Electron sink to probes in moderate pressure plasmas and in plasmas in magnetic fields

The effect of the electron sink to probes in moderate pressure plasmas and in plasmas with a magnetic field is examined. It is shown that the formulas for the electron currents to spherical and cylindrical probes based on the theory of the sink effect are the same as those based on the kinetic theory in the diffusive regime. Similar agreement is obtained for a cylindrical probe oriented parallel to a magnetic field when the probe dimensions are large enough. It is shown that the formulas for the sink parameters obtained here are identical under certain conditions to those used in Bohm's theory for probe saturation currents.