Complete suppression of Pfirsch-Schluter current in a toroidal l=3 stellarator

Pfirsch-Schluter current (PSC) is an inherent property of a finite pressure toroidal plasma equilibrium in tokamaks and stellarators. However, it has been pointed out (V.D. Pustovitov, Nucl. Fusion 36 (1096) 583) that the PSC in a conventional stellarator could be suppressed completely by adjusting the external vertical magnetic field so that it satisfies the condition tha t the quantity characterizing the inhomogeneity of the magnetic field stren gth on a Aux surface is a flux function. In this article an example is pres ented of such an iota = 3 stellarator equilibrium. Complete suppression of PSC in a finite beta plasma is shown numerically by using the fixed boundar y version of the VMEC code. The calculated equilibrium is also analysed fro m the viewpoint of the Boozer magnetic spectrum. It is shown that a reducti on of the poloidal inhomogeneity of the magnetic field strength is essentia l for reducing the PSC.