Study of softhyphen;xhyphen;ray generation by laserhyphen;heating solid and gaseous tantalum plasmas with subpicosecond pulses

摘要

The efficiency of xhyphen;ray emission in the 17ndash;35 nm region from laserhyphen;heated solid and gaseous density Ta plasmas has been compared. An xhyphen;ray conversion efficiency of 0.4percnt; from a solid density Ta plasma requires a laser fluence of 200 J/cm2whereas the same efficiency in a gaseous Ta plasma with optimal density profile requires only 3 J/cm2. This is due to ultrarapid thermal diffusion in the solid and to the shorter attenuation length and duration of x rays emitted from the heated solid density plasma.