Acoustic resonances in a pressurized discharge volume with xenon and instabilities of periodic-pulse optical discharges

Abstract

One of the factors inducing instability from pulse to pulse of periodic-pulse optical discharge (POD) or continuous optical discharge with deep periodic-pulse pumping modulation, or combined POD (CPOD), is the excitation of resonant acoustic oscillations in a pressurized discharge volume. In this work authors studied the violation types of the regular pulsations of CPOD thermogravitational convection plume in a closed discharge volume with xenon at a pressure of 15-45 bar, arising at certain periodic-pulse modulation repetition rates in the range 1-50 kHz. It was found that simultaneously with the appearance of failures in the behaviour of the convective plume and plasma stability, which in some cases led to the extinction of the discharge, resonant acoustic oscillations were excited in the discharge volume. Schlieren patterns of the gas around the discharge and the frequency spectra of the excited acoustic vibrations were recorded. Several types of instabilities were found that correspond to different modes of resonant vibrations. It was also found that at certain acoustic oscillation frequencies the convection process was stabilized with the suppression of regular pulsations.