2025/09/04 by Bao Nguyen, Y. Lawrence, Nguyen, Bao +27
Engineering · Physics and Astronomy · #FOS: Physical sciences #Laser-Plasma Interactions and Diagnostics #Laser-induced spectroscopy and plasma #Magnetic confinement fusion research #Plasma Physics (physics.plasm-ph)
paper · pdf · doi:10.48550/arxiv.2509.06999
openalex publication_date 2025/09/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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 (Yn), apparent ion temperature (Ti) and areal density (ρR) are determined. However, anomalous energy modulations in recoil deuterons have been observed in several high-yield indirect drive experiments (Yn∼1016-1018). 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 Yn, Ti and ρR values and thus do not have a significant impact on the MRS measurement.