THEORY OF ELECTRON CURRENT TO A SPHERICAL PROBE AT INTERMEDIATE PRESSURES

The problem of the calculation of the electron current to a retarding spherical probe at intermediate gas pressures is discussed. The current to the probe is expressed in terms of the probability with which an electron, from the undisturbed plasma, will reach the probe surface. This probability is obtained using the Monte Carlo method. It is shown that the computer simulation has to be performed only for the laser few free paths of the electron near the probe surface. An integral equation for the electron energy distribution function in the undisturbed plasma is received from the expression for the electron current.