Article

Plasma Investigations
2002. V. 40. № 1. P. 1–8
Ulyanov K.N.
Nondiffusion Theory of Electric Probes
Annotation
A mathematical model is suggested for the calculation of ion current to probes of different configurations in a locally collisional nonisothermal plasma. Compared with the diffusion models, the suggested model includes additionally the ion inertia, the ionization friction, and the effect of directional velocity of ions on the frequency of their collisions with atoms. The procedure for solving this nonlinear boundary-value problem enables one to determine the value of ion current, the distribution of ion concentration and velocity in the plasma, and the size of the positive space-charge layer. The basic dimensionless parameters of the problem are revealed, and their effect on the pattern of solutions is studied. It is demonstrated that the use of diffusion approximation for the calculation of the values of ion concentration and velocity on the plasma boundary leads, as a rule, to an error in the order of magnitude of the quantities being determined. The error in determining the ion current within diffusion approximation is likewise considerable; therefore, the use of the nondiffusion model helps increase the accuracy of determining the plasma parameters.
Article reference:
Ulyanov K.N. Nondiffusion Theory of Electric Probes, High Temp., 2002. V. 40. № 1. P. 1