Characterization of a Compact, Low Cost, Atmospheric Pressure Plasma Jet Driven by a Piezoelectric Transformer

To fully realize the potential of non-thermal atmospheric pressure plasma technology, there is a need to develop inexpensive, compact devices that can be used for portable applications. One of the greatest challenges in generating a non-thermal plasma is producing an electric field sufficiently large to generate breakdown in atmospheric air. Piezoelectric transformers are solid state transformers that can produce large gains in voltage which has made them attractive candidates for plasma production. In this work, the electrical and optical characteristics of an atmospheric pressure plasma jet (APPJ) generated from a piezoelectric transformer were measured. With the piezoelectric transformer, plasma jets were produced with input voltages as low as 10 V and applied powers of less than 0.5 W. The piezoelectric driven jet was compared to an APPJ produced with a high voltage sinewave of comparable frequency to piezoelectric transformers optimal operating frequency. Both APPJs were examined in helium and argon for a variety of different flow rates and operating voltages. The length of the jets were nearly identical for all operating parameters with argon feed-gas but differed when helium used. In addition, measured current waveforms using the different approaches varied and optical emission spectroscopy showed a greater relative number of molecular nitrogen lines but lower relative emission of atomic oxygen lines for the piezoelectric transformer produced jet compared to the high voltage sinewave produced jet. Together, the results suggest the piezoelectric material has an influence beyond simple voltage amplification.