Spectroscopic analysis of ultra-clean, 20-fs, short pulse laser heated solid targets using time-resolved, copper K-shell emission

The Apollon short pulse laser facility has the capability of delivering multi-petawatt laser powers with an approximately 20 fs short pulse duration. An experimental campaign was recently conducted on the Apollon facility to investigate an electron fast ignition scheme. Among the suite of diagnostics was a toroidally bent Ge crystal spectrometer fielded in Johann geometry in conjunction with an ultra-fast streak camera. This allowed us to collect streaked emission spectra with ~xx picosecond temporal resolution. We will present the time-resolved spectroscopic data collected during this campaign along with preliminary analysis performed to extract electron temperature. As a byproduct to the spectroscopically inferred temperatures, the data demonstrate a surprising facility capability – generation of remarkably clean laser pulses with little to no prepulse. This capability enables the production of high-density plasmas from thin foil targets even without the use of tamper material which opens many experimental pathways including the potential for high quality opacity measurements among others.