Laser-on-Wheels: A Study to Determine Feasibility
Christopher Wehrenberg | 21-FS-010
The "Laser-on-Wheels" (LoW) vision is to create a portable laser capable of being deployed at a range of facilities to augment and revolutionize experimental approaches. Representing a paradigm shift in experimental capabilities, a portable high-powered laser would combine laser driven neutrons, x rays, or a flexible pressure driver with traditionally singular experimental capabilities throughout the NNSA and DOE complex such as gas guns, x-ray free-electron lasers, or accelerators. In this one-year project, the feasibility of a laser on wheels, and the requirements for identified applications that could benefit from a compact, portable, kilojoule- (kJ-) class laser were studied. To achieve the needed level of facility integration, the laser itself would be miniaturized to the extent that it would fit on a truck and be able to be fielded and aligned at a new site in the span of a few weeks. A rough estimate of cost, size, weight, portability, and hence feasibility of the concept was examined.
Several broad classes of laser systems, defined by pulse duration, pulse energy, and repetition rate, were evaluated for portability. The practical limits on portability are set mainly by the energy per pulse, the dominant factor in determining laser size, and the pulse duration, which greatly affects the alignment and fielding time. Lasers with less than a few kJ per pulse and pulse durations greater than 100 picoseconds (ps) can feasibly be made portable. A short pulse laser system (<100 ps pulse length) could be made semi-portable by fielding multiple but stationary laser compressors at various sites while the main drive laser is transported from site to site. A few key applications, such as laser driven neutrons and x rays, and a flexible pressure driver, were selected for further discussion and requirements development. A portable 1 to 2 kJ laser system would have the largest number of applications and would cost ~$30–40M, while stationary compressors to enable short pulse operations would cost ~$10M at each site.
Current Stockpile Stewardship Programs rely heavily on experimental data to develop and validate physics and computational models. The innovation of a portable high-energy laser that can be brought to other facilities opens new opportunities and flexibility for high-energy-density (HED) and weapons science. As cited in the 2020 Lawrence Livermore National Laboratory Investment Strategy, "Investments are needed to develop short-pulse laser-driven radiation sources. This technology could affect a paradigm shift that accelerates stockpile-stewardship-related HED science and the emergence of laser-driven radiation sources for a host of national security applications." Furthermore, the scientific needs as identified by this study will provide important input to developing the next generation of laser drivers. The unique capabilities enabled by LoW would foster collaborations and academic partnerships, helping to address the critical recruiting challenges that will be required to maintain the world-class workforce needed to execute NNSA missions.