Quick Shot
Improving Polar-Direct-Drive Fusion Neutron Sources
May 17, 2021
Emma Garcia, Stephen Craxton, Yujia Yang, Patrick McKenty, and Charles Yeamans
Scientists and students at LLE are collaborating with scientists from Lawrence Livermore National Laboratory (LLNL) to improve polar-direct-drive (PDD) neutron sources at the National Ignition Facility (NIF). This work has grown out of early high-neutron-yield experiments done on the OMEGA Laser System, commissioned in 1996. At that time, OMEGA established a laser-produced, record neutron yield of 1.4 × 1014, which stood for almost 15 years until being surpassed by early NIF cryogenic experiments. The research was revived in 2009 to provide a simple and flexible, room-temperature neutron-source platform used in the commissioning of a myriad of neutron-based diagnostics for the NIF. The effort, spearheaded by Patrick McKenty and Stephen Craxton of LLE and Charles Yeamans of LLNL, produced a wide range of prescribed yields from 1 × 1012 up through the current warm target record of 1 × 1016. The design work of undergraduate students Emma Garcia and Yujia Yang (former participants in LLE’s Summer High School Research Program) in determining the most efficient and uniform beam defocusing and placement of the NIF PDD laser beams onto the various size capsules has been critical in this effort. Recent national program emphasis has been on developing high-yield (up to 1 × 1017) sources and the team will continue its effort using increased laser energy and larger-diameter targets until the goal is in hand. Read more of this recent collaboration in the following links.