge current flowing in the plasma and reversing on its surface generates a toroidal field in the spheromak. Mechanism of the current reversal is explained from toroidal flux conservation in the plasma during implosion phase of the theta pinch. It is found that the reverse ratio is controlled in actual experiments by an external inductance of the z-discharge circuit, a length and a compression ratio of the plasma. Experiments show that 70% reversal of the z-current is easily realized using a conventional theta pinch.