Experimental observation of elevated heating in dynamically compressed CHfoam

We present an experimental result of significantly increased heating in a laser-driven blastwaveexperiment carried out at the OMEGA laser facility. Abnormally high temperatures wereobserved in warm dense CH compared to older experiments and theoretical predictions. Thehigher temperatures in compressed CH were linked to an improved smoothness of the laserintensity profile, which resulted in better efficiency of the drive and coupling of more energyinto the system compared to previous similar experiments. Fifteen beams with combinedintensity of∼7×1014W cm−2and a square intensity profile with 2 ns duration were used todrive a strong shock, which subsequently developed to a blastwave travelling through lowdensity CH foam creating warm dense matter. Multiple diagnostics were used to examine thethermodynamic conditions in the warm dense CH foam. Velocity interferometry (VISAR) andstreaked pyrometry (SOP) observed increased blastwave velocities, while x-ray Thomsonscattering (XRTS) measured elevated temperatures of 17.5−35 eV in compressed CH foam.The experimental results were compared to hydrodynamic simulations and a potentialcontribution from x-rays to the elevated temperatures in the dense material was considered.