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The double pulse discharge has been demonstrated in a gas flow with velocity of 200 m/s which is generated by Ludwieg tube. A gas mixture of helium and argon is used to simulate the excitation discharge of excimer lasers. The shock waves and the gas density perturbation between the two successive discharges have also been visualized by using the shadowgraph technique with the high-speed image-converter camera. The second discharge at an equivalent pulse repetition frequency (f ) of 10 kHz becomes an arc through the heated column which is generated by the first discharge. At f = 5 kHz, the glow discharge can be produced between the electrodes, however, an arc is also observed through the heated column which locates somewhat downstream of the electrodes. Only glow discharge is succeeded at f = 3 kHz. These results clearly demonstrate that the heated column has decisive effects on the stability of repetitive pulse discharge. [ABSTRACT FROM PUBLISHER]

The high-pressure, pulsed glow discharge has been studied for further understanding of the excitation discharge on excimer lasers. The influences of shock waves on the discharge have been investigated eliminating the other factors, which may affect the discharge instabilities, such as gas density depletion, discharge products, residual ions and electrode heating. A shock wave of 1.2 in Mach number is produced by utilizing a shock tube with gas mixture of helium and argon in order to simulate the ArF excimer laser. The schlieren photographs of shock wave and direct images of light emitted from the discharge are recorded simultaneously by a high-speed image-converter camera. It is found that, if the shock wave does not reach to but close to the middle of the discharge region, glow discharge occurs only in front of the shock wave. Even if the shock wave passes through the middle of the discharge region, the glow discharge occurs only in front of the shock wave. However, an arc-like filament through the shock front is also produced. If the shock wave passes through the discharge region, the glow discharge can be produced again, however, a surface discharge is also produced between the main electrode and the pre-ionization pin electrode. [ABSTRACT FROM PUBLISHER]

The floating particles produced by the high-pressure, pulsed glow discharge on KrF excimer laser excitation have been visualized by the pulsed-laser scatter method. The double-pulse discharge experiments have also been carried out to study the effects of the floating particles on the discharge instabilities. The particles with diameter of the order of 100 µm are observed in the discharge region just after the discharge. The number density of the particles increases to ∼ 3 particle/cm3 at 200 ms after the discharge, and then decreases to ∼ 1 particle/cm3 at 500 ms. In the double-pulse experiment, the probability of arc in the second discharge reduces from 300 ms after the first discharge. It has been clearly demonstrated that the floating particles of the order of 100µm hardly affect the discharge characteristics. [ABSTRACT FROM PUBLISHER]

High-pressure, pulsed glow discharge has been studied for the excitation discharge in TEA gas lasers. The influences of the gas density depletion on the high-pressure, pulsed glow discharge have been investigated eliminating the other instabilities, such as shock waves, residual ions, discharge products and electrode heating. The gas density depletion is produced by utilizing a subsonic gas flow between the curved electrodes. A gas mixture of helium and argon is used to simulate the excimer lasers. The comparison has been made on the single-pulse discharge occurred in the presence of the gas density depletion with the second discharge on the double-pulse experiments in a stable gas. We have found that the big gas density depletion tends to induce the arc without other instabilities. In a stable gas, on the other hand, the second discharge of the double-pulse experiments becomes the arc in much smaller gas density depletion. The arc in the highly repetitive operation might be driven by some factors other than the gas density depletion. [ABSTRACT FROM PUBLISHER]

Very tightly-focused ion beam was obtained by “Plasma Focus Diode” (PFD), yielding focusing diameter of ∼ 360 µm, and power density of ∼ 0.1 TW/cm2 at the beam energy of ∼ 1.5 MeV. Enhanced energy deposition was observed in the interaction with aluminium target with the enhancement ratio of ∼ 1.5. In comparison of the experimental data with 1-D hydrocode simulation, good agreement is obtained between them. [ABSTRACT FROM PUBLISHER]