Discharge instabilities in high-pressure helium-fluorine laser gas mixtures

Discharge instabilities in F-2 based excimer gas lasers are investigated using a small-scale discharge system. After preionizing the gas volume, a fast rising voltage pulse initiates the discharge. The temporal development of the discharge is monitored via its fluorescence by an intensified CCD camera with a gating time of 10 ns. Homogeneous discharges are produced in gas mixtures of He/1 mbar F-2 and He/1 mbar F-2/30 mbar Xe at a total pressure of 2 bar for pump pulse durations up to 70 ns (FWHM). The addition of Xe to He/F-2, mixture does not lead to discharge instabilities while the introduction of more F-2 results in hotspot and filament formation.