Spectroscopic Measurement of a Piezoelectric Transformer Driven Atmospheric Pressure Plasma

A piezoelectric transformer was used to stimulate a high pressure, room temperature helium plasma. The piezoelectric transformer was used to convert a low-amplitude input voltage into a high voltage by driving the transformer into electro-mechanical resonance. The plasma was formed of helium and nitrogen species in a quartz tube at a total pressure of 1.8 atm, and time-resolved methods demonstrated the plasma ignited and extinguished twice per resonance period. The average ion temperature was determined by collecting an optical emission spectrum from the plasma, and then using Specair to parametrically search for a best-fit to the data, where parameters impacting band-head of broadening of specific transitions were systematically adjusted. Using the fitting routine, we established the plasma temperature was between 28 and 32 meV.