On the ignition voltage behavior of microwave microplasmas

Small-sized plasmas excited at microwave frequencies offer interesting applications from industrial processing to medicine. This paper presents first data on the ignition voltages of such microwave microplasmas. Using a quarter-wavelength resonant structure, an automated test system was set up, which allows to perform multiple ignition tests for each parameter constellation. Ignition voltage statistics are reported as well as the dependence on gas pressure for Ar, He and air in the range from 0.6 mbar to atmospheric pressure.