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P: Plasmaphysik

P 1: Plasma Wall Interaction

P 1.5: Talk

Monday, March 17, 2003, 17:05–17:25, FO1

Flow Velocity Measurements in a Magnetic Nozzle in PSI-2 and the Bohm Criterion — •T. Lunt¹, N. Ezumi², B. Koch¹, and G. Fussmann¹ — ¹Max-Planck-Institut für Plasmaphysik, Euratom Ass., Bereich Plasmadiagnostik, Mohrenstr. 41, D-10117 Berlin — ²Nagano National College of Technology, Nagano 381-8550, Japan

The magnetic field configuration in the plasma generator PSI-2 can be chosen in a way that the situation for the plasma is similar to that for a gas streaming through a Laval Nozzle. Taking the Bohm Criterion as a boundary condition, supersonic ion flow velocity would be expected within the region between the highest B-field and the neutralizer plate.

By means of Laser Induced Flourescence (LIF) the ion flow velocity and temperature has been measured in this region. It was found to be subsonic (M ≤ 0.3 ) in contrast to theory. The experimental results, the basic theory and possible reasons for the contradiction will be discussed.