Daniel Schirmann, Luc Bianchi, Patrick Chadeyron, Roger Courchinoux, Henry Patrick Jacquet, Francois Jequier, Anne Fornier, Jean Claude Gomme, Olivier Heuze, Thierry Lonjaret, Gerard Sibille, Jean Pierre Thebault and the LMJ project team
Commissariat a l'Energie Atomique
Centre d'Etudes de Bruyeres le Chatel
Ma”trise d'Oeuvre Principale
BP 12
91680 Bruyeres-le-Chatel Cedex (F)
The Laser Megajoule (LMJ) is the project equivalent in France to the National Ignition Facility project (NIF) in USA. The target area is designed to withstand the maximum threats imposed by large emissions of neutrons, x-rays and debris due to the explosion of high fusion yield targets (20 MJ).
Prediction calculations of the x-ray threats on the final optics, on the first wall and diagnostics are detailed. We show that the first wall has to be protected by refractive materials. We also show that high velocity shrapnels generated by neutron, x-ray and ion deposition in the materials close to the target could also be a threat for the first wall, final optics, diagnostics and have to be minimized.
Phebus laser facility is used as a testbed to study both the behavior of first wall material candidates to x-rays, to study the generation of the shrapnels and their effects, to validate shock absorber structures allowing to protect the instruments close to the target against the impulse due to the energy deposition.