Conditions for the formation and parameters of anodic plasma in a low-pressure arc discharge

The formation of plasma in the anodic region of a low-pressure arc discharge is analyzed and its parameters are determined based on experimental and numerical modeling. It is shown that at pressures of 0.01-0.1 Pa plasma electrons make the greatest contribution to the ionization process. These electrons are formed as a result of the relaxation of the flux of high-energy electrons accompanying the development of collective interaction processes in the region under study; this is the basic reason for the sharp growth in the electron density as the gas pressure increases and the previously not observed nonmonotonic nature of the pressure dependence of the plasma potential. Analogous dependences are also observed when the geometric dimensions of the electrode system are changed. The results of the calculation agree satisfactorily with experiment.