PLASMA-SURFACE INTERACTIONS IN THE ALCATOR C-MOD TOKAMAK

摘要

Alcator C-Mod is a high-field tokamak with which experiments were initiated in April 1993. The divertor and the first-wall have plasma-facing surfaces of molybdenum. The divertor has a configuration which is closed in comparison to other, currently operating tokamaks, The combination of divertor geometry and high field (density) make Alcator C-Mod an ideal experiment to investigate dissipative (radiative/CX) divertor scenarios. Single-null divertor operation has become the standard mode of operation. Relatively clean plasmas (Z(eff)less than or equal to 1.3) are obtained with short periods of baking and electron cyclotron discharge cleaning only. Impurity source rates and screening have been investigated with an extensive set of wavelength-filtered diode arrays and spectrographs. Carbon and oxygen and molybdenum dominate the impurity levels. The molybdenum source from the divertor proper is negligible. [References: 10]