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Title: Improving a high-efficiency, gated spectrometer for x-ray Thomson scattering experiments at the National Ignition Facility

Abstract

We are developing x-ray Thomson scattering for applications in implosion experiments at the National Ignition Facility. In particular we have designed and fielded MACS, a high-efficiency, gated x-ray spectrometer at 7.5-10 keV [T. Döppner et al., Rev. Sci. Instrum. 85, 11D617 (2014)]. Here in this paper we report on two new Bragg crystals based on Highly Oriented Pyrolytic Graphite (HOPG), a flat crystal and a dual-section cylindrically curved crystal. We have performed in situ calibration measurements using a brass foil target, and we used the flat HOPG crystal to measure Mo K-shell emission at 18 keV in 2nd order diffraction. Such high photon energy line emission will be required to penetrate and probe ultra-high-density plasmas or plasmas of mid-Z elements.

Authors:
 [1];  [2];  [3];  [1];  [1];  [4];  [5];  [1];  [1];  [1]; ORCiD logo [1];  [1];  [2];  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Univ. of California, Berkeley, CA (United States)
  3. Gesellschaft fur Schwerionenphysik, Darmstadt (Germany)
  4. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  5. SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
1360157
Grant/Contract Number:
AC02-76SF00515; AC52-07NA27344; 13-ERD-073
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 87; Journal Issue: 11; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; X-ray spectrometers; X-ray detectors; Calibration; Molybdenum; Copper

Citation Formats

Döppner, T., Kraus, D., Neumayer, P., Bachmann, B., Emig, J., Falcone, R. W., Fletcher, L. B., Hardy, M., Kalantar, D. H., Kritcher, A. L., Landen, O. L., Ma, T., Saunders, A. M., and Wood, R. D.. Improving a high-efficiency, gated spectrometer for x-ray Thomson scattering experiments at the National Ignition Facility. United States: N. p., 2016. Web. doi:10.1063/1.4959874.
Döppner, T., Kraus, D., Neumayer, P., Bachmann, B., Emig, J., Falcone, R. W., Fletcher, L. B., Hardy, M., Kalantar, D. H., Kritcher, A. L., Landen, O. L., Ma, T., Saunders, A. M., & Wood, R. D.. Improving a high-efficiency, gated spectrometer for x-ray Thomson scattering experiments at the National Ignition Facility. United States. doi:10.1063/1.4959874.
Döppner, T., Kraus, D., Neumayer, P., Bachmann, B., Emig, J., Falcone, R. W., Fletcher, L. B., Hardy, M., Kalantar, D. H., Kritcher, A. L., Landen, O. L., Ma, T., Saunders, A. M., and Wood, R. D.. Wed . "Improving a high-efficiency, gated spectrometer for x-ray Thomson scattering experiments at the National Ignition Facility". United States. doi:10.1063/1.4959874. https://www.osti.gov/servlets/purl/1360157.
@article{osti_1360157,
title = {Improving a high-efficiency, gated spectrometer for x-ray Thomson scattering experiments at the National Ignition Facility},
author = {Döppner, T. and Kraus, D. and Neumayer, P. and Bachmann, B. and Emig, J. and Falcone, R. W. and Fletcher, L. B. and Hardy, M. and Kalantar, D. H. and Kritcher, A. L. and Landen, O. L. and Ma, T. and Saunders, A. M. and Wood, R. D.},
abstractNote = {We are developing x-ray Thomson scattering for applications in implosion experiments at the National Ignition Facility. In particular we have designed and fielded MACS, a high-efficiency, gated x-ray spectrometer at 7.5-10 keV [T. Döppner et al., Rev. Sci. Instrum. 85, 11D617 (2014)]. Here in this paper we report on two new Bragg crystals based on Highly Oriented Pyrolytic Graphite (HOPG), a flat crystal and a dual-section cylindrically curved crystal. We have performed in situ calibration measurements using a brass foil target, and we used the flat HOPG crystal to measure Mo K-shell emission at 18 keV in 2nd order diffraction. Such high photon energy line emission will be required to penetrate and probe ultra-high-density plasmas or plasmas of mid-Z elements.},
doi = {10.1063/1.4959874},
journal = {Review of Scientific Instruments},
number = 11,
volume = 87,
place = {United States},
year = {Wed Aug 03 00:00:00 EDT 2016},
month = {Wed Aug 03 00:00:00 EDT 2016}
}

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  • We are developing x-ray Thomson scattering for applications in implosion experiments at the National Ignition Facility. In particular we have designed and fielded MACS, a high-efficiency, gated x-ray spectrometer at 7.5–10 keV [T. Döppner et al., Rev. Sci. Instrum. 85, 11D617 (2014)]. Here we report on two new Bragg crystals based on Highly Oriented Pyrolytic Graphite (HOPG), a flat crystal and a dual-section cylindrically curved crystal. We have performed in situ calibration measurements using a brass foil target, and we used the flat HOPG crystal to measure Mo K-shell emission at 18 keV in 2nd order diffraction. Such high photonmore » energy line emission will be required to penetrate and probe ultra-high-density plasmas or plasmas of mid-Z elements.« less
  • We have designed, built, and successfully fielded a highly efficient and gated Bragg crystal spectrometer for x-ray Thomson scattering measurements on the National Ignition Facility (NIF). It utilizes a cylindrically curved Highly Oriented Pyrolytic Graphite crystal. Its spectral range of 7.4–10 keV is optimized for scattering experiments using a Zn He-α x-ray probe at 9.0 keV or Mo K-shell line emission around 18 keV in second diffraction order. The spectrometer has been designed as a diagnostic instrument manipulator-based instrument for the NIF target chamber at the Lawrence Livermore National Laboratory, USA. Here, we report on details of the spectrometer snout, itsmore » novel debris shield configuration and an in situ spectral calibration experiment with a Brass foil target, which demonstrated a spectral resolution of E/ΔE = 220 at 9.8 keV.« less
  • We have developed a model for analysing x-ray Thomson scattering data from high-density, millimetre-scale inhomogeneous plasmas created during ultra-high pressure implosions at the National Ignition Facility in a spherically convergent geometry. The density weighting of the scattered signal and attenuation of the incident and scattered x-rays throughout the target are included using radial profiles of the density, opacity, ionization state, and temperature provided by radiation-hydrodynamics simulations. These simulations show that the scattered signal is strongly weighted toward the bulk of the shocked plasma and the Fermi degenerate material near the ablation front. We show that the scattered signal provides amore » good representation of the temperature of this highly nonuniform bulk plasma and can be determined to an accuracy of ca. 15% using typical data analysis techniques with simple 0D calculations. On the other hand, the mean ionization of the carbon in the bulk is underestimated. We suggest that this discrepancy is due to the convolution of scattering profiles from different regions of the target. Subsequently, we discuss modifications to the current platform to minimise the impact of inhomogeneities, as well as opacity, and also to enable probing of conditions more strongly weighted toward the compressed core.« less