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(EXP4/27) Characteristic Behaviors of Divertor Scrape-off Plasma in the TPE-2M Reversed Field Pinch

K. Hayase¹⁾, Y. Sato¹⁾, S. Kiyama¹⁾, Y. Maejima¹⁾, H. Koguchi¹⁾, K. Sugisaki¹⁾, M. Watanabe²⁾, M. Maeyama^3)
 
1) Electotechnical Laboratory, Tsukuba, Ibaraki, Japan
²⁾ Iwate University, Morioka, Iwate, Japan
³⁾ Saitama University, Urawa, Saitama, Japan

Abstract.  The divertor discharge of reversed field pinch (RFP) has been studied in TPE-2M (R/r = 0.87m/0.27m). The characteristic behaviors of divertor plasma and its effects on the core plasma are investigated by visible spectroscopy and probe measurements. The observed ion density profile at the divertor plate surface is rather smoothed out to a single hump possibly due to the particle scattering by a large amplitude fluctuation (around 15 %) of magnetic field in the open shell (divertor) region. An anomalous particle loss through the X-point region is suggested. The discharge depends on the position of X-point; when it locates near the plasma surface, the plasma may be less stable and the discharge terminates earlier presumably because the shell proximity of the core plasma surface is deteriorated. In this case, a large-amplitude, sometimes burst-like, fluctuation, is seen. The edge behaviors of core plasma in the shell region are less sensitive to the divertor field.

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