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Title: Spatially resolved X-ray emission measurements of the residual velocity during the stagnation phase of inertial confinement fusion implosion experiments

Abstract

A technique for measuring residual motion during the stagnation phase of an indirectly driven inertial confinement experiment has been implemented. Our method infers a velocity from spatially and temporally resolved images of the X-ray emission from two orthogonal lines of sight. This work investigates the accuracy of recovering spatially resolved velocities from the X-ray emission data. A detailed analytical and numerical modeling of the X-ray emission measurement shows that the accuracy of this method increases as the displacement that results from a residual velocity increase. For the typical experimental configuration, signal-to-noise ratios, and duration of X-ray emission, it is estimated that the fractional error in the inferred velocity rises above 50% as the velocity of emission falls below 24 μm/ns. Furthermore, by inputting measured parameters into this model, error estimates of the residual velocity as inferred from the X-ray emission measurements are now able to be generated for experimental data. Details of this analysis are presented for an implosion experiment conducted with an unintentional radiation flux asymmetry. The analysis shows a bright localized region of emission that moves through the larger emitting volume at a relatively higher velocity towards the location of the imposed flux deficit. Our technique allows formore » the possibility of spatially resolving velocity flows within the so-called central hot spot of an implosion. This information would help to refine our interpretation of the thermal temperature inferred from the neutron time of flight detectors and the effect of localized hydrodynamic instabilities during the stagnation phase. Across several experiments, along a single line of sight, the average difference in magnitude and direction of the measured residual velocity as inferred from the X-ray and neutron time of flight detectors was found to be ~13 μm/ns and ~14°, respectively.« less

Authors:
ORCiD logo [1];  [1];  [1];  [1];  [1];  [1];  [1]; ORCiD logo [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [2];  [1];  [3];  [1] more »;  [4];  [1]; ORCiD logo [1];  [5];  [5];  [5]; ORCiD logo [5];  [5];  [5];  [5];  [5] « less
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. General Atomics, San Diego, CA (United States)
  3. Laboratory for Laser Energetics, Rochester, NY (United States)
  4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  5. Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550, USA
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1337001
Alternate Identifier(s):
OSTI ID: 1261222
Report Number(s):
LLNL-JRNL-690145
Journal ID: ISSN 1070-664X; PHPAEN
Grant/Contract Number:
AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 23; Journal Issue: 7; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION

Citation Formats

Ruby, J. J., Pak, A., Field, J. E., Ma, T., Spears, B. K., Benedetti, L. R., Bradley, D. K., Berzak Hopkins, L. F., Casey, D. T., Döppner, T., Eder, D., Fittinghoff, D., Grim, G., Hatarik, R., Hinkel, D. E., Izumi, N., Kilkenny, J. D., Khan, S. F., Knauer, J. P., Kritcher, A. L., Merrill, F. E., Moody, J. D., Nagel, S. R., Park, H. -S., Salmonson, J. D., Sayre, D. B., Callahan, D. A., Hsing, W. W., Hurricane, O. A., Patel, P. K., and Edwards, M. J.. Spatially resolved X-ray emission measurements of the residual velocity during the stagnation phase of inertial confinement fusion implosion experiments. United States: N. p., 2016. Web. doi:10.1063/1.4956468.
Ruby, J. J., Pak, A., Field, J. E., Ma, T., Spears, B. K., Benedetti, L. R., Bradley, D. K., Berzak Hopkins, L. F., Casey, D. T., Döppner, T., Eder, D., Fittinghoff, D., Grim, G., Hatarik, R., Hinkel, D. E., Izumi, N., Kilkenny, J. D., Khan, S. F., Knauer, J. P., Kritcher, A. L., Merrill, F. E., Moody, J. D., Nagel, S. R., Park, H. -S., Salmonson, J. D., Sayre, D. B., Callahan, D. A., Hsing, W. W., Hurricane, O. A., Patel, P. K., & Edwards, M. J.. Spatially resolved X-ray emission measurements of the residual velocity during the stagnation phase of inertial confinement fusion implosion experiments. United States. doi:10.1063/1.4956468.
Ruby, J. J., Pak, A., Field, J. E., Ma, T., Spears, B. K., Benedetti, L. R., Bradley, D. K., Berzak Hopkins, L. F., Casey, D. T., Döppner, T., Eder, D., Fittinghoff, D., Grim, G., Hatarik, R., Hinkel, D. E., Izumi, N., Kilkenny, J. D., Khan, S. F., Knauer, J. P., Kritcher, A. L., Merrill, F. E., Moody, J. D., Nagel, S. R., Park, H. -S., Salmonson, J. D., Sayre, D. B., Callahan, D. A., Hsing, W. W., Hurricane, O. A., Patel, P. K., and Edwards, M. J.. Fri . "Spatially resolved X-ray emission measurements of the residual velocity during the stagnation phase of inertial confinement fusion implosion experiments". United States. doi:10.1063/1.4956468. https://www.osti.gov/servlets/purl/1337001.
@article{osti_1337001,
title = {Spatially resolved X-ray emission measurements of the residual velocity during the stagnation phase of inertial confinement fusion implosion experiments},
author = {Ruby, J. J. and Pak, A. and Field, J. E. and Ma, T. and Spears, B. K. and Benedetti, L. R. and Bradley, D. K. and Berzak Hopkins, L. F. and Casey, D. T. and Döppner, T. and Eder, D. and Fittinghoff, D. and Grim, G. and Hatarik, R. and Hinkel, D. E. and Izumi, N. and Kilkenny, J. D. and Khan, S. F. and Knauer, J. P. and Kritcher, A. L. and Merrill, F. E. and Moody, J. D. and Nagel, S. R. and Park, H. -S. and Salmonson, J. D. and Sayre, D. B. and Callahan, D. A. and Hsing, W. W. and Hurricane, O. A. and Patel, P. K. and Edwards, M. J.},
abstractNote = {A technique for measuring residual motion during the stagnation phase of an indirectly driven inertial confinement experiment has been implemented. Our method infers a velocity from spatially and temporally resolved images of the X-ray emission from two orthogonal lines of sight. This work investigates the accuracy of recovering spatially resolved velocities from the X-ray emission data. A detailed analytical and numerical modeling of the X-ray emission measurement shows that the accuracy of this method increases as the displacement that results from a residual velocity increase. For the typical experimental configuration, signal-to-noise ratios, and duration of X-ray emission, it is estimated that the fractional error in the inferred velocity rises above 50% as the velocity of emission falls below 24 μm/ns. Furthermore, by inputting measured parameters into this model, error estimates of the residual velocity as inferred from the X-ray emission measurements are now able to be generated for experimental data. Details of this analysis are presented for an implosion experiment conducted with an unintentional radiation flux asymmetry. The analysis shows a bright localized region of emission that moves through the larger emitting volume at a relatively higher velocity towards the location of the imposed flux deficit. Our technique allows for the possibility of spatially resolving velocity flows within the so-called central hot spot of an implosion. This information would help to refine our interpretation of the thermal temperature inferred from the neutron time of flight detectors and the effect of localized hydrodynamic instabilities during the stagnation phase. Across several experiments, along a single line of sight, the average difference in magnitude and direction of the measured residual velocity as inferred from the X-ray and neutron time of flight detectors was found to be ~13 μm/ns and ~14°, respectively.},
doi = {10.1063/1.4956468},
journal = {Physics of Plasmas},
number = 7,
volume = 23,
place = {United States},
year = {Fri Jul 01 00:00:00 EDT 2016},
month = {Fri Jul 01 00:00:00 EDT 2016}
}

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  • A technique for measuring residual motion during the stagnation phase of an indirectly driven inertial confinement experiment has been implemented. This method infers a velocity from spatially and temporally resolved images of the X-ray emission from two orthogonal lines of sight. This work investigates the accuracy of recovering spatially resolved velocities from the X-ray emission data. A detailed analytical and numerical modeling of the X-ray emission measurement shows that the accuracy of this method increases as the displacement that results from a residual velocity increase. For the typical experimental configuration, signal-to-noise ratios, and duration of X-ray emission, it is estimatedmore » that the fractional error in the inferred velocity rises above 50% as the velocity of emission falls below 24 μm/ns. By inputting measured parameters into this model, error estimates of the residual velocity as inferred from the X-ray emission measurements are now able to be generated for experimental data. Details of this analysis are presented for an implosion experiment conducted with an unintentional radiation flux asymmetry. The analysis shows a bright localized region of emission that moves through the larger emitting volume at a relatively higher velocity towards the location of the imposed flux deficit. This technique allows for the possibility of spatially resolving velocity flows within the so-called central hot spot of an implosion. This information would help to refine our interpretation of the thermal temperature inferred from the neutron time of flight detectors and the effect of localized hydrodynamic instabilities during the stagnation phase. Across several experiments, along a single line of sight, the average difference in magnitude and direction of the measured residual velocity as inferred from the X-ray and neutron time of flight detectors was found to be ∼13 μm/ns and ∼14°, respectively.« less
  • A compact and simple multiframe x-ray imaging system was developed in order to monitor the implosion of spherical targets in inertial confinement fusion research. Time intervals between consecutive frames can be adjusted flexibly, and the maximum number of adjacent frames is 20 for an overall duration of 1.4 ns. Each frame is recorded with a temporal resolution of 83{plus minus}20 ps, a spatial resolution of 10 lp/mm at a modulation transfer function of 20%, and an intensity dynamic range of 10{sup 3}. A proximity focused image intensifier with two microchannel plates allows to obtain a gain of 10{sup 5}. Measuredmore » temporal response and gain characteristics could be reproduced by a simple Monte Carlo calculation.« less
  • We discuss the processing of data recorded with multimonochromatic x-ray imagers (MMI) in inertial confinement fusion experiments. The MMI records hundreds of gated, spectrally resolved images that can be used to unravel the spatial structure of the implosion core. In particular, we present a new method to determine the centers in all the array of images, a better reconstruction technique of narrowband implosion core images, two algorithms to determine the shape and size of the implosion core volume based on reconstructed broadband images recorded along three-quasiorthogonal lines of sight, and the removal of artifacts from the space-integrated spectra.
  • When used for the production of an x-ray imaging backlighter source on Sandia National Laboratories' 20 MA, 100 ns rise-time Z accelerator [M. K. Matzen et al., Phys. Plasmas 12, 055503 (2005)], the terawatt-class, multikilojoule, 526.57 nm Z-Beamlet laser (ZBL) [P. K. Rambo et al., Appl. Opt. 44, 2421 (2005)], in conjunction with the 6.151 keV, Mn-He{sub {alpha}} curved-crystal imager [D. B. Sinars et al., Rev. Sci. Instrum. 75, 3672 (2004)], is capable of providing a high quality x radiograph per Z shot for various high-energy-density physics experiments. Enhancements to this imaging system during 2005 have led to the capturemore » of inertial confinement fusion capsule implosion and complex hydrodynamics images of significantly higher quality. The three main improvements, all leading effectively to enhanced image plane brightness, were bringing the source inside the Rowland circle to approximately double the collection solid angle, replacing direct exposure film with Fuji BAS-TR2025 image plate (read with a Fuji BAS-5000 scanner), and generating a 0.3-0.6 ns, {approx}200 J prepulse 2 ns before the 1.0 ns, {approx}1 kJ main pulse to more than double the 6.151 keV flux produced compared with a single 1 kJ pulse. It appears that the 20{+-}5 {mu}m imaging resolution is limited by the 25 {mu}m scanning resolution of the BAS-5000 unit, and to this end, a higher resolution scanner will replace it. ZBL is presently undergoing modifications to provide two temporally separated images ('two-frame') per Z shot for this system before the accelerator closes down in summer 2006 for the Z-refurbished (ZR) upgrade. In 2008, after ZR, it is anticipated that the high-energy petawatt (HEPW) addition to ZBL will be completed, possibly allowing high-energy 11.2224 and 15.7751 keV K{alpha}{sub 1} curved-crystal imaging to be performed. With an ongoing several-year project to develop a highly sensitive multiframe ultrafast digital x-ray camera (MUDXC), it is expected that two-frame HEPW 11 and 16 keV imaging and four-frame ZBL 6.151 keV curved-crystal imaging will be possible. MUDXC will be based on the technology of highly cooled silicon and germanium photodiode arrays and ultrafast, radiation-hardened integrated circuitry.« less