Theory of probe for the plasma with negative ions

The potential distributions in the sheath and presheath regions of spherical and cylindrical probes are investigated as a function of the negative ion density ratio in both radial and orbital motion models. The presheath is given by a plasma solution with the quasineutrality. The potential in the sheath and the current-voltage characteristics are obtained by solving Poisson's equation with the initial value given by the plasma solution. The current-voltage characteristics of the ion saturation region are derived from the above solutions. The method for diagnostics by using the probe theory is suggested. (author)