RF Matchings Time Resolved Impedance, Power and Interferometer Measurements of Laser Initiated, RF Sustained Atmospheric Pressure Plasmas

Summary form only given. The feasibility of laser ionization and radio frequency sustainment of high-pressure seeded plasmas in argon has been demonstrated by our group in previous work. The tetrakis (dimethylamino) ethylene (TMAE) laser-initiated seed plasma recombination rates have also been characterized. Time resolved impedance and RF power measurements are performed on the plasma system in order to optimize and further characterize this laser-ionized and radio frequency sustained plasma. An atmospheric pressure range (40-760 torr), large volume (~2000 cc) air and air constituent (N₂ and O₂) plasma of high density (>10¹² cm^-3 ) is initiated by a 193 nm excimer UV laser and sustained by 13.56 MHz RF power through a helix coil antenna and matching system. The plasma loading impedance in the steady-state regime was characterized using high voltage probes and found to be of order 4.0 + j100.0 Omega, which varies dependent on the gas pressure and flow rate. The temporal variation of the plasma impedance and net coupled RF power are measured. Interferometer and spectroscopic analysis of plasma density, temperature, collision rate and recombination rates are discussed