New advanced operational regime on the W7-AS stellarator

• Published in: Physical review letters Vol. 89; no. 1; p. 015001
• Main Authors: McCormick, K, Grigull, P, Burhenn, R, Brakel, R, Ehmler, H, Feng, Y, Gadelmeier, F, Giannone, L, Hildebrandt, D, Hirsch, M, Jaenicke, R, Kisslinger, J, Klinger, T, Klose, S, Knauer, J P, König, R, Kühner, G, Laqua, H P, Naujoks, D, Niedermeyer, H, Pasch, E, Ramasubramanian, N, Rust, N, Sardei, F, Wagner, F, Weller, A, Wenzel, U, Werner, A
• Format: Journal Article
• Language: English
• Published: United States 01.07.2002
• ISSN: 0031-9007
• DOI: 10.1103/physrevlett.89.015001

A promising new plasma operational regime on the Wendelstein stellarator W7-AS has been discovered. It is extant above a threshold density and characterized by flat density profiles, high energy and low impurity confinement times, and edge-localized radiation. Impurity accumulation is avoided. Quasistationary discharges with line-averaged densities n(e) to 4 x 10(20) m(-3), radiation levels to 90%, and partial plasma detachment at the divertor target plates can be simultaneously realized. Energy confinement is up to twice that of a standard scaling. At B(t) = 0.9 T, an average beta value of 3.1% is achieved. The high n(e) values allow demonstration of electron Bernstein wave heating using linear mode conversion.