Overview on materials and technological developments for the LMJ cryogenic target assembly

The cryogenic target assemblies (CTAs) designed for Laser Megajoule (LMJ) experiments have many functions and have to meet severe specifications imposed by implosion physics, the CTA thermal environment, and the CTA interfaces with the Megajoule laser cryogenic target positioner. Therefore, CTA fabrication uses many challenging materials and requires several technological studies. During the last 2 years, many developments have enabled better collection of comprehensive data on target constitutive materials and improvements in the fabrication of the CTA base, hohlraum, and aluminum turret. Studies have been carried out (a) to better characterize thermal properties of materials allowing optimization of the thermal simulation of the hohlraum, (b) to improve the CTA base fabrication process in order optimize thermal studies of the LMJ experimental filling station (EFS), and (c) to determine coatings on the polyimide membrane that may limit the 300 K thermal effect on the micro-shell and increase the deuterium-tritium fuel lifetime. CTAs have been produced to evaluate fabrication knowledge, to characterize CTAs, to study air tightness, and to study filling and D2 ice layering on the EFS. An overview of the results that have been obtained during the past 2 years is presented in this paper. (authors)