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The Megajoule Laser

The Megajoule Laser facility (LMJ) is a key component of CEA's Simulation Program. Its purpose is to study, at a very small scale, the behavior of materials under extreme conditions similar to those reached during the operation of nuclear weapons. The LMJ is designed to deliver, in a few billionths of a second, more than one million joules of light energy to targets measuring a few millimeters in size. It was officially commissioned on October 23, 2014, with the performance of a first series of experiments.

laser bay
LEFT - The LMJ in December 2013. MIDDLE - One of the four laser halls.
RIGHT - The LMJ's experimental chamber, installed in November 2006. © CEA

Validation of the numerical simulation chain

The computer codes used to simulate the nuclear operation of weapons contain a vast array of theoretical models and physical data (equations of state, effective neutron cross-sections , opacities) that are valid in well known ranges of applicability (boundary of validity).

The LMJ will be used in particular to:

  • Validate theoretical models and physical data describing the behavior of nuclear weapons, and to verify that all phenomena involved are taken into account by modeling.
  • Conduct experiments involving the sequencing and overlapping of these models. These experiments are essential to demonstrate that physicists effectively master the right coverage of computer codes used to simulate the operation of nuclear weapons.

Inertial confinement fusion (ICF)

The LMJ is designed to be able to achieve inertial confinement fusion.

Certification of new teams of physicists

High-resolution visual representation of laser target calculation.
High-resolution visualization of a laser target calculation. © CEA

The LMJ is essential to ensure that DAM physicists, who are responsible for guaranteeing the safety and reliability of nuclear weapons, indeed have the necessary high level of skills. They must be able to:

  • Design a relevant experiment for validating an elementary physical model.
  • Define the range of applicability of a model in order to very its limits by comparing predicted and experimental results.
  • Design more complex experiments involving a sequence of physics phenomena.
  • Demonstrate their ability to guarantee.

For more information:

MàJ: 08/09/2014
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