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P: Plasmaphysik
P 12: Plasma Wall Interaction, Diagnostic and Low Temperature Discharges (Poster Session)
P 12.16: Poster
Friday, April 6, 2001, 12:30–15:00, AT2
Comparison of Different Beam Sources for the Helium Beam Diagnostics — •Harald Beyer1, Werner Bohmeyer2, Petra Kornejew2, Hans-Dieter Reiner2, and Gerd Fussmann2 — 1TFH Wildau, Institut für Plasma- und Lasertechnik, 15745 Wildau — 2MPI für Plasmaphysik, Bereich Plasmadiagnostik, 10117 Berlin, Euratom Association
In plasma physics, especially in fusion physics, the determination of electron density and temperature using a thermal He-beam is a well known diagnostics. For applying such a diagnostic a thermal He-beam is injected into the plasma and the electron density can be determined using the ratio of two singlet lines whereas the electron temperature is determined using a singlet and a triplet line. For reaching a high spatial resolution of these diagnostics a He-beam with a low divergence is desired. Such low-divergence beams can be generated using a nozzle-skimmer-arrangement but the technical effort is very high. Therefore, we studied the possibility to generate a low divergence He-beam using small orifice nozzles. For an evaluation the spatial profile of the light emission was measured. Some Laval-nozzles were included in the comparison. Furthermore, the beam profiles of all nozzles were systematically compared using a moveable sniffer probe. Summarising the results it has been shown that it is possible to realise small divergence beam sources but the manufacturing process and the smoothness of the inner surfaces of the holes have great influence on the beam quality. But nevertheless, the very low divergence of a nozzle-skimmer-arrangement can not be reached.