A neutron time-of-flight (nTOF) system has been implemented at the largest laser facility in China. The nTOF system is used to measure neutron spectra in inertial confinement fusion experiments. The nTOF system consists of 11 fast plastic scintillation detectors. The detectors employed three designs to measure neutron yield, ion temperature, and neutron bang time. The nTOF system is capable of measuring the primary neutron yield from 10 to 10, secondary DT neutron yield from 10 to 10, and ion temperature and neutron bang time yields from 10 to 10. The accuracies of the nTOF system are about 10% for neutron yield and ion temperature measurements and better than 60 ps for neutron bang time measurements. The nTOF system has become one of the most important diagnostics for implosions, and it is used for more than 200 shots per year.
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http://dx.doi.org/10.1063/1.5109711 | DOI Listing |
Rev Sci Instrum
August 2024
Sandia National Laboratories, 1515 Eubank SE, Albuquerque, New Mexico 87185, USA.
The neutron time-of-flight (nToF) diagnostic technique has a lengthy history in Inertial Confinement Fusion (ICF) and High Energy Density (HED) Science experiments. Its initial utility resulted from the simple relationship between the full width half maximum of the fusion peak signal in a distant detector and the burn averaged conditions of an ideal plasma producing the flux [Lehner and Pohl, Z. Phys.
View Article and Find Full Text PDFRev Sci Instrum
July 2024
Plasma Science and Fusion Center, Massachusetts Institute of Technology, 167 Albany St., Cambridge, Massachesetts 02139, USA.
3D asymmetries are major degradation mechanisms in inertial-confinement fusion implosions at the National Ignition Facility (NIF). These asymmetries can be diagnosed and reconstructed with the neutron imaging system (NIS) on three lines of sight around the NIF target chamber. Conventional tomographic reconstructions are used to reconstruct the 3D morphology of the implosion using NIS [Volegov et al.
View Article and Find Full Text PDFRev Sci Instrum
April 2023
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
The performance of modern laser-driven inertial confinement fusion (ICF) experiments is degraded by contamination of the deuterium-tritium (DT) fuel with high-Z material during compression. Simulations suggest that this mix can be described by the ion temperature distribution of the implosion, given that such contaminants deviate in temperature from the surrounding DT plasma. However, existing neutron time-of-flight (nTOF) diagnostics only measure the spatially integrated ion temperature.
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January 2021
Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299, USA.
A traditional neutron time-of-flight (nTOF) detector used in inertial confinement fusion consists of a scintillator coupled with a photomultiplier tube (PMT). The instrument response function (IRF) of such a detector is dominated by the scintillator-light decay. In DT implosions with neutron yield larger than 10, a novel detector consisting of a microchannel-plate (MCP) photomultiplier tube in a housing without a scintillator (PMT nTOF) can be used to measure DT yield, ion temperature, and neutron velocity.
View Article and Find Full Text PDFRev Sci Instrum
February 2020
Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang, Sichuan 621900, China.
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