Use of Electrostatic Probes in Plasma Physics

The principles of classical Langmuir probe theory are outlined to indicate the type of information theoretically obtainable by this technique. In the dense, hot plasmas and high magnetic fields encountered in modern plasma physics, difficulties arise both in instrumentation and in interpretation of the measurements. Because of these difficulties, perhaps the usefulness of probes lies primarily in the measurements of local fluctuating electric fields. The types of circuits required in probe work are described in general terms.