High yield polar direct drive fusion neutron sources at the National Ignition Facility
- 10 February 2021
- journal article
- research article
- Published by IOP Publishing in Nuclear Fusion
- Vol. 61 (4), 046031
- https://doi.org/10.1088/1741-4326/abe4e6
Abstract
Polar direct drive neutron source experiments were performed at the National Ignition Facility showing substantial improvement in total neutron yield and efficiency of conversion of laser energy to fusion output. Plastic capsules 3–4 mm in diameter were filled with 1.5 mg/cc of deuterium–tritium (DT) fuel and imploded with laser beam pointing and defocus designed to compensate for polar asymmetry introduced by the facility beam entrance angles. Radiation-hydrodynamics simulations were employed to optimize the multi-dimensional laser and target parameter space, within facility and target fabrication constraints. Ensembles of 1D simulations tuned to match the outputs of early shots in the series were used to design subsequent shots in the series. This allowed the later shots to be designed based on empirically motivated sensitivities to laser and target input parameters, while eliminating the need to explicitly model phenomena such as hydrodynamic instabilities and nonlinear laser–plasma interactions. One experiment with a 3.0 mm diameter CH capsule produced 13.6 kJ (4.81 × 1015 DT neutrons) from a laser input below the NIF optics damage threshold at 585 kJ, 328 TW. Two experiments with 4.0 mm capsules produced 31.3 and 33.6 kJ of fusion output (1.11 × 1016 and 1.19 × 1016 DT neutrons) with 1.10 MJ, 390 TW and 1.26 MJ, 425 TW of laser input, respectively.Keywords
Funding Information
- U.S. Department of Energy (DE-AC52-07NA27344)
This publication has 70 references indexed in Scilit:
- A study of ALE simulations of Rayleigh–Taylor instabilityComputer Physics Communications, 2001
- Observation of Energy Transfer between Frequency-Mismatched Laser Beams in a Large-Scale PlasmaPhysical Review Letters, 1996
- Improved formulas for fusion cross-sections and thermal reactivitiesNuclear Fusion, 1992
- Effect of laser illumination nonuniformity on the analysis of time-resolved x-ray measurements in uv spherical transport experimentsPhysical Review A, 1987
- Laser Fusion Experiments at 4 TWPhysical Review Letters, 1978
- Preheat Effects on Microballoon Laser-Fusion ImplosionsPhysical Review Letters, 1975
- Multi-group diffusion of energetic charged particlesNuclear Fusion, 1975
- Indications of Strongly Flux-Limited Electron Thermal Conduction in Laser-Target ExperimentsPhysical Review Letters, 1975
- Fusion neutron energies and spectraPlasma Physics, 1973
- Laser Compression of Matter to Super-High Densities: Thermonuclear (CTR) ApplicationsNature, 1972