Hot-spot model for inertial confinement fusion implosions with an applied magnetic field

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Main Authors: Spiers, R. C., Bose, A., Frank, C. A., Lahmann, B., Moody, J. D., Sio, H., Strozzi, D. J.
Format: Preprint
Published: 2025
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author Spiers, R. C.
Bose, A.
Frank, C. A.
Lahmann, B.
Moody, J. D.
Sio, H.
Strozzi, D. J.
author_facet Spiers, R. C.
Bose, A.
Frank, C. A.
Lahmann, B.
Moody, J. D.
Sio, H.
Strozzi, D. J.
contents Imposing a magnetic field on inertial confinement fusion (ICF) implosions magnetizes the electrons in the compressed fuel; this suppresses thermal losses which increases temperature and fusion yield. Indirect-drive experiments at the National Ignition Facility (NIF) with 12 T and 26 T applied magnetic fields demonstrate up to $40\%$ increase in temperature, 3x increase in fusion yield, and indicate that magnetization alters the radial temperature profile [J.D. Moody $\mathrm{\textit{et al.}}$, Phys. Rev. Lett. $\mathrm{\textbf{129}}$, 195002 (2022), B. Lahmann et al., APS DPP 2022]. In this work, we develop a semi-analytic hot-spot model which accounts for the 2D Braginskii anisotropic heat flow due to an applied axial magnetic field. Firstly, we show that hot-spot magnetization alters the radial temperature profile, increasing the central peakedness which is most pronounced for moderately magnetized implosions (with 8-14 T applied field), compared to both unmagnetized (with no applied field) and highly magnetized (with 26 T or higher applied field) implosions. This model explains the trend in the experimental data which finds a similarly altered temperature profile in the 12 T experiment. Next, we derive the hot-spot model for gas-filled (Symcap) implosions, accounting for the effects of magnetization on the thermal conduction and in changing the radial temperature (and density) profiles. Using this model, we compute predicted central temperature amplification and yield enhancement scaling with the applied magnetic field. The central temperature fits the experimental data accurately, and the discrepancy in the yield suggests a systematic (independent of applied field) degradation such as mix, and additional degradation in the reference unmagnetized shot such as reduced laser drive, increased implosion asymmetry, or the magnetic field suppressing ablator mixing into the hot-spot.
format Preprint
id arxiv_https___arxiv_org_abs_2503_00186
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Hot-spot model for inertial confinement fusion implosions with an applied magnetic field
Spiers, R. C.
Bose, A.
Frank, C. A.
Lahmann, B.
Moody, J. D.
Sio, H.
Strozzi, D. J.
Plasma Physics
Imposing a magnetic field on inertial confinement fusion (ICF) implosions magnetizes the electrons in the compressed fuel; this suppresses thermal losses which increases temperature and fusion yield. Indirect-drive experiments at the National Ignition Facility (NIF) with 12 T and 26 T applied magnetic fields demonstrate up to $40\%$ increase in temperature, 3x increase in fusion yield, and indicate that magnetization alters the radial temperature profile [J.D. Moody $\mathrm{\textit{et al.}}$, Phys. Rev. Lett. $\mathrm{\textbf{129}}$, 195002 (2022), B. Lahmann et al., APS DPP 2022]. In this work, we develop a semi-analytic hot-spot model which accounts for the 2D Braginskii anisotropic heat flow due to an applied axial magnetic field. Firstly, we show that hot-spot magnetization alters the radial temperature profile, increasing the central peakedness which is most pronounced for moderately magnetized implosions (with 8-14 T applied field), compared to both unmagnetized (with no applied field) and highly magnetized (with 26 T or higher applied field) implosions. This model explains the trend in the experimental data which finds a similarly altered temperature profile in the 12 T experiment. Next, we derive the hot-spot model for gas-filled (Symcap) implosions, accounting for the effects of magnetization on the thermal conduction and in changing the radial temperature (and density) profiles. Using this model, we compute predicted central temperature amplification and yield enhancement scaling with the applied magnetic field. The central temperature fits the experimental data accurately, and the discrepancy in the yield suggests a systematic (independent of applied field) degradation such as mix, and additional degradation in the reference unmagnetized shot such as reduced laser drive, increased implosion asymmetry, or the magnetic field suppressing ablator mixing into the hot-spot.
title Hot-spot model for inertial confinement fusion implosions with an applied magnetic field
topic Plasma Physics
url https://arxiv.org/abs/2503.00186