First D+D neutron image at the National Ignition Facility

First time-integrated neutron images of a deuterium gas filled capsule were obtained using arrival time gating with the Neutron Imaging System at the National Ignition Facility. Images exist from DT (deuterium and tritium mixture) filled capsules in several energy bands but only at the Omega laser h...

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Bibliographic Details
Published in:Physics of plasmas 2018-06, Vol.25 (6)
Main Authors: Volegov, P. L., Wilson, D. C., Dewald, E. L., Berzak Hopkins, L. F., Danly, C. R., Fatherley, V. E., Geppert-Kleinrath, V., Merrill, F. E., Simpson, R., Wilde, C. H., Fittinghoff, D. N., Casey, D. T., Grim, G. P., Ayers, M. J., Hatarik, R., Yeamans, C. B., Kruse, M. K. G., Sayre, D. B., Munro, D., Le Pape, S., Izumi, N., Batha, S. H.
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Bright spots
Carbon
Deuterium
Energy bands
ENGINEERING
Ignition
Image reconstruction
INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
Mathematical analysis
NUCLEAR PHYSICS AND RADIATION PHYSICS
Plasma physics
Tritium
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Summary:First time-integrated neutron images of a deuterium gas filled capsule were obtained using arrival time gating with the Neutron Imaging System at the National Ignition Facility. Images exist from DT (deuterium and tritium mixture) filled capsules in several energy bands but only at the Omega laser had DD (pure deuterium) filled capsules been imaged. A composite image was derived from an assembly of multiple penumbral neutron images using an iterative Maximum Likelihood reconstruction technique. This was compared with a simulated image from a radiation-hydrodynamic calculation. The observed image size, and shape agree, as do the primary DD, secondary DT neutron yields, and the burn duration. However, the observed cross-sectional profiles, although smaller in half width, extend outside the calculated, suggesting that deuterium has mixed outward into the carbon ablator. The observed X-ray image size (61 μm) is larger than the observed neutron image (51 μm). The calculations also reflect this. X-ray brightness includes carbon as well as deuterium emission. A bright spot, “meteor,” in the X-ray image is seen to move in time-gated images, but is not evident in the neutron image. It does not appear to degrade the neutron yield.
ISSN:1070-664X
1089-7674
DOI:10.1063/1.5029836