Summary of the First Workshop on Electrical Probes in Magnetized Plasmas

Abstract

The First Workshop on Electrical Probes in Magnetized Plasmas was held in Berlin, Germany, on June 13–15, 1994. Some highlights of the 17 talks are presented here. Although at the time probes were considered to be a reliable method to measure electron temperature, data was presented indicating very low values of the sheath power transmission factor, which can perhaps best be explained by systematic errors in the temperature measurement. A valuable framework for discussing the electron saturation current was provided by a model of current collection based on 100% recycling. Unfortunately, experimental results on the current ratio as a function of angle and the path of the return current were presented which could not be explained within the model. More successful was a model to explain the nonsaturation observed in the ion current as the result of growth of the Debye sheath. Two designs of ion sensitive probes were discussed, without coming to a full understanding of their operation. It was demonstrated that probes swept at very high frequencies can show new phenomena, whereas the averaging required for probes swept slower than the frequency of plasma fluctuations can distort the data.