Laser induced ramp compression of Zr on nano-second scales*

Quasi-isentropic ramp waves are advantageous in resolving wave structures due to phase-transitions and other dissipative phenomena. An open question is how this behavior changes with strain rate and kinetics of material transformation. To address this question, we study how phase transitions in Zr are affected when ramp waves are induced by short laser pulses extending over 1-10 ns time scales. Measurements are performed in thin 0.2 – 10 um Zr films using several different experimental platforms. Velocimetry data is collected using the line VISAR interferometry and analyzed using the Lagrangian and forward simulation methods. The results obtained are being compared to the corresponding Hugoniot and isentrope curves reported in the literature at longer time scales.