Influences of shock waves on high-pressure, pulsed glow discharge for excimer laser excitation

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.