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Summary form only given. Plasma generation in an organic molecular gas through a one-photon ionization process is studied. A 1-D model is derived to describe the photon flux flow and electron density evolution. Plasmas are generated in a low-ionization potential gas, tetrakis (dimethylamino) ethylene (TMAE) vapor, through a one-photon ionization process by an ultraviolet laser beam (E - 10 mJ, /spl tau/ - 17 ns) at 193 nm. A new method is used to measure the 193-nm ultraviolet (UV) photon absorption cross-section in TMAE. It is determined to be 1.1 /spl plusmn/ 0.3 /spl times/ 10/sup -7/ cm/sup 2/ from the axial profile of electron density. A high-density sharp boundary plasma sheet produced by a UV sheet beam obtained from the laser output through an optical system is examined. The microwave reflection from the plasma sheet is examined, and the potential application of a TMAE plasma as a mirror for microwave reflections is discussed. When TMAE is ionized in a higher-pressure background gas (argon/helium), a highly collisional, diffuse-boundary plasma can be produced.

Summary form only given. Measurements and analysis of the absorption, reflection, and scattering of electromagnetic waves due to electron cyclotron absorption zones and the presence of modulated scatterers in a plasma are presented. Measurements using a modulated homodyne detection system have been made that are sensitive to the backscatter from a movable probe in the plasma. The phase sensitive system is used to measure the local k-spectrum in the inhomogeneous plasma and is compared with WKB (Wentzel-Kramers-Brillouin) theory. A 12-cm-diameter by 2-m laboratory plasma is produced by a 2.45-GHz microwave source. Wideband wave absorption of 30-50 dB due to the electron cyclotron resonance zone in the 1.5-3.0 GHz range is measured. Experiments examining the microwave scattering frequency sensitivity of modulation-launched magnetoacoustic modes from a ceramic encapsulated PIN diode and from a disc Langmuir probe scatterer have also been performed.