Abstract
The time-resolving Magnetic Recoil Spectrometer (MRSt) for the National Ignition Facility (NIF) has been identified by the US National Diagnostic Working Group as one of the transformational diagnostics that will reshape the way inertial confinement fusion (ICF) implosions are diagnosed. The MRSt will measure the time-resolved neutron spectrum of an implosion, from which the time-resolved ion temperature, areal density, and yield will be inferred. Top-level physics requirements for the MRSt were determined based on simulations of numerous ICF implosions with varying degrees of alpha heating, P2 asymmetry, and mix. Synthetic MRSt data were subsequently generated for different configurations using Monte-Carlo methods to determine its performance in relation to the requirements. The system was found to meet most requirements at current neutron yields at the NIF. This work was supported by the DOE and LLNL.
Highlights
Top-level physics requirements for the Magnetic Recoil Spectrometer (MRSt) were determined based on simulations of numerous inertial confinement fusion (ICF) implosions with varying degrees of alpha heating, P2 asymmetry, and mix
MRSt is an extension of the Magnetic Recoil Spectrometer (MRS) that has been identified by the US National Diagnostic Working Group as one of the transformational diagnostics that will reshape the way ICF implosions are diagnosed
We examined the correlations between these evolving implosion parameters and their time derivatives and how they depend on the alpha heating, P2 asymmetry, and mix
Summary
Neutron spectrometry is used routinely to diagnose burnaveraged properties of inertial confinement fusion (ICF) implosions, and in particular, the areal density (ρR), ion temperature (Ti), and neutron yield (Yn). The current Magnetic Recoil Spectrometer (MRS) is a neutron spectrometer fielded on OMEGA and the National Ignition Facility (NIF) that makes these measurements.. MRSt is an extension of the MRS that has been identified by the US National Diagnostic Working Group as one of the transformational diagnostics that will reshape the way ICF implosions are diagnosed.3 It is based on a deuterated plastic (CD) foil and an ion-optic system along with a time-resolving detector that will make measurements of ρR, Ti, and Yn as functions of time.. Critical to understanding the MRSt and its potential is determining its performance and evaluating whether it meets the current top-level physics requirements. Monte Carlo simulations of the MRSt system response combined with simulated neutron spectra were used to determine whether the system meets those requirements This was done at many different yield levels and for several different MRSt configurations.
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