Spectroscopic measurements of the ion temperature profilein front of a limiter in TEXTOR-94

Ion temperatures have been measured in front of a limiter inTEXTOR-94 under various plasma conditions by means of theDoppler broadening of the C5+ line (λ = 529 nm), which is excited by charge exchange processes withhydrogen (deuterium) atoms recycled at the limiter surface. Theion temperatures have been compared with electron temperaturesmeasured by atomic beam techniques. It has been found that theion temperatures are considerably larger than those of theelectrons. In the scrape-off layer (SOL) the ratio between the ionand electron temperatures (Ti/Te) can reachvalues of up to three at low plasma densities, but this ratiodecreases with increasing density. The SOL e-folding lengthof the ion temperature is much larger than that of the electrontemperature. The influence of the test limiter position rL on the ion temperature measurements has been investigatedbut found to be of no significant importance.