Methods pioneered using the Laboratory for Laser Energetics’ OMEGA laser system show potential for sparking fusion on a larger scale.
Researchers at the University of Rochester’s Laboratory for Laser Energetics (LLE) have led experiments showcasing an efficient “spark plug” for direct-drive approaches to inertial confinement fusion (ICF). In a pair of studies featured in breakthrough at NIF in achieving fusion ignition—a fusion reaction that creates a net gain of energy from the target.
Achievements and Future Prospects
“Generating more fusion energy than the internal energy content of where the fusion takes place is an important threshold,” says lead author of the first paper Connor Williams ’23 Ph.D. (physics and astronomy), now a staff scientist at Sandia National Labs in radiation and ICF target design. “That’s a necessary requirement for anything you want to accomplish later on, such as burning plasmas or achieving ignition.”
By showing they can achieve this level of implosion performance with just 28 kilojoules of laser energy, the Rochester team is excited by the prospect of applying direct-drive methods to lasers with more energy. Demonstrating a spark plug is an important step, however, OMEGA is too small to compress enough fuel to get to ignition.
“If you can eventually create the spark plug and compress fuel, direct drive has a lot of characteristics that are favorable for fusion energy compared to indirect-drive,” says Varchas Gopalaswamy ’21 Ph.D. (mechanical engineering), the LLE scientist who led the second study that explores the implications of using the direct-drive approach on megajoule-class lasers, similar to the size of the NIF. “After scaling the OMEGA results to a few megajoules of laser energies, the fusion reactions are predicted to become self-sustaining, a condition called ‘burning plasmas.’”
Gopalaswamy says that direct-drive ICF is a promising approach for achieving thermonuclear ignition and net energy in laser fusion.
Technological Innovations and Collaborations
“A major factor contributing to the success of these recent experiments is the development of a novel implosion design method based on statistical predictions and validated by DOI: 10.1038/s41567-023-02363-2
“Demonstration of a hydrodynamically equivalent burning plasma in direct-drive inertial confinement fusion” by V. Gopalaswamy, C. A. Williams, R. Betti, D. Patel, J. P. Knauer, A. Lees, D. Cao, E. M. Campbell, P. Farmakis, R. Ejaz, K. S. Anderson, R. Epstein, J. Carroll-Nellenbeck, I. V. Igumenshchev, J. A. Marozas, P. B. Radha, A. A. Solodov, C. A. Thomas, K. M. Woo, T. J. B. Collins, S. X. Hu, W. Scullin, D. Turnbull, V. N. Goncharov, K. Churnetski, C. J. Forrest, V. Yu. Glebov, P. V. Heuer, H. McClow, R. C. Shah, C. Stoeckl, W. Theobald, D. H. Edgell, S. Ivancic, M. J. Rosenberg, S. P. Regan, D. Bredesen, C. Fella, M. Koch, R. T. Janezic, M. J. Bonino, D. R. Harding, K. A. Bauer, S. Sampat, L. J. Waxer, M. Labuzeta, S. F. B. Morse, M. Gatu-Johnson, R. D. Petrasso, J. A. Frenje, J. Murray, B. Serrato, D. Guzman, C. Shuldberg, M. Farrell and C. Deeney, 5 February 2024, Nature Physics.
DOI: 10.1038/s41567-023-02361-4
The Rochester experiments required a highly coordinated effort between a large number of scientists, engineers, and technical staff to operate the complex laser facility. They collaborated with researchers from the