Scaling laws for temperature and reflectivity of plasma generated by a short neodymium laser pulse

Plasma was generated by 35 ps 1.06 μm laser pulses, focused on to plane Perspex slabs in vacuum. Reflectivity and electron temperature were measured as functions of incident laser intensity between 2 x 1011 and 2 x 1014 W cm-2. The measured scaling laws were compared with a one-dimensional code. In this short pulse regime, the coronal electron temperature is determined by the balance between inverse bremsstrahlung plasma absorption and enthalpy flow. The electron temperature measured from x-ray emission is interpreted as that of the cooler overdense plasma. For the interpretation of experimental measurements, the importance of the ratio between density scale length and focal spot diameter is stressed. (author)