Plasmas sustained by repetitive nanosecond pulses: recombination mechanisms in Ar with trace amounts of H2O

A 0D kinetic model was developed to understand the electron-ion recombination in a plasma generated by high repetition frequency nanosecond pulses in argon with trace amounts (0.1% or less by volume) of water vapor at a total pressure of several Ton. The influence of trace amounts of water on the electron temperature and density decay was studied by solving electron energy and continuity equations. In pure argon, Ar+ ions dominate, the electron temperature is very slow to thermalize, and the recombination of electrons is also very slow. The presence of trace amounts of water impurity drastically reduces the electron thermalization time and increases the rate of recombination. The kinetic model provides a good fit to the previously acquired experimental data.