Laser Mégajoule

Laser Mégajoule (LMJ) is a large laser-based inertial confinement fusion (ICF) research device being built near Bordeaux, in France by the French nuclear science directorate, CEA. Laser Mégajoule plans to deliver about 1.8 MJ of laser energy to its targets, making it about as energetic as its US counterpart, the National Ignition Facility (NIF). Laser Mégajoule is the largest ICF experiment to be built outside the US, where ICF research has been strongly related to nuclear weapons research. Likewise, Laser Mégajoule's primary tasks will be refining fusion calculations for France's own nuclear weapons.

Laser Mégajoule uses a series of 176 laser beamlines. Each beamline contains two main glass amplifiers, which are optically pumped using xenon flashlamps. A "feeder" laser beam is fed via optical fiber into each of the beamlines where it travels through the two amplifiers. In order to extract more power from the amplifiers, which are not particularly efficient in transmitting power to the beam, the laser pulse is sent through the amplifiers twice by an optical switch in front of a mirror. At the other end of the beamline a deformable mirror is used to remove imperfections in the wavefront.