The floating potential of spherical probes and dust grains. Part 1. Radial motion theory

A theoretical analysis of spherical probes in plasmas is presented. It is assumed that the probe is at floating potential, that ion motion with respect to the probe is radial and that the electrons are Maxwellian. The analysis shows that as probe radius divided by Debye length tends to zero, the ratio of floating potential to electron temperature also goes to zero.