<title>Laser-produced plasma in high-speed flows</title>

Abstract

For the purpose of constructing the design rules of air-breathing laser launcher, the expansion of plasma, which was produced from air by focusing pulse laser, was investigated. A 1O-J-pulse TEA CO2 laser was used for these experiments. First, plasma was formed in a quiescent atmospheric air. Photographs and shadowgraphs were taken using an ICCD camera with high-speed gating. From the photographs, the propagation velocity along the laser axis was measured. The velocity was found around iO mIs much higher than that of a detonation wave calculated using LSD model. Since laser intensity at the plasma front was below the threshold for LSD regime, absorptionlexpansion mechanism other than LSD might predominate under the experimental condition. Shadowgraphs were taken to measure the expansion velocity of plasma and that of shock wave around plasma. The flow facility, in which plasma is formed in Mach 2 stream, was presented.

Numerical simulation of the expansion velocity of laser-induced plasma generated in transparent materials

“…This kind of laser support wave shields the laser energy, reduces the efficiency of laser processing, and changes the morphology of the damage target. Laser absorbing wave also has many applications in propulsion technology, the most typical is the bareboat technology developed by the US military in the last century, which has many advantages over the traditional propulsion technology, such as high specific impulse, low propulsion cost and so on [1][2][3][4][5] . For example, in 2017, Alberti [6] constructed a physical model related to the phenomenon of laser-induced breakdown (LIB) in non-equilibrium plasma, simulated the evolution of laser-induced air plasma and the process after breakdown, and compared the experiments to verify the accuracy of theoretical prediction.…”