Elastic Explosions in Solids Caused by Radiation

If intense radiation (coherent light, secondary ionization, or sustained fission) is put into a solid in a time δ short compared with the elastic relaxation time, a resulting internal ``explosion'' may cause multiple fracturing and other damage. We postulate that at t=δ≃0, the radiation causes a uniform dilation within a cylindrical region of radius a. Solution of the relevant wave equation (continuity preserved at r=a) indicates that a rarefaction wave of increasing amplitude moves inward from a with velocity v during the time interval, 0