K-Shell and L-Shell Emission Spectra from Hot, Dense 130 fs Laser-Produced Plasmas

Summary form only given. Recent K-shell and L-shell X-ray spectroscopy measurements from mid-Z plasmas heated by a 130 fs, 400 nm laser beam focused at an irradiance of 10¹⁵-2times10¹⁷ W cm^-2 are reported. The main objective is to generate and study hot, T_e~300 eV, dense, n_e~10 cm^-3 , thermal plasmas in slab or thin buried layer targets under well-characterized conditions. The use of thin layer targets buried under carbon overcoats allows the study of tamped optically thin plasmas heated primarily by thermal electron conduction. Density and temperature gradients inside the layer are also minimized. Line emission diagnostics are studied that potentially can be extrapolated to higher energy plasmas. Our initial experiments have shown that an unexpectedly strong Cu K-alpha fluorescence signal indicates that significant laser energy is coupled into hot electrons at progressively higher laser irradiance corresponding to an Ilambda² above ~4times10¹⁵ W mum² cm^-2. A simultaneous measurement of T_Hot is required to determine the absorption mechanism as well as the plasma conditions. The laser plasma X-ray emission is studied with a suite of X-ray diagnostics: a time-integrated flat crystal, RbAP (001) spectrometer, and a RbAP (001) von Hamos curved crystal spectrometer with an 500 fs X-ray streak camera are used to study X-ray line emission in the 5-10 Aring wavelength range. A hard X-ray detector using multiple Ross filter pairs is used to determine the hard X-ray continuum emission and K-alpha X-ray emission for 5-100 keV