Discharges with Safety Factor,q, <1 in a Noncircular Tokamak

Abstract

Characteristics of plasmas in Tokapole II (a noncircular poloidal divertor tokamak) with directly measured $q$ as low as 0.4 are discussed. This is a $q$ regime bounded by well studied $q>\mathrm{}1\mathrm{}$ tokamaks and $q\approx 0.1$ reversed-field pinches. After $q$ drops below 1, soft-x-ray sawtooth oscillations begin. During the oscillations the central $q$ values remain stationary and below 1, while a small oscillation in the edge $q$ values near $q=1\mathrm{}$ is observed.