Simulation of the production of atomic hydrogen in a low-pressure-arc-discharge-based source

A model is proposed to simulate the production of atomic hydrogen in a low- pressure arc discharge. As a first step of simulation, the electron and ion densities, the currents of ions and fast and plasma electrons, and the cur rents of thermionic emission and secondary electrons have been calculated a nd then. based on the criterion for self-sustaining of the discharge curren t, calculations of the current-voltage characteristics are in good agreemen t with those obtained experimentally. The second step of simulation involve d calculations of the atomic hydrogen production rates. The model takes int o account the following mechanisms for the generation and death of hydrogen atoms: impact dissociation of molecules by fast electrons. dissociation by plasma thermal electrons, dissociation at the surface of a self-heating ca thode, and recombination of atoms at cold walls of a discharge cell. A theo retical analysis has shown that the three channels for the generation of at omic hydrogen make comparable contributions to the average rate of generati on of atomic particles. Comparison of experimental and calculated dependenc es of the atomic hydrogen density on the discharge parameters shows that th e proposed model provides an adequate description of the process of product ion of atomic hydrogen. (C) 2001 American Vacuum Society.