Time resolved inner-shell spectroscopy of laser produced plasmas using a HOPG crystal in Von Hamos geometry*

Time resolved heat transport in warm dense matter, an essential component of the Fast Ignition concept, has been studied using inner-shell spectra from Ti and Al/Ti/Al foils. Thermal emission is generated by irradiation with either 527 nm and 1ns or 1053 nm and 5 ps pulses using the Vulcan laser at RAL. Fluorescence emission was recorded with a ZYA grade HOPG crystal used in mosaic focusing mode and Von Hamos geometry. The crystal was coupled with a Kentech Low Magnification Streak Camera, fitted with a fluffy CsI photocathode, providing a temporal resolution of about 50 ps. Although the small dynamic range of the streak camera restricts measurement of the full duration of He-alpha emission, our data indicates that the FWHM duration of the resonance line is approximately 1.5 ns when the Ti foil is irradiated with 1 ns pulses.