Preheating effects in laser-driven shock waves

The radative preheating of the target in shock wave experiments is analysed by means of experiments and numerical simulation. Simulations have shown a small level of preheating in aluminium foils caused by the absorption of X-rays with energies close to the K-edge produced in the corona region. This preheating was checked experimentally with aluminium foils coated by gold and plastic to enhance and to reduce, respectively, the X-ray generated in the corona. The preheating and shock temperatures were measured by using the colour temperature technique. The reflectivity of the rear side of the foil was also used to detect small variations of temperature. Both diagnostics, colour temperature and reflectivity, agree quite well with the preheating temperature obtained from simulations.