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SUMMARY:SPC Seminar – Plasma – Audrey DeVault (MIT)
DESCRIPTION:Speaker: Audrey DeVault (MIT)\nTitle: Approaches to Developing 
 Time-Resolving Neutron Diagnostics at the NIF\nAbstract: The development o
 f a time-resolving neutron diagnostic underway for the purpose of analyzin
 g inertial confinement fusion (ICF) implosions at the National Ignition Fa
 cility (NIF).  Time-resolved neutron spectra can be analyzed to infer Ti(
 t)\, ρR(t)\, and Yn(t)\, which provide valuable information about the dyn
 amics of an ICF implosion. In particular\, they would help identify factor
 s limiting burn propagation in order to improve gain from the igniting imp
 losions now repeatedly achieved at the NIF. Two approaches to obtaining ti
 me-resolved neutron spectra are presented: the time-resolving Magnetic Rec
 oil Spectrometer (MRSt) and the tomographic neutron Time of Flight (nTOF) 
 scheme.  The MRSt utilizes a front end similar to the current magnetic re
 coil spectrometer fielded on NIF\, with a CD foil converting neutrons to d
 euterons and a magnet system which momentum-separates the deuterons. Howev
 er\, the backend is yet to be finalized. A novel\, simplified backend conc
 ept is currently being investigated\, utilizing a printed circuit board (P
 CB) to passively de-skew the incoming signal in time. The PCB takes advant
 age of propagation delay to slow down the signal from higher-energy deuter
 ons before recombining with that of simultaneously produced lower-energy d
 euterons\, producing energy spectra for discrete timesteps throughout the 
 implosion. Design and prototyping of a PCB backend is underway\, and cruci
 al design features are identified. The tomographic nTOF scheme employs mul
 tiple nTOF detectors at varied distances from Target Chamber Center (TCC).
  Close-in nTOFs capture more time-of-emission information\, while far-out 
 nTOFs capture more energy information\, allowing for multiple samplings of
  the neutron source spectra in energy and time-of-emission space\, enablin
 g tomographic reconstruction of the source spectra. Synthetic data studies
  are underway to probe the feasibility of this approach. Models of neutron
  source spectra in energy and time-of-emission are used to generate synthe
 tic datasets of collinear nTOFs\, with tunable distance\, noise\, time bin
 ning\, and instrument response function. An adaptive-rate Monte Carlo retr
 ieval code is then used to tomographically reconstruct the neutron source 
 function. Effective reconstruction of the neutron source function in energ
 y and time-of-emission is shown to be feasible with multiple collinear nTO
 FS\, and constraints on detector precision and placement are put forth.\nT
 his work is supported by Lawrence Livermore National Laboratory under Cont
 ract B652285. A. DeVault is supported by NNSA LRGF under Grant No. DE-NA00
 03960
URL:https://www.imperial.ac.uk/events/208691/spc-seminar-plasma-audrey-deva
 ult-mit/
DTSTART;TZID=Europe/London:20260422T150000
DTEND;TZID=Europe/London:20260422T160000
LOCATION:741\, Blackett Building\, South Kensington Campus\, Imperial Colle
 ge London\, London\, SW7 2AZ\, United Kingdom
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