You searched for: “electric probe
electric probe, electrostatic probe
A tool used to measure electron temperatures, electron and ion densities, space and wall potentials, and random electron currents in a plasma.

It consists substantially of one or two small collecting electrodes to which various potentials are applied, with the corresponding collection of currents being measured.

This entry is located in the following unit: electro-, electr-, electri- (page 12)