Laser-Induced Discharge Propagation Velocity in Helium and Argon Gases

Abstract

IntroductionLaser propulsion 1) is one of the concepts of beamed energy propulsion that has a comparative advantage with respect to conventional chemical rocket systems. This includes high specific impulse and thrust, and low lift-off weight because of the capability of utilizing an off-board energy source. This concept has been demonstrated by the Lightcraft 2) : a laser-propelled launch vehicle. Impulse generation capabilities on the order of one-tenth Ns have also been demonstrated for an ablative-type of laser propulsion. 3) Other applications of laser-induced plasma discharge include, but are not limited to, laser-induced breakdown spectroscopic studies. [4][5][6] Laser-supported detonation (LSD) is known as overdriven detonation in which laser-induced discharge (LID) drives a shock wave. With a decrease in laser intensity S, regime transition occurs from LSD to laser-supported combustion (LSC) due to reduction in the laser-induced discharge propagation velocity u LID . At the laser intensity near this transition threshold, u LID approaches the Chapman-Jouguet (C-J) detonation velocity. The C-J detonation velocity, u C-J is as shown in Eq. (1).

Observation of Oblique Laser-Supported Detonation Wave Propagating in Atmospheric Air

“…With D ≥ 2.9 mm, the propagation velocity shows a unique tendency in terms of laser intensity, which is the same as earlier results. The beam diameter was measured more accurately than in previous studies conducted by the authors [21]. Also, the laser intensity is evaluated as the local laser intensity at the laser axis, with D = 1.2 mm.…”

“…Shimano et al reported gas-species effects on the propagation velocity with sufficiently large beam diameters. The velocities in argon, helium, and air have mutually differing tendencies in terms of laser intensity [21]. [7,10,[16][17][18][19].…”