Use of probes to measure ion flux in a weakly magnetized plasma

摘要

Experimental investigations undertaken to examine the constancy of plasma density along magnetic field lines in a toroidal multipole field led to the following conclusions: The I‐V curves of Langmuir probes differ in regions of strong and weak magnetic fields. In regions of weak magnetic field, a Langmuir probe must be thoroughly cleaned for ion current to saturate, and even the clean probe saturates poorly both theoretically and experimentally, thus introducing ambiguity into the determination of ion flux. A new type of probe was developed for the measurement of ion flux, which is simple to construct and to use. This probe appears to measure ion flux reliably and unambiguously, and confirmed the constancy of plasma density along field lines in a levitated toroidal multipole.