PROPERTIES OF A VACUUM-ULTRAVIOLET LASER CREATED PLASMA SHEET FOR A MICROWAVE REFLECTOR

A 193 nm excimer laser and a custom fabricated cylindrical lens system is used to produce a plasma sheet of 8 cm X 30 cm X 0.4 cm in tetraki s(dimethylamino)ethylene (TMAE), a low ionization energy organic gas. Plasma density variation due to photon absorption is studied by scanni ng the filling pressure of TMAE between 12 and 150 mTorr. A high densi ty (n greater than or equal to 2.0 X 10(13) cm(-3)), low temperature ( T-e approximate to 0.8 eV) plasma sheet of 4 mm thickness is obtained with less than 50% spatial density variation over the 30 cm axial leng th. Charge recombination is found to be the dominant process for t les s than or equal to 1.2 mu s with the plasma diffusion playing a pertur bational role. A one-dimensional plasma model is utilized to model the experimental plasma data by treating the diffusion as a perturbation. This study shows that the recombination coefficient is 1.8 +/- 0.1 X 10(-7) cm(3) s(-1) and the diffusion coefficient is 2.8 +/- 0.4 X 10(4 ) cm(2) s(-1). The plasma sheet has attractive properties for a microw ave agile mirror. (C) 1995 American Institute of Physics.