ID#: 171
Abstract Title: Visualization of Shock Waves at Early Stage of Milligram Charge Explosion
Session Title: Shock Interactions
Session Date: 7/31/01
Session Start Time: 3:40 PM
Contributing Author: Mizukaki, T.
Organization: Tohoku University
Country: Japan
Authors: Toshiharu Mizukaki, Harald Kleine, Masahide Katayama, Kazuyoshi Takayama
Short Abstract: In this paper, early stages of silver-azide pellet ignition by the irradiation of pulsed ND:YAG laser was quantitatively investigated. As in particular the shape of shock waves at very early stages was strongly affected by the orientation of cylindrical pellets and also the point on which the laser beam irradiated. In order to identify the early shock shapes, direction indicating color schlieren method was applied, in which the delicate variation of hue corresponds to the direction of density gradient in the test field. Cylindrical pellets were ignited either by direct irradiation of laser beam in air or by attachment on an optical fiber through which pulse laser beam was irradiated. The optimized orientation of the beam irradiation and also the direction of observations were very precisely determined. The effect of the pellet shape on shock wave formation was investigated numerically. In the series of experiments, 0.5 mg silver-azide pellets having slightly irregular shape were ignited again by the laser beam irradiation through the optical fiber and the motion of shock waves were visualize by schlieren method with IMACON468 high-speed camera. Numerical comparison was carried out using AUTODYN-2D and the result agreed reasonably well with the result of visualizations. Very minute structures of jet formation from micro-explosives and induced shock wave were resolved.