Lawrence Livermore National Laboratory's National Ignition Facility (NIF) recently set a new record by firing 2.15 megajoules of energy into its target chamber -- a 10% increase over the previous mark and a 15% improvement over its design specification.
The record met a National Nuclear Security Administration (NNSA) Level 2 Milestone for 2018. NIF is the world's largest and most powerful laser, and is funded by the NNSA to support the Stockpile Stewardship Program.
"NIF's users are always asking to use more energy in their experiments, because higher energies enhance the science NIF can deliver in support of the stewardship program," said NIF director Mark Herrmann. "These results mark a major step toward increasing NIF's energy and power capability. This demonstration serves as the first step on a path that could allow NIF to operate at substantially higher energies than ever envisioned during NIF's design."
The NIF experiment effectively demonstrated the highest energy the laser could safely deliver with its current optics and configuration. By increasing its energy limit, the NIF can expand the parameter space for stewardship experiments and serve as a vital boost to the pursuit of ignition.
A similar demo laser campaign was performed on the NIF last year. Published in Nuclear Fusion, the campaign utilized four NIF beams to study performance limits and operational costs against predictive models. Efforts were successful in producing the highest energies at the time and set the stage for the delivery of 2.1 megajoules on the 192-beam system.
"The successful 2.1 MJ demonstration is the result of a sustained science and technology investment in NIF and fundamental understanding of optical damage, much of which has been supported by Laboratory Directed Research & Development (LDRD) and other institutional programs," said Jeff Wisoff, NIF and Photon Science Principal associate director.
The NIF laser uses tens of thousands of precision optical components, including lenses, laser glass slabs, mirrors and frequency conversion crystals to amplify the 192 laser beams to a target in the 10-meter target chamber.
Due to constant improvements, these optics are at the cutting edge of material science, and play an important role in raising the laser's energy thresholds. Recent discoveries have reduced the level of damage initiation in the optics and led to a reduced cost to mitigate existing damage spots.
NIF is currently working with LLNL's ignition program to execute the first ignition experiments that utilize enhanced energy capabilities during summer. This is the first step toward extending NIF's energy output to improve the NIF mission space and its contributions to the Stockpile Stewardship Program, officials said.