A Short-Pulse, Laser-Driven Neutron Source for Stockpile Stewardship Science
Gerald Williams | 21-FS-021
Neutron sources are critical tools in the investigation of matter by accessing objects that x rays cannot penetrate and are currently indispensable tools in the fields of nondestructive evaluation, material damage, and aging investigations critical to the NNSA mission. Preliminary short-pulse laser-driven neutron source (SP-LDNS) experiments have demonstrated favorable yields that could meet the needs of NNSA in the arenas of high-energy-density science (HEDS), dynamic materials, and stockpile stewardship science. Through analytic and computational modeling, this project assessed the feasibility of a compact, high-flux, and scalable SP-LDNS using next-generation high-energy and high-repetition-rate laser architectures that are currently planned or in development. Several areas were identified to have needs for which laser-based sources could have transformative capabilities including radiography (tomography), nuclear resonance spectroscopy, and fission product yields. A key finding of the project was that the most impactful near-term application is the development of a simultaneous x-ray and neutron radiographic capability. Analytic scaling predicted that the neutron yield from next-generation laser facilities would meet or exceed those from prototype machines being developed for stockpile stewardship programs while providing the unique characteristics of a laser-driven source.
The ability of MeV neutrons to penetrate very high areal density objects while, in particular, maintaining a high sensitivity to hydrogen-containing compounds is essential to several critical NNSA mission applications such as imaging aging-related defects in the stockpile, and resolving the shape of composite objects under dynamic compression, which are primary objectives for several programmatic efforts. Combining these techniques to provide both an x-ray and neutron (or multimodal) radiograph via a source concept that scales to multiple axis for tomography, would enable a revolutionary imaging capability for a more complete reconstruction of the interrogated object.
This work directly addresses R&D priorities highlighted in the Lawrence Livermore National Laboratory FY21 Investment Strategy for Stockpile Stewardship. This project will maintain the Laboratory's leadership in fundamental physics that impacts applications critical to mission needs. Developing novel neutron sources has wide applicability to NNSA mission needs. This work contributes to maintaining U.S. preeminence in laser and neutron science. It has established new collaborations between laser developers in the Advanced Photon Technologies Group in the National Ignition Facility and Photon Science Principal Associate Directorate, static and dynamic radiography end-users within the Engineering Directorate, and the Weapons and Complex Integration Principal Associate Directorate, and identified new opportunities for the long-term future needs of NNSA for stockpile support.
Publications, Presentations, and Patents
Williams, Jackson. Lawrence Livermore National Laboratory Joint High Energy Density Summer Scholars Idea Day, 16 Feb 2021.
Williams, Jackson. Nuclear and Chemical Sciences Division LDRD Symposium, 9 Feb 2021.
Williams, Jackson. LDRD ER Proposal, 17 June 2021.
Ryan, Charlotte, National Ignition Facility & Photon Science summer student meeting, 18 June 2021.