IMPROVED PLASMA PERFORMANCE IN TEXTOR WITH SILICON COATED SURFACES

Coating of the walls of TEXTOR with silicon has led to improved tokama k plasma performance. Very low concentrations of C, B, and O are measu red. Radiation from silicon is located at the plasma periphery at r/a greater-than-or-equal-to 0.75 and decreases with increasing plasma den sity. Density limits are enhanced by 30% as compared to boronized cond itions; large density gradients and low electron temperatures at the e dge (< 10 eV) are obtained. The improved confinement regimes observed earlier at low densities [tau(E) = 1.7 x ITER L 89-P (International Th ermonuclear Experimental Reactor)] were extended to significantly high er densities in spite of a high radiative power fraction.