Ultrafast time-resolved two-dimensional velocity mapping of the hot-dense plasmas generated by intense-laser pulses

Abstract

Experimental measurements of spatially resolved ultrafast dynamics of the critical surface in ultra-intense laser–solid interactions are essential for a proper understanding of the physical mechanism of the interaction. Resolving ultrafast motion at both the relevant length scales (micrometers) and timescales (femtoseconds) simultaneously has been a challenging task. Here, we demonstrate a novel technique for mapping the spatiotemporal dynamics of hot and solid dense plasma created by high contrast (picosecond contrast ∼10−9) femtosecond relativistic intensity laser pulses. This pump–probe Doppler spectrometry technique offers hundreds of femtosecond temporal resolution, together with a few micrometer spatial resolution across the transverse profile of the plasma. We present the evolution of the plasma surface critical for the probe pulse at the target front as well as the rear. Early time measurements (< 5 ps) using this technique provide very important information about shock wave generation and propagation and the state of the target rear.