[en] The High Power laser Energy Research facility (HiPER) is a European project dedicated to demonstrating the feasibility of producing energy by laser-driven inertial confinement fusion. A first design of the fast ignition cryogenic target has been established. It is composed of a thin-walled micro-shell with an inserted gold cone and filled with deuterium-tritium (DT) fuel by means of a capillary (conically guided capsule). After assembly, targets must be tight at cryogenic temperatures (16 to 19.6 K). In order to evaluate the manufacturing feasibility of a single-shot target prototype, a program has been adapted from the Laser Megajoule (LMJ) cryogenic target fabrication know-how. Target component study for HiPER concerns a hollow gold cone (25-deg half-angle and ∼25-μm thickness), a thin polymeric micro-shell (2-mm diameter and 3- to 10-μm thickness), and a silica capillary (30-μm outer diameter). First gas-tight targets at 77 K have been produced (helium gas leak rate similar to 1.4 * 10^-11 Pa.m³/s). Major efforts have been focused on thin-walled micro-shells, robust gold cone fabrication, and target assembly (minimizing of the glue quantity as well as helium gas leak tests) and will be discussed in this paper. (authors)

[en] The Megajoule Laser cryogenic system fills, transports and inserts on the Cryogenic Target Positioner (CTP) individual Cryogenic Target Assemblies (CTAs), which are manipulated at about 20K by several cryogenic grippers.This CTA has to meet severe specifications imposed by implosion physics, its own thermal environment, and to respect a lot of interfaces with the permeation cell of the filling station, the several cryogenic grippers, the Megajoule laser interaction chamber,... Therefore, the CTA definition is very complex, and induces a lot of challenging tasks for its fabrication. During the last year, many improvements have been achieved allowing the realization of the first CTA prototype at scale one

[en] Low density foams (in this work, foam density refers to apparent density) are materials of interest for fusion experiments. Low density poly(4-methyl-1-pentene)(commercial name TPX) foams have been produced for 30 years. TPX foams have been shown to have densities as low as 3 mg.cm^-3, which is very close to air density (1.2 mg.cm^-3). Around this density foams are very light and highly fragile. Their fabrication is thus a real technological challenge. However, shrinking always appears in ranges ranking from 25% to almost 200%. As a result, the apparent density of the final foam never matches the expected value given by the precursor solution concentration. Besides, even if the mold dimensions are precisely known, shrinkage is never linear, and foams have to be machined for precise density measurement. In our work we present a fabrication process for TPX foams and discuss machining and density measuring issues. Particularly, we have found that there are volume and weight limits for a determination of density within the range of 3% uncertainty. This raises the question whether density should rather be determined directly on millimeter-sized targets or should be performed on a bigger scale sample prepared from the same batch. (authors)

[en] To carry out laser plasma experiments on CEA laser facilities, a R and D program was set up and is still under way to deliver complex targets. For a decade, specific developments are also dedicated to 'Ligne d'Integration Laser' (LIL) in France and Omega facilities (USA). To prepare the targets intended for the first experiments on the Laser 'Megajoule' (LMJ) facility, new developments are required, such as cocktail hohlraum fabrication, gas barrier coating and foam shells developments. For fusion experiments on LMJ, an important program is also under way to elaborate the Cryogenic Target Assembly (CTA), to fill and transport the CTA and to study the conformation process of the DT layer.

[en] 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)