Inflection-point method of interpreting emissive probe characteristics.

The use of emissive Langmuir probes in unmagnetized and weakly magnetized multidipole plasmas is investigated. It is shown that plasma potential, plasma electron temperature, and probe temperature can be determined from one probe characteristic curve. Data indicate that the inflection point of the current-voltage curve gives the plasma potential to an accuracy the order of the probe temperature Tw/e for weak probe emission. Effects of space-charge limiting and contamination of the probe are presented.