Measurements of fuel and ablator ρR in Symmetry-Capsule implosions with the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility

M Gatu Johnson; J A Frenje; C K Li; F H Séguin; R D Petrasso; R M Bionta; D T Casey; J A Caggiano; R Hatarik; H Y Khater; D B Sayre; J P Knauer; T C Sangster; H W Herrmann; J D Kilkenny

doi:10.1063/1.4886418

Measurements of fuel and ablator ρR in Symmetry-Capsule implosions with the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility

Rev Sci Instrum. 2014 Nov;85(11):11E104. doi: 10.1063/1.4886418.

Authors

M Gatu Johnson¹, J A Frenje¹, C K Li¹, F H Séguin¹, R D Petrasso¹, R M Bionta², D T Casey², J A Caggiano², R Hatarik², H Y Khater², D B Sayre², J P Knauer³, T C Sangster³, H W Herrmann⁴, J D Kilkenny⁵

Affiliations

¹ Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
² Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
³ Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA.
⁴ Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
⁵ General Atomics, San Diego, California 92186, USA.

PMID: 25430283
DOI: 10.1063/1.4886418

Abstract

The Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility (NIF) measures the neutron spectrum in the energy range of 4-20 MeV. This paper describes MRS measurements of DT-fuel and CH-ablator ρR in DT gas-filled symmetry-capsule implosions at the NIF. DT-fuel ρR's of 80-140 mg/cm(2) and CH-ablator ρR's of 400-680 mg/cm(2) are inferred from MRS data. The measurements were facilitated by an improved correction of neutron-induced background in the low-energy part of the MRS spectrum. This work demonstrates the accurate utilization of the complete MRS-measured neutron spectrum for diagnosing NIF DT implosions.