Studies On Shock Mechanisms Of Propagation And Attenuation In Laser Propulsion

The shock propagation and attenuation in solid in the process of laser propulsionand the impulse coupling process of Laser-Supported Detonation Wave with differentambient pressure are studied in this paper by analyzing the data simulation andtheoretical result.In the study of the shock propagation and attenuation in solid, according toconstraint conditions of the point-explosion spherical shock transmission, by adoptingthe polar coordinate for describing the isentropic mass and momentum conservationequation of spherical wave, the pressure on the solid target applied by theLaser-Supported Detonation Wave is determined. Based on the theoretical model ofrarefaction wave overtaking shock, the equicrural trapezoidal pressure profile isdeduced for the relation between shock pressure and time interval. The relationbetween shock pressure and propagation distance can be determined and iscorrespondence with the data simulation and experimental result.By the self-developed test system of laser impulse coupling to target based on thependulous method and the light electric tachometry, the experimental result is scaled.The pendulous equation of resistance model of low Reynolds number is founded andadopted for the initial impulse of laser coupling to target and examined by theexperimental method. Considering the experimental and hydrodynamic resultsgenerally, the components in the laser absorption zone can be determined byanalyzing the mechanical effect of Laser Supported Detonation Wave of interactionbetween laser and ambient gas or evaporation applied to the target. The ignitionthreshold of Laser Supported Detonation Wave can be determined by analyzing theplasma component in laser absorption zone under the standard atmosphere. Using thevacuum chamber for simulating the vacuum environment based on upward theoreticalprinciple, the relation between impulse coupling coefficient and ambient pressure. Byanalyzing the relation between experiment and numerical simulation, with theincrement of ambient pressure, the components in the laser absorption zone are fromplasma and target evaporation to plasma and ambient air. The phenomenon indicatesthe ignition mechanical transition of Laser Supported Detonation Wave, that is, LaserSupported Detonation Wave is ignited from target evaporation to ambient air. The experimental results can be divided into three stages based on components in the laserabsorption zone and the interaction between Laser Supported Detonation Wave andthe rarefaction wave, and the virial coefficient which indicates the micro phenomenonof plasma can be determined.These research results will provide the theoretical, numerical simulationreferences for laser processing technology, such as laser propulsion and heat treatmentof metal surface.