Time of hot-spot formation in shock compression of microballoons in a condensed medium

摘要

The optical thermal radiation arising from the shock collapse of glass or polymer microballoons in a transparent condensed medium (water or polymerized epoxy resin) was detected. The temporal characteristics of the detected radiation in the pressure range 0.5-29 GPa at different viscosities of the material surrounding the pore were determined. The brightness temperature of hot spots was estimated to be 1600-3200 K at a pressure of 2-29 GPa. The length of the leading edge of the radiation pulse corresponding to the time of hot-spot formation increases from 2 center dot 10(-8) to 30 center dot 10(-8) s, depending on the shock-wave intensity and the viscosity of the material surrounding the pore. Analysis of the data shows that in the pressure range 5-29 GPa, hot-spot formation is dominated by the hydrodynamic mechanism of collapse and in the range 0.5-5 GPa, by the viscoplastic mechanism.