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Title: The effect of turbulent kinetic energy on inferred ion temperature from neutron spectra

Measuring the width of the energy spectrum of fusion-produced neutrons from deuterium (DD) or deuterium-tritium (DT) plasmas is a commonly used method for determining the ion temperature in inertial confinement fusion (ICF) implosions. In a plasma with a Maxwellian distribution of ion energies, the spread in neutron energy arises from the thermal spread in the center-of-mass velocities of reacting pairs of ions. Fluid velocities in ICF are of a similar magnitude as the center-of-mass velocities and can lead to further broadening of the neutron spectrum, leading to erroneous inference of ion temperature. Motion of the reacting plasma will affect DD and DT neutrons differently, leading to disagreement between ion temperatures inferred from the two reactions. This effect may be a contributor to observations over the past decades of ion temperatures higher than expected from simulations, ion temperatures in disagreement with observed yields, and different temperatures measured in the same implosion from DD and DT neutrons. This difference in broadening of DD and DT neutrons also provides a measure of turbulent motion in a fusion plasma.
Authors:
 [1]
  1. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
Publication Date:
OSTI Identifier:
22304091
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; DEUTERIUM; ENERGY SPECTRA; IMPLOSIONS; INERTIAL CONFINEMENT; ION TEMPERATURE; KINETIC ENERGY; NEUTRON SPECTRA; PLASMA; SIMULATION; TRITIUM