Temperature determination using Kα spectra from M-shell Ti ions -: art. no. 036408

The compact multipulse terawatt (COMET) laser facility at LLNL was used to irradiate Al-coated 2-50 mu m Ti foils with approximate to 10(19) W cm(-2), 500 fs, 3-6 J laser pulses. Laser-plasma interactions on the front side of the target generate hot electrons with sufficient energy to excite inner-shell electrons in Ti, creating K alpha emission which has been measured using a focusing spectrometer with spatial resolution aimed at the back surface of the targets. The spatial extent of the emission varies with target thickness. The high spectral resolution (lambda/Delta lambda approximate to 3800) is sufficient to measure broadening of the K alpha emission feature due to the emergence of blueshifted satellites from ionized Ti in a heated region of the target. A self-consistent-field model is used to spectroscopically diagnose thermal electron temperatures up to 40 eV in the strongly coupled Ti plasmas.