Strong shock wave generation by the interaction of a giant laser pulse with a solid target

The interaction of a focused giant laser pulse with a carbon target immersed in a gas is shown to be a source of a strong shock wave at appropriate gas pressures. High-speed image-converter photographs show the development of a complex luminous shock structure near the target surface as a function of time in the gases air, argon and helium, for pressures in the range 0·1-10·0 torr. Initial Mach numbers up to 200 have been recorded for the luminous front in argon. Initially a luminous region is created at the target surface. The displacement of the leading edge is proportional to the n th power of time with n similar 0·6 to 0·7 for the first 400 ns after initiation, and n =0·4 for a few hundred nanoseconds after this time, when the front attenuates. A second sharply defined luminous front, also with n =0·4, is then observed.