Spot size measurement of a deuterium–tritium dense plasma focus using neutron radiography

Tafoya, Landon Reese; Geppert-Kleinrath, Verena; Allison, Jason Clark; Baker, Stuart A.; Bundgaard, J.; Freeman, Matthew Stouten; Hayes-Sterbenz, Anna Catherine; Jungman, Gerard; Li, Hui; Li, Shengtai; Lowe, D.; Tybo, J.; Wilde, C.

doi:10.1063/5.0187567

Spot size measurement of a deuterium–tritium dense plasma focus using neutron radiography

Journal Article · Thu May 02 04:00:00 EDT 2024 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/5.0187567· OSTI ID:2367512

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Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Nevada National Security Site (NNSS), Las Vegas, NV (United States)

Neutron radiography is a technique uniquely suited to applications in nuclear diagnostics, non-destructive testing, and subcritical experiments. The spatial resolution of neutron radiographs is degraded by optical blur in the imaging system and the neutron source size, where the ideal source is point-like to optimize the point-spread function. A potential neutron source for radiography is the dense plasma focus (DPF), a coaxial Z-pinch that produces thermonuclear and beam-target neutrons. To assess if the source size is suitable for radiography, a neutron imaging system was used to measure the source size of the 4 MA Sodium DPF at the Nevada National Security Site operating with deuterium–tritium gas-fill. The source size was measured using the edge-spread function of tungsten objects, each having a rolled (convex) edge. The spot size was found to be 7–12 mm full-width at half-max (FWHM) assuming a Gaussian source, though comparison is presented for Lorentzian and Bennett distributions. The average FWHM was found to be 8.6 ± 1.2 mm vertically and 10.8 ± 1.2 mm horizontally with respect to the image plane, averaging over varied edges and alignments. The results were sensitive to source alignment and edge metrology, which introduced notable uncertainties. These results are consistent with separate experimental measurements as well as magnetohydrodynamics simulations of this DPF, which suggest that neutron production can originate from pinches ∼5–7 mm off-axis. These results suggest that the DPF should be used for radiography at low magnification (M < 1) where spot size does not dominate spatial blur.

View Accepted Manuscript (DOE)

Research Organization:: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Organization:: USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)

Grant/Contract Number:: 89233218CNA000001; NA0003624

OSTI ID:: 2367512

Report Number(s):: LA-UR--23-32800

Journal Information:: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 5 Vol. 95; ISSN 0034-6748

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

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