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Bibliographic Details
Main Authors: Nguyen, Bao, Lawrence, Yousef, Wink, Christopher, Johnson, Timothy Mark, Vanderloo, Niels, Reichelt, Benjamin, Hennessy, Amber, Casey, Daniel Thomas, Schlossberg, Dave, Masters, Nathan, Milovich, Jose, Le, Ari, Craxton, Stephen, Johnson, Maria Gatu, Frenje, Johan
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2509.06999
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Table of Contents:
  • The Magnetic Recoil Spectrometer (MRS) on the National Ignition Facility is used to measure the neutron spectrum from deuterium-tritium fueled inertial confinement fusion implosions via n-d elastic scattering and magnetic dispersion of recoil deuterons. From the MRS-determined neutron spectrum, the yield ($Y_n$), apparent ion temperature ($T_i$) and areal density ($ρR$) are determined. However, anomalous energy modulations in recoil deuterons have been observed in several high-yield indirect drive experiments ($Y_n\sim10^{16}-10^{18}$). These observations raise concerns about their potential impact on the MRS-inferred performance metrics. Analytic calculations and particle-in-cell simulations are used to examine the possible beam-plasma instabilities, which indicate the two-stream instability as the driving mechanism behind energy modulations. Based on a statistical analysis of synthetic deuteron spectra, the modulations-induced errors are found to be within the errors of the determined $Y_n$, $T_i$ and $ρR$ values and thus do not have a significant impact on the MRS measurement.