Inertial fusion with the LMJ

The progress of the construction of very large laser facilities LMJ and NIF enables the prediction of inertial fusion achievement. These facilities will open new fields for research: the high energy density physics. Pressures of several 100 Mbars and temperatures of several 100 eV will be reached. Measurements of material properties (EOS and opacities) which have been demonstrated on current or former facilities will be possible at these never reached conditions. Pure hydrodynamics (instabilities) and radiative hydrodynamics astrophysical issues will be addressed. However, ignition and gain as a first proof of Inertial Confinement Fusion is a primary goal. The indirect drive route to inertial fusion has been prepared for many years by CEA (Commissariat a l'Energie Atomique). The last ten years were imprinted by a close collaboration between CEA and US-DOE in both the areas of facilities R&D and ignition target physics. The scientific issues are well known: the propagation of laser light through the very long plasma created inside the hohlraum has to be understood and mastered to be sure that less than 10% of laser energy will be backscattered by parametric instabilities. On the other hand, the stability of the capsule implosion has to be matched with the fabrication surface finish so as to avoid shell destruction and extinction of the central hot spot. Recent advances at CEA have allowed a better confidence of reaching ignition using the facility previously specified. These works used the CEA computing capability combined with plasma experiments on existing lasers facilities. Ignition achievement also supposes the realization of suitable cryogenic targets. CEA began the construction of the Laser Megajoule (LMJ), a 240-beam laser facility, at the CEA Laboratory CESTA near Bordeaux. The LMJ is designed to deliver 2 MJ of 0.35 mu m light to targets for high energy density physics experiments. Four beams were operated for plasma experiments on the Ligne d'Integration Laser (LIL) at CESTA, for the end of 2004, meeting the specifications for LMJ. The realization phase of the LMJ facility was initiated in March 2003 with the start of construction of the building and the target chamber.