Measurement and monte carlo computations of Hα profiles in front of a TEXTOR limiter

Abstract

In order to assess the existing data for hydrogen reflection and penetration into boundary plasmas, the spectral profile of H_α emitted in front of a TEXTOR limiter has been measured with a high resolution spectrometer and calculated with the EIRENE code. The emission has been investigated for standard recycling conditions of hydrogen, but also for the case that this recycling is superimposed by a strong puff of hydrogenic molecules injected through a hole at the limiter tip. This latter case was used to calibrate the molecular transport model. The H_α profiles during recycling have been observed and calculated for both a graphite and a stainless steel limiter. As expected, the number of reflected particles strongly increases in going from the C to the Fe limiter and seems to be slightly overestimated by present surface reflection databases.