A new method for shockless compression and acceleration of solid materials is presented. A plasma reservoir pressurized by a laser-driven shock unloads across a vacuum gap and piles up against an Al sample thus providing the drive. The rear surface velocity of the Al was measured with a line VISAR, and used to infer load histories. These peaked between $\sim 0.14$ and 0.5 Mbar with strain rates $\sim {10}^6–{10}^8{\mathrm{s}}^{-1}$. Detailed simulations suggest that apart from surface layers the samples can remain close to the room temperature isentrope. The experiments, analysis, and future prospects are discussed.

• Received 11 April 2003

DOI:https://doi.org/10.1103/PhysRevLett.92.075002