Anomalous Heating of Target Rear Surface in Laser-Solid Interactions

Abstract

The interaction of a sub-picosecond laser pulse with a solid target has been studied experimentally using focused laser intensities up to 1018 W cm-2. The measurement of emission at visible wavelengths from the rear side of the target and of Ka X-ray emission from the inside of the target indicates that an anomalous heating process occurs on the rear surface. This heating is most likely induced by the presence of a return current and/or the confinement of fast electrons on the rear surface, which are caused by the electric field of the sheath layer and the self-induced magnetic field.