First measurement of the 10B(α,n)13N reaction in an inertial confinement fusion implosion at the National Ignition Facility: Initial steps toward the development of a radiochemistry mix diagnostic

• Published in: Physics of plasmas 2022-05, Vol.29 (5)
• Main Authors: Lonardoni, D., Sauppe, J. P., Batha, S. H., Birge, Noah, Bredeweg, T., Freeman, M., Geppert-Kleinrath, V., Gooden, M. E., Hayes, A. C., Huang, H., Jungman, G., Keenan, B. D., Kot, L., Meaney, K. D., Murphy, T., Velsko, C., Yeamans, C. B., Whitley, H. D., Wilde, C., Wilhelmy, J. B.
• Format: Article
• Language: English
• Subjects: Ablative materials; Beryllium; Deuterium; Fluid mechanics; Hydrodynamics; Ignition; Inertial confinement fusion; Microprocessors; Nitrogen isotopes; Plasma physics; Radiation; Radiochemical analysis; Tritium
• ISSN: 1070-664X; 1089-7674
• DOI: 10.1063/5.0079676

We report the first measurement of the 10B(α,n)13N reaction in a polar-direct-drive exploding pusher (PDXP) at the National Ignition Facility (NIF). This work is motivated by the need to develop alternative mix diagnostics, radiochemistry being the focus here. The target is composed of a 65/35 at. % deuterium–tritium (DT) fill surrounded by a roughly 30 μm thick beryllium ablator. The inner portion of the beryllium ablator is doped with 10 at. % of 10B. Radiation-hydrodynamics calculations were performed in 1D to optimize both the remaining boron rho-R and the DT neutron yield. A charged-particle transport post-processor has been developed to study α-induced reactions on the ablator material. Results indicate a large 13N production from α-induced reactions on 10B, measurable by the radiochemical analysis of a gaseous samples system at the NIF. The PDXP target N201115-001 was successfully fielded on the NIF, and nitrogen from the 10B(α,n)13N reaction was measured. The 13N production yield, as well as the DT neutron yield, was, however, lower than expected. Some of the reduced yields can be explained by the oblate shape, but the ratios of the various radiochemical signals are not commensurate with expectations based on a simple reduction of the 1D results. Preliminary 2D radiation-hydrodynamics computations are consistent with the experimental measurements, and work is ongoing to extend the radiochemistry analysis into higher dimensions.