Application of an energy-dependent instrument response function to analysis of nTOF data from cryogenic DT experiments

Mohamed, Z. L.; Mannion, O. M.; Knauer, J. P.; Forrest, C.; Glebov, V. Yu.; Stoeckl, C.; Romanofsky, M. H.

doi:10.1063/5.0043647

Cited by 4 publications

(1 citation statement)

References 16 publications

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“…Other diagnostics on OMEGA have shown evidence for a mode 1 asymmetry. Notably, analysis of neutron time of flight (nTOF) data on OMEGA cryogenic experiments have revealed a ρR asymmetry consistent with lower ρR on the south pole of the target and higher ρR on the north pole [7], consistent with the flow measurement presented here.…”

Section: Systematic Anomalies In Current Best-setup Omega Implosionssupporting

confidence: 85%

3D simulations of inertial confinement fusion implosions part 2: systematic flow anomalies and impact of low modes on performances in OMEGA experiments

Colaïtis¹,

Igumenshchev²,

Turnbull³

et al. 2022

Plasma Phys. Control. Fusion

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We present the ﬁrst 3-D radiation-hydrodynamic simulations of directly driven inertial conﬁnement fusion implosions with an inline package for polarized crossed-beam energy transfer, which were used to assess the impact of the current Distributed Polarization Rotators (DPRs) on OMEGA as well as other known sources of asymmetry. Applied to OMEGA implosions, the simulations predict bang times with no need for ad hoc multipliers, as well as yields—if you separately account for the impacts of imprint and fuel age. Magnitude of the ﬂow is well reproduced when the low mode sources are large, whereas the modeling of stalk is thought to be required to match the ﬂow magnitude in the remaining cases. For the cases explored in more details, polarized CBET—the only known systematic drive asymmetry, brought the results closest to the measured ﬂow vectors. The remaining discrepencies are shown to be stemming from the limited knowledge of the laser pointing modes. For typical current levels of beam mispointing, power imbalance, target oﬀset, and asymmetry caused by polarized CBET, low modes degrade the yield by more than 40%. The current strategy of attempting to compensate the mode-1 asymmetry with a preimposed target oﬀset recovers only about 1/3 of the losses caused by the low modes due to the dynamic nature of the multiple asymmetries and the presence of low modes other than l = 1. Therefore, addressing the root causes of the drive asymmetries is apt to be more beneﬁcial. To that end, one possible solution to the speciﬁc issue of polarized CBET (10µm DPRs) is shown to work well.

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Section: Systematic Anomalies In Current Best-setup Omega Implosionssupporting

confidence: 85%

3D simulations of inertial confinement fusion implosions part 2: systematic flow anomalies and impact of low modes on performances in OMEGA experiments

Colaïtis¹,

Igumenshchev²,

Turnbull³

et al. 2022

Plasma Phys. Control. Fusion

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Analysis of core asymmetries in inertial confinement fusion implosions using three-dimensional hot-spot reconstruction

et al. 2022

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Three-dimensional effects play a crucial role during the hot-spot formation in inertial confinement fusion (ICF) implosions. A data analysis technique for 3D hot-spot reconstruction from experimental observables has been developed to characterize the effects of low modes on 3D hot-spot formations. In nuclear measurements, the effective flow direction, governed by the maximum eigenvalue in the velocity variance of apparent ion temperatures, has been found to agree with the measured hot-spot flows for implosions dominated by mode [Formula: see text]. Asymmetries in areal-density ( ρR) measurements were found to be characterized by a unique cosine variation along the hot-spot flow axis. In x-ray images, a 3D hot-spot x-ray emission tomography method was developed to reconstruct the 3D hot-spot plasma emissivity using a generalized spherical-harmonic Gaussian function. The gradient-descent algorithm was used to optimize the mapping between the projections from the 3D hot-spot emission model and the measured x-ray images along multiple views. This work establishes a platform to analyze 3D low-mode core asymmetries in ICF.

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Neutron time of flight (nToF) detectors for inertial fusion experiments

Moore

Schlossberg

Appelbe

et al. 2023

Review of Scientific Instruments

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Neutrons generated in Inertial Confinement Fusion (ICF) experiments provide valuable information to interpret the conditions reached in the plasma. The neutron time-of-flight (nToF) technique is well suited for measuring the neutron energy spectrum due to the short time (100 ps) over which neutrons are typically emitted in ICF experiments. By locating detectors 10s of meters from the source, the neutron energy spectrum can be measured to high precision. We present a contextual review of the current state of the art in nToF detectors at ICF facilities in the United States, outlining the physics that can be measured, the detector technologies currently deployed and analysis techniques used.

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Application of an energy-dependent instrument response function to analysis of nTOF data from cryogenic DT experiments

Cited by 4 publications

References 16 publications

3D simulations of inertial confinement fusion implosions part 2: systematic flow anomalies and impact of low modes on performances in OMEGA experiments

3D simulations of inertial confinement fusion implosions part 2: systematic flow anomalies and impact of low modes on performances in OMEGA experiments

Analysis of core asymmetries in inertial confinement fusion implosions using three-dimensional hot-spot reconstruction

Neutron time of flight (nToF) detectors for inertial fusion experiments

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