ORTHOGONAL STRAINS AND ONSET OF PLASTICITY IN SHOCKED LIF CRYSTALS

We report experimental determinations of the elastic component of the transverse strain during passage of a shockwave. A 1 ns laser pulse drove an 60 kbar shock into an aluminum coated, radiation hardened, pure LiF single crystal. By diffracting a 0.25 ns pulse of x rays from a nearby high brightness, time-synchronized laser plasma, we measured the simultaneous compression of the lattice both parallel and transverse to the shock propagation direction with subnanosecond resolution. Definite compression was recorded in the inertially confined transverse direction, indicating the onset of plastic lattice response. Peak strains were of comparable magnitude in the orthogonal directions, but were not equal. © 1995 The American Physical Society.