COMPUTER-CONTROLLED PROBE DIAGNOSTIC SYSTEM AND APPLICATIONS IN A MAGNETIZED LABORATORY PLASMA

A computer controlled acquisition and evaluation system for electrosta tic probes is presented. Fully automatic evaluation of the probe chara cteristics yields electron temperature, plasma potential, and density during the recording. Two-dimensional probe positioning is accomplishe d with stepping motors. The system is characterized by 12-bit probe cu rrent resolution and extremely wide probe voltage range (+/-130 V). It is tested in a collisionless argon magnetoplasma and compared to stan dard wave diagnostic techniques for magnetized plasmas, i.e., the reso nance cone technique. The influence of the probe radius on the electro n current in a magnetized plasma is studied experimentally. The two te chniques yield identical density and temperature values within 20% acc uracy and therefore show the reliable applicability of the automatic e valuation system.