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We present measurements of high power (25.7 kW), pulsed (800 ns), X-band (9.382GHz) microwave breakdown plasmas, including reflected power measurements, mixer reflected amplitude and phase measurements, optical emission spectroscopy (OES) measurements, and an analysis that estimates the average electron density and electron temperature. In addition, a six-region, 1-D model was used to determine plasma parameters and compare with the experimental results. The experimental results show that using a 43Hz repetition rate with an 800 ns pulse, fast (<300 ns) breakdown occurs in neon measured between 50 Torr and 250 Torr, producing plasma that lasts for over 7 µs. It also leads to large microwave reflections (70%) and an on-axis transmission attenuation of -15 dB. Moreover, a comparison between a 1-D model and mixer measurements shows that at 100 Torr, the neon plasma electron density peaked at 2x1012 cm-3, and the electron temperature peaked at 2.5 eV assuming a Maxwellian distribution. The addition of 2% Ar in Ne reduced the breakdown time and allowed OES measurements to determine the effective electron temperature. OES measurements of mixed (Ne/Ar: 98/2) argon line ratios (420.1 nm/419.8 nm) were used to determine the average effective electron temperature Te(eff)=1.2 eV, averaged over the entire 7ls plasma lifetime. They indicate that the electron energy distribution was not Maxwellian but, instead, tended towards a Druyvesteyn character. [ABSTRACT FROM AUTHOR]

The feasibility of using a photoionized, low-ionization potential organic seed gas to initiate a high pressure plasma discharge is examined and compared to radio frequency breakdown of high pressure argon alone. The seed gas, tetrakis(dimethylamino)ethylene, which has an ionization potential of 6.1 eV is ionized by an ultraviolet laser through 6.4 eV photon absorption, and forms a plasma column inside a vacuum chamber. The plasma absorbs additional power through inductive coupling of 13.56 MHz helical antenna radio frequency wave fields to the plasma through electron acceleration, ionization, and collisional damping. Laser initiation of 2-6 mTorr of the seed gas in 1-150 Torr of argon is accomplished and produces steady-state line-average plasma densities of n[sub e]≈4 × 10[sup 12] cm[sup -3] in a volume of 300 cm[sup 3]. The two-body recombination coefficient of the organic seed gas and its optimum partial pressure when mixed with argon are experimentally determined and analyzed. Particle loss and power requirements for maintaining the discharge are evaluated by examining ionization, diffusion, and recombination processes. [ABSTRACT FROM AUTHOR]

Presents a study on an experiment which produces a plasma sheet with a vacuum ultraviolet (VUV) laser in an organic gas using a cylindrical lens system for beam shaping. Experimental apparatus and diagnostics used; Presentation of a plasma diffusion/recombination model; Conclusions.

Presents information on a study which analyzed the production of tetrakis(dimethylamino)ethylene plasma by an ultraviolet laser beam. Illustration of the experimental arrangement; Photon absorption cross-section measurements; Electron-ion recombination coefficient measurement; Experimental setup for microwave reflection.