Processes in the cathode region of a low-pressure arc discharge

In this paper, we outline the physical aspects of the operation of an arc discharge in a low-pressure gas, when the particle path length is comparable to or greater than the dimensions of the discharge chamber. We analyze the processes occurring in the discharge gap after initiating plasma formation in the near-cathode region. We demonstrate a mechanism for a nonmonotonic dependence of the potential within the discharge volume. We note the determining role of oscillating electrons both during formation and during burning of a quasisteady-state arc discharge. Based on our proposed model, we calculate the formation time for a low-pressure discharge. We focus especially on description of the burning conditions for an arc with diffuse clamping of the current at a vaporizing cathode, which may be used in efficient sources of metal ions. We calculate the basic characteristics of such an arc, which are found to be in good agreement with experimental data.