Nuclear Diagnostics at the National Ignition Facility, 2013-2015

9th International Conference on Inertial Fusion Sciences and Applications

Yeamans, C.B.^1 ; Cassata, W.S.^1 ; Church, J.A.^1 ; Fittinghoff, D.N.^1 ; Gatu Johnson, M.^4 ; Gharibyan, N.^1 ; Határik, R.^1 ; Sayre, D.B.^1 ; Sio, H.W.^4 ; Bionta, R.M.^1 ; Bleuel, D.L.^1 ; Caggiano, J.A.^1 ; Cerjan, C.J.^1 ; Cooper, G.W.^6 ; Eckart, M.J.^1 ; Edwards, E.R.^5 ; Faye, S.A.^5 ; Forrest, C.J.^7 ; Frenje, J.A.^4 ; Glebov, V Yu^7 ; Grant, P.M.^1 ; Grim, G.P.^1 ; Hartouni, E.P.^1 ; Herrmann, H.W.^3 ; Kilkenny, J.D.^2 ; Knauer, J.P.^7 ; Mackinnon, A.J.^1 ; Merrill, F.E.^3 ; Moody, K.J.^1 ; Moran, M.J.^1 ; Petrasso, R.D.^4 ; Phillips, T.W.^1 ; Rinderknecht, H.G.^1 ; Schneider, D.H.G.^1 ; Sepke, S.M.^1 ; Shaughnessy, D.A.^1 ; Stoeffl, W.^1 ; Velsko, C.A.^1 ; Volegov, P.^3

Lawrence Livermore National Laboratory, Livermore

CA, United States^1

General Atomics, San Diego

CA, United States^2

Los Alamos National Laboratory, Los Alamos

NM, United States^3

Massachusetts Institute of Technology, Cambridge

MA, United States^4

University of California, Berkeley, Berkeley

CA, United States^5

University of New Mexico, Albuquerque

NM, United States^6

University of Rochester, Laboratory for Laser Energetics, Rochester

NY, United States^7

关键词: Independent measurement;    National ignition facility;    Neutron imaging systems;    Neutron time of flight;    Physical quantities;    Radiochemical analysis;    Recoil spectrometers;    Systematic uncertainties;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/717/1/012117/pdf
DOI  :  10.1088/1742-6596/717/1/012117

来源: IOP

【 摘 要 】

The National Ignition Facility (NIF) relies on a suite of nuclear diagnostics to measure the neutronic output of experiments. Neutron time-of-flight (NTOF) and neutron activation diagnostics (NAD) provide performance metrics of absolute neutron yield and neutron spectral content: spectral width and non-thermal content, from which implosion physical quantities of temperature and scattering mass are inferred. Spatially-distributed flange- mounted NADs (FNAD) measure, with nearly identical systematic uncertainties, primary DT neutron emission to infer a whole-sky neutron field. An automated FNAD system is being developed. A magnetic recoil spectrometer (MRS) shares few systematics with comparable NTOF and NAD devices, and as such is deployed for independent measurement of the primary neutronic quantities. The gas-Cherenkov Gamma Reaction History (GRH) instrument records four energy channels of time-resolved gamma emission to measure nuclear bang time and burn width, as well as to infer carbon areal density in experiments utilizing plastic or diamond capsules. A neutron imaging system (NIS) takes two images of the neutron source, typically gated to create coregistered 13-15 MeV primary and 6-12 MeV downscattered images. The radiochemical analysis of gaseous samples (RAGS) instrument pumps target chamber gas to a chemical reaction and fractionation system configured with gamma counters, allowing measurement of radionuclides with half-lives as short as 8 seconds. Solid radiochemistry collectors (SRC) with backing NAD foils collect target debris, where activated materials from the target assembly are used as indicators of neutron spectrum content, and also serve as the primary diagnostic for nuclear forensic science experiments. Particle time-of-flight (PTOF) measures compression-bang time using DT- or DD-neutrons, as well as shock bang-time using D3He-protons for implosions with lower x-ray background. In concert, these diagnostics serve to measure the basic and advanced quantities required to understand NIF experimental results.