Efficient Creation of Laser Initiated, RF Sustained Atmospheric Pressure Range Plasmas

Summary form only given. We examine 193 nm (6.4 eV) UV photon ionization of low ionization level (6.1 eV) seed (15 mtorr) gas to reduce the power levels for radio frequency (RF) sustainment of large volume (500-2500 cc), high density (10^12-13/cc), atmospheric pressure range (50-760 torr) plasmas. These plasmas have potential applications in the areas of biological decontamination, radar absorption, thin films and processing of industrial materials. We have demonstrated the use of UV seeded plasma as a load for efficient inductive coupling at lower RF powers in argon. The tetrakis (dimethylamino) ethylene (TMAE), laser-initiated seed plasma recombination rates and observation of substantial delay in addition to direct ionization processes have been characterized in air and other gases. Current research is focused on the temporal measurement and matching of the laser and RF plasma load to the inductive helical antenna to produce high density, large volume plasmas. Time resolved antenna impedance and RF power measurements are performed to improve matching and determine the characteristics of the laser-ionized and radio frequency sustained plasma. In addition, millimeter-wave interferometry and optical emission spectroscopy diagnostics are used to determine the spatial and temporal plasma constituents. The addition of small concentrations (~2%) of hydrogen and measurements of line broadening are used together with the other diagnostics to determine the spatial and temporal plasma temperature, density, and recombination rates immediately after the rapid shut off of RF power