In a decade, Exail has become the sole supplier of radiation resistant diagnostics optical fibers, enabling the National Ignition Facility (LLNL NIF) in the US and the Laser Megajoule (CEA LMJ) in France to reach new limits in terms of performance.
In December 2022, the team of Lawrence Livermore National Laboratory (LLNL NIF) performed the first fusion ignition experiment – with more energy released from the fusion reactions (3.15 MJ) than the laser energy (2.05 MJ) used to trigger them. France built its equivalent of the LLNL-NIF, the Megajoule Laser (CEA LMJ). Commissioned at the end of 2014, it is primarily used to ensure the safety and reliability of nuclear weapons for deterrence. Accurate diagnostics are crucial to reach thermonuclear gain fusion with high energy lasers. The teams of both facilities have had strong interactions over the years, facing similar challenges and sharing their technical knowledge and competency, in particular around diagnostics optical fibers able to resist intense levels of radiation.
The CEA LMJ and LLNL NIF are huge facilities: hundreds of pulse laser beams, with a duration of around a nanosecond, are targeted on a millimeter-sized microsystem. Once combined, the laser beams reach an ultraviolet laser energy of 1.2 MegaJoule (more than 2 MegaJoules at LLNL NIF) in a luminous flash producing hundreds of terawatts (thousand billion Watts). By accurately synchronizing the laser beams, it is possible to carry out extremely complex laser-matter interaction experiments with an incredibly high level of homogeneous compression.
The target is designed to reproduce, after having received the MegaJoule of energy, a phenomenon of the same nature as that occurring in weapons, or in the core of stars. The most complex experiments are those leading to thermonuclear gain fusion (the nuclear energy released by the fusion reactions is greater than the laser energy invested to trigger these reactions) by inertial confinement of a deuterium-tritium mixture in the micro-target. Creating and accurately controlling such extreme physical parameters also opens the doors for new physics. “We receive more and more requests from scientific researchers wanting to use our laser facility to explore laser-matter interactions” Nicolas Beck, research engineer at CEA LMJ.
The extremely accurate synchronization of the pulse laser beams is made possible by measurement diagnostics, which are specialized state-of-the-art measuring instruments collecting data from the experiment in real-time.