Impurity redeposition in the SOL of TEXTOR after boronization
The material redeposited on the collector probe in the SOL of TEXTOR after boronisation was identified as a-C/B:D, i.e. as almost identical with the virgin coating. A conversion factor of 6.3 x 1.0 E17 C/cm2 for 100 nm thickness was found which corresponds to a density rho=1.26 g/cm2. Erosion of C and B from the coated graphite limiters caused stationary deposition during the discharge and distributions within the SOL. After 200 discharges the ratio B/C = 0.23 was lower than the original (B/C approximately 0.5-1). Observations made with the collector probe confirmed the reduced C and O contamination of the plasma due to boronisation. Carbon rates were determined shotwise after an integrated exposure by AES-depth profiling of the stratified deposit. A deposition rate of 1 x 1.0 E16 C/cm2s typically was found at a+2 cm and n(e) = 2.8 x 1.0 E13/cm3. It increased at lower densities as did the other impurities.
Bibliographic Reference: Article: Journal of Nuclear Materials, Vol. 176 & 177 (1990) pp. 150-157
Record Number: 199110879 / Last updated on: 1994-12-02
Original language: en
Available languages: en