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Title: Conceptual design of initial opacity experiments on the national ignition facility

Abstract

Accurate models of X-ray absorption and re-emission in partly stripped ions are necessary to calculate the structure of stars, the performance of hohlraums for inertial confinement fusion and many other systems in high-energy-density plasma physics. Despite theoretical progress, a persistent discrepancy exists with recent experiments at the Sandia Z facility studying iron in conditions characteristic of the solar radiative–convective transition region. The increased iron opacity measured at Z could help resolve a longstanding issue with the standard solar model, but requires a radical departure for opacity theory. To replicate the Z measurements, an opacity experiment has been designed for the National Facility (NIF). The design uses established techniques scaled to NIF. A laser-heated hohlraum will produce X-ray-heated uniform iron plasmas in local thermodynamic equilibrium (LTE) at temperatures$${\geqslant}150$$ eV and electron densities$${\geqslant}7\times 10^{21}~\text{cm}^{-3}$$. The iron will be probed using continuum X-rays emitted in a$${\sim}200$$ ps,$${\sim}200~\unicode[STIX]{x03BC}\text{m}$$diameter source from a 2 mm diameter polystyrene (CH) capsule implosion. In this design,$2/3$$of the NIF beams deliver 500 kJ to the$${\sim}6$$ mm diameter hohlraum, and the remaining$$1/3$directly drive the CH capsule with 200 kJ. Calculations indicate this capsule backlighter should outshine the iron sample, delivering a point-projection transmission opacity measurement to a time-integrated X-ray spectrometer viewing down the hohlraum axis. Preliminary experiments to develop the backlighter and hohlraum are underway, informing simulated measurements to guide the final design.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1358319
Report Number(s):
LLNL-JRNL-700383
Journal ID: ISSN 0022-3778; applab
DOE Contract Number:  
AC52-07NA27344
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Plasma Physics; Journal Volume: 83; Journal Issue: 01
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 79 ASTRONOMY AND ASTROPHYSICS; 70 PLASMA PHYSICS AND FUSION

Citation Formats

Heeter, R.  F., Bailey, J.  E., Craxton, R.  S., DeVolder, B.  G., Dodd, E.  S., Garcia, E.  M., Huffman, E.  J., Iglesias, C.  A., King, J.  A., Kline, J.  L., Liedahl, D.  A., McKenty, P.  W., Opachich, Y.  P., Rochau, G.  A., Ross, P.  W., Schneider, M.  B., Sherrill, M.  E., Wilson, B.  G., Zhang, R., and Perry, T.  S. Conceptual design of initial opacity experiments on the national ignition facility. United States: N. p., 2017. Web. doi:10.1017/S0022377816001173.
Heeter, R.  F., Bailey, J.  E., Craxton, R.  S., DeVolder, B.  G., Dodd, E.  S., Garcia, E.  M., Huffman, E.  J., Iglesias, C.  A., King, J.  A., Kline, J.  L., Liedahl, D.  A., McKenty, P.  W., Opachich, Y.  P., Rochau, G.  A., Ross, P.  W., Schneider, M.  B., Sherrill, M.  E., Wilson, B.  G., Zhang, R., & Perry, T.  S. Conceptual design of initial opacity experiments on the national ignition facility. United States. doi:10.1017/S0022377816001173.
Heeter, R.  F., Bailey, J.  E., Craxton, R.  S., DeVolder, B.  G., Dodd, E.  S., Garcia, E.  M., Huffman, E.  J., Iglesias, C.  A., King, J.  A., Kline, J.  L., Liedahl, D.  A., McKenty, P.  W., Opachich, Y.  P., Rochau, G.  A., Ross, P.  W., Schneider, M.  B., Sherrill, M.  E., Wilson, B.  G., Zhang, R., and Perry, T.  S. Mon . "Conceptual design of initial opacity experiments on the national ignition facility". United States. doi:10.1017/S0022377816001173. https://www.osti.gov/servlets/purl/1358319.
@article{osti_1358319,
title = {Conceptual design of initial opacity experiments on the national ignition facility},
author = {Heeter, R.  F. and Bailey, J.  E. and Craxton, R.  S. and DeVolder, B.  G. and Dodd, E.  S. and Garcia, E.  M. and Huffman, E.  J. and Iglesias, C.  A. and King, J.  A. and Kline, J.  L. and Liedahl, D.  A. and McKenty, P.  W. and Opachich, Y.  P. and Rochau, G.  A. and Ross, P.  W. and Schneider, M.  B. and Sherrill, M.  E. and Wilson, B.  G. and Zhang, R. and Perry, T.  S.},
abstractNote = {Accurate models of X-ray absorption and re-emission in partly stripped ions are necessary to calculate the structure of stars, the performance of hohlraums for inertial confinement fusion and many other systems in high-energy-density plasma physics. Despite theoretical progress, a persistent discrepancy exists with recent experiments at the Sandia Z facility studying iron in conditions characteristic of the solar radiative–convective transition region. The increased iron opacity measured at Z could help resolve a longstanding issue with the standard solar model, but requires a radical departure for opacity theory. To replicate the Z measurements, an opacity experiment has been designed for the National Facility (NIF). The design uses established techniques scaled to NIF. A laser-heated hohlraum will produce X-ray-heated uniform iron plasmas in local thermodynamic equilibrium (LTE) at temperatures${\geqslant}150$ eV and electron densities${\geqslant}7\times 10^{21}~\text{cm}^{-3}$. The iron will be probed using continuum X-rays emitted in a${\sim}200$ ps,${\sim}200~\unicode[STIX]{x03BC}\text{m}$diameter source from a 2 mm diameter polystyrene (CH) capsule implosion. In this design,$2/3$of the NIF beams deliver 500 kJ to the${\sim}6$ mm diameter hohlraum, and the remaining$1/3$directly drive the CH capsule with 200 kJ. Calculations indicate this capsule backlighter should outshine the iron sample, delivering a point-projection transmission opacity measurement to a time-integrated X-ray spectrometer viewing down the hohlraum axis. Preliminary experiments to develop the backlighter and hohlraum are underway, informing simulated measurements to guide the final design.},
doi = {10.1017/S0022377816001173},
journal = {Journal of Plasma Physics},
number = 01,
volume = 83,
place = {United States},
year = {Mon Jan 09 00:00:00 EST 2017},
month = {Mon Jan 09 00:00:00 EST 2017}
}