Toroidal effects on a helical pinch configuration with pitch reversal

Abstract

Toroidal effects on the outer magnetic surfaces of a configuration having a large toroidal plasma current that is stabilized by a pitch reversal produced by an external helical coil (OHTE) are investigated by both field-line tracing and an analytic expansion of the magnetic surfaces. Results of the two methods are compared. It is shown that both plasma position control and the helical coil winding law can be used to compensate undesired toroidal effects at both low and high beta.