Atmospheric pressure microwave-powered microplasma source

Summary form only given. Portable low cost microplasma sources have various applications such as Bio-MEMs sterilization, chemical analysis systems and small scale materials processing. The application of microplasmas at atmospheric pressure is particularly attractive as it avoids the need for vacuum systems. Further, by using higher frequency energy (rf and microwave) to power the microplasma discharge, the erosion of electrodes can be reduced. In this investigation a microwave powered microplasma system based on a double-stripline structure is developed for the generation of atmospheric pressures plasmas with various feedgases and feedgas mixtures. The microplasma system is constructed with the top and bottom copper striplines separated by a dielectric material, either teflon or ceramic. The stripline structure powered at one end and the plasma formed at the other end where the two metal striplines are brought together to a gap distance that is varied from 50-400 microns. The feedgas is flowed through a channel in the dielectric such that it exits with the feedgas flowing between the gap created by the two striplines. The flow rate is varied from 0.3-3 slpm. The gas flow channel in the dielectric is 0.5 mm high by several millimeters wide. Argon and argon/oxygen microplasma discharges are formed in the gap between the two metal striplines. The microwave power used for the argon discharges varies from 2 to 60 Watts. The power density in the plasma discharge ranges from 500 to few 1000 W/cm . The plasma volume is obtained by photographic images of the discharge. The addition of oxygen to the argon feedgas increases the power density of the discharge. The gas temperature of the discharges is measured by adding a small amount of nitrogen gas to the feedgas and doing optical emission spectroscopy of the nitrogen rotational temperature. This paper will report on both experimental measurements, as well as initial simulation results of the microwave field behavior of the - ouble-stripline structure.