Formation of dee-shaped plasmas with single-null poloidal divertor in Doublet III

Abstract

As a result of the vertical elongation of dee-shaped plasmas, natural single-null poloidal-divertor equilibria have been stably obtained in the upper half of the Doublet III vacuum chamber with a plasma current of 320 kA, a major radius of 140 cm, an average minor radius of ~45 cm, and a vertical elongation of 1.3–1.4 in the plasma cross-section. Without employing any particular divertor chamber, this simple divertor reduces the influx of metallic impurities to the main plasma and the re-cycling of charged particles in the periphery of the main plasma. The divertor reduces the radiation loss power and improves the energy confinement time.