A possible mechanism for interaction of a shock wave with a decaying laser plasma in air

TLDR: In this paper, the interaction between a laser plasma (generated by 20-ns 300-mJ pulses from a Q-switched ruby laser striking the tip of a metallic needle) and a 0.6-2.0-km/s planar or spherical shock wave (produced by electrical explosion of a 5 x 5-cm Al-coated dielectric film) is recorded on streak camera shadowgrams and analyzed.

Abstract: The strong absorption of a shock wave by a hot decaying laser or laser-induced carbon plasma (as observed by Barkhudarov et al., 1984, and Galkin et al., 1984) is investigated experimentally. The interaction between a laser plasma (generated by 20-ns 300-mJ pulses from a Q-switched ruby laser striking the tip of a metallic needle) and a 0.6-2.0-km/s planar or spherical shock wave (produced by electrical explosion of a 5 x 5-cm Al-coated dielectric film) is recorded on streak-camera shadowgrams and analyzed. It is found that the shock wavefront is accelerated and deformed by the lens action of the plasma and then relaxes in a time approximately equal to delta/C, where delta is the distance by which the shock wave leads the wavefront and C is the speed of sound behind the shock. The temperatures at the center of the plasma and at its edge when the primary shock wave separates from the hot plasma (2-3 microsec after the onset of breakdown) are estimated as 3400 and 1200 K, respectively. 6 references.