Results from neutron imaging of ICF experiments at NIF

8th International Conference on Inertial Fusion Sciences and Applications

Merrill, F.E.^1,2 ; Danly, C.R.^1 ; Fittinghoff, D.N.^2 ; Grim, G.P.^1 ; Guler, N.^1 ; Volegov, P.L.^1 ; Wilde, C.H.^1

Los Alamos National Laboratory, PO Box 1663, Los Alamos

NM, United States^1

Livermore National Laboratory, PO Box 808, Livermore

CA, United States^2

关键词: 14 MeV neutrons;    Burning plasmas;    Detection system;    National ignition facility;    Neutron imaging;    Performance metrics;    Source distribution;    Two dimensional distribution;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/688/1/012064/pdf
DOI  :  10.1088/1742-6596/688/1/012064

来源: IOP

【 摘 要 】

In 2011 a neutron imaging diagnostic was commissioned at the National Ignition Facility (NIF). This new system has been used to collect neutron images to measure the size and shape of the burning DT plasma and the surrounding fuel assembly. The imaging technique uses a pinhole neutron aperture placed between the neutron source and a neutron detector. The detection system measures the two-dimensional distribution of neutrons passing through the pinhole. This diagnostic collects two images at two times. The long flight path for this diagnostic, 28 m, results in a chromatic separation of the neutrons, allowing the independently timed images to measure the source distribution for two neutron energies. Typically one image measures the distribution of the 14 MeV neutrons, and the other image measures the distribution of the 6-12 MeV neutrons. The combination of these two images has provided data on the size and shape of the burning plasma within the compressed capsule, as well as a measure of the quantity and spatial distribution of the cold fuel surrounding this core. Images have been collected for the majority of the experiments performed as part of the ignition campaign. Results from this data have been used to estimate a burn-averaged fuel assembly as well as providing performance metrics to gauge progress towards ignition. This data set and our interpretation are presented.