Chobei Yamabe

Parametric studies of uv preionization in TEA CO2 laser

The discharge characteristics of an electrical circuit for uv preionization in TEA CO2 laser are described. The suitable size of an electrode for uniform volumetric preionization of a laser gas is decided. The mechanisms of the ionization and the generated total initial electrons by uv photons are discussed. Moreover, both the effects of circuit parameters R, L on the intensity of uv radiation and the endurance test of the electrode for repeated discharges are also described.

Characteristics of a TEA CO2 laser preionized by ultraviolet light

The discharge characteristics of the main electrode both in low‐voltage and in high‐voltage regimes at 1 atm pressure are described. The number of initial electrons effective in the main gap discharge depend on the polarity of the main electrode. The photoemission of the electrons from the cathode situated near the uv source is very large and accounts for about 70 –80% of the total electrons. Also described is the influence of additive gas on both the electrical discharge and laser output power.

Interaction of TEA CO2 Laser Light with Laser Produced Plasma

The experimental results of the anomalous absorption due to the parametric instability of the laser produced plasma by focussing the double discharge type TEA CO2 laser light on the targets of carbon plate, polyethylene terephtalate film and polyethylene plate are described. The higher harmonics generation from the laser produced plasma is also observed.

Suppression of glow-to-arc transition in atmospheric pressure gas discharge of TEA CO2 laser by high frequency corona discharges

The transition from a glow discharge to an arc discharge at atmospheric pressure is suppressed, and homogeneous discharges are obtained, when the electrons produced by high-frequency corona discharge are scattered on the cathode surface continuously during the main discharge. This method is effective not only for mixed gases of CO2, N2 and He but also for mixed gases including oxygen.

Improved Performance of Discharge-Pumped XeCl Laser Using Ar/He Diluent

The performance of the discharge-pumped XeCl 308 nm excimer laser with automatic preionization has been improved through the use of an Ar/He mixture as the diluent gas. With Ar/He diluent, a higher laser peak power than that in Ar or He diluent and a longer lifetime than that in Ar diluent have been obtained below 2 atm, making it possible to fabricate a simpler laser tube.