Control of streams generated by pulse-periodic laser breakdown in the intersected focused beams in high-pressure xenon

This paper reports the possibility of stabilizing and enhancing characteristics of pulse-periodic optical discharge (PPOD) in high-pressure xenon. The aim of this study was to explore the potential of using PPOD plasma as a high-brightness broadband UV radiation source for various applications. A new configuration to sustain PPOD was investigated, where two focused laser beams of a pulse-periodic fiber laser at a wavelength of 1.064 μm intersect at their focal waists. PPOD located in a single focused laser beam generally generates turbulent gas flow directed along the optical axis toward the laser beam that deteriorates the wavefront of the incident beam. PPOD sustained at the intersection of the two focused beams was shown to induce gas flow directed aside from the optical axes of the incident beams. This helps to increase the stability of the PPOD plasma from pulse to pulse. Data on the maximum spectral brightness of PPOD plasma radiation and stability have been obtained. Both estimates of the maximum electron concentration in the plasma from the measured maximum brightness and from the defocusing of laser radiation in the plasma give the value about Ne ≈ 2 × 1019 cm−3. It has been found that during PPOD with the repetition rate in the range fp = 20–21.3 kHz, resonant acoustic oscillations occur in the discharge volume, leading to a significant change in the pattern of gas streams around PPOD.