Fluxes of boron in the scrape-off plasma of TEXTOR following boronization
During the first three weeks following boronisation of TEXTOR in March 1988, collector probes were exposed to ohmic and RF heated discharges in a wide range of plasma densities. With a fresh boronisation layer on all surfaces, the dominating relation to main plasma parameters was an increase in boron flux with decreasing plasma density. This behaviour is the same as that observed earlier for metal impurities, and reflects the energy dependence of physical sputtering yield at the limiters. In January 1989 the boron flux in the scrape-off layer was reduced by two orders of magnitude compared to the situation immediately after boronisation. During a gradual change-over from deuterium to helium filling gas, there was a drop in boron flux with increasing helium content in the plasma, suggesting that when only traces of boron were left in the machine, the release was dominated by chemical erosion.
Bibliographic Reference: Article: Journal of Nuclear Materials, Vol. 176 & 177 (1990) pp. 363-369
Record Number: 199110642 / Last updated on: 1994-12-02
Original language: en
Available languages: en