Plasma Reflectivity and Propagation Effects in a Femtosecond Laser Pulse

The development of table-top terawatt lasers, producing intensities of 1015−1018 W/cm2 in pulses of duration on the order of a picosecond or less, has opened up a whole new regime for plasma physics. The interactions occurring in a femtosecond-pulse laser-produced plasma differ in a number of important respects from the traditional mechanisms observed in, for example, an ICF plasma. Much of the interest in the field of femtosecond plasma physics centres on the production of ultrashort pulses of x-rays [1], and there has also been a considerable amount of work devoted to studies of energy absorption, in an attempt to characterise the hot, near-solid-density plasmas produced [2-4].