Ex situ calibration of the scattered-light time-history diagnostic on the National Ignition Facility

S Kostick; T Filkins; M J Rosenberg; J Katz; W Theobald; N Lemos; E Tubman; R Sommers; J E Hernandez; G Swadling; J S Ross; P B Radha; F Grullon; J M Heinmiller; J Fornes; P Hillyard; J McCumber; L Ceurvorst; S P Regan

doi:10.1063/5.0218987

Ex situ calibration of the scattered-light time-history diagnostic on the National Ignition Facility

Rev Sci Instrum. 2024 Sep 1;95(9):093524. doi: 10.1063/5.0218987.

Authors

S Kostick¹, T Filkins¹, M J Rosenberg¹, J Katz¹, W Theobald^{1

2

3}, N Lemos⁴, E Tubman⁴, R Sommers⁴, J E Hernandez⁴, G Swadling⁴, J S Ross⁴, P B Radha¹, F Grullon⁴, J M Heinmiller⁵, J Fornes⁵, P Hillyard⁵, J McCumber⁵, L Ceurvorst¹, S P Regan¹

Affiliations

¹ Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA.
² Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627-0132, USA.
³ Focused Energy GmbH, Im Tiefen See 45, 64293 Darmstadt, Germany.
⁴ Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
⁵ Nevada National Security Site, Livermore, California 94551, USA.

PMID: 39283179
DOI: 10.1063/5.0218987

Abstract

The scattered-light time-history diagnostic (SLTD) suite measures time-resolved scattered light in three wavelength bands: stimulated Brillouin scattering (350-352 nm), stimulated Raman scattering (430-760 nm), and plasma emission at half the laser frequency (695-735 nm), at 15 locations around the National Ignition Facility (NIF) target chamber. The SLTD, along with the full-aperture backscatter station (FABS), collects scattered light from direct- and indirect-drive inertial confinement fusion experiments. The SLTD calibration was revisited after a discrepancy between FABS and SLTD measurements was observed on NIF polar direct-drive [Skupsky et al., Phys. Plasmas 11, 2763 (2004)] experiments. An integrated calibration of the SLTD was performed for the first time, and individual components were also calibrated for the wavelengths of 351, 527, and 532 nm. The optical transmission of the instrument was measured to be (1.12 ± 0.04) × 10-7 and (1.96 ± 0.11) × 10-7 for the wavelengths of 351 and 532 nm, respectively. The revised calibration at 351 nm brings the SLTD measured scattered energy in agreement with the FABS measured scattered energy after additionally accounting for the degradation of an optical element in FABS. This decreased the inferred absorption by 7% for a representative experiment. However, discrepancies remain between FABS and SLTD measurements in the SRS band (532 nm).