Measurements of unequilibrated ions in hot, solid-density plasmas via x-ray lineshapes

ORAL

Abstract

Ion-electron equilibration drives plasma dynamics but is challenging to model at high densities. We present simultaneous measurements of electron and ion temperatures in solid-density, highly ionized Ti based on high-resolution x-ray Stark lineshapes; analysis implies that ions are significantly cooler than electrons. Foils with buried Ti layers are heated with a high-intensity laser with extreme temporal contrast. The localized Ti regions emit x-ray lineshapes that are both double-peaked and redshifted; these features, both hallmarks of Stark broadening, are differently affected by electron density and ion temperature. The data is interpreted with a new lineshape code that abandons the common assumption of dipole interactions for the electron broadening; comparing the data with this model strongly constrains both the ion temperature and the electron density. The electron temperature is independently constrained by x-ray line ratios. Measured plasmas are near solid density and support a significant temperature differential between hot electrons and cooler ions. The lack of equilibration suggests that either (1) the equilibration rate is substantially slower than the Spitzer equation predicts or (2) ion heat transport plays an important role in the system.

*This work was supported by the DOE Office of Science, Fusion Energy Sciences under Contract No. DE-SC0021246: the LaserNetUS initiative at Colorado State University's Advanced Beam Laboratory, and was performed under the auspices of the U.S. DOE by Princeton Plasma Physics Laboratory under contract DE-AC02-09CH11466, Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344, and Sandia National Laboratories under contract DE-NA0003525.

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Publication: "Solid-density ion temperature from redshifted and double-peaked Stark lineshapes," submitted to PRL.

Presenters

  • Brian F Kraus

    • Princeton Plasma Physics Laboratory
    • PPPL
    • Princeton Plasma Physics Laboratory (PPPL), USA

Authors

  • Brian F Kraus

    • Princeton Plasma Physics Laboratory
    • PPPL
    • Princeton Plasma Physics Laboratory (PPPL), USA

  • Lan Gao

    • Princeton Plasma Physics Laboratory
    • PPPL
    • Princeton University

  • Kenneth W Hill

    • Princeton University
    • Princeton Plasma Physics Laboratory

  • Manfred L Bitter

    • Princeton Plasma Physics Laboratory

  • P.C. C Efthimion

    • Princeton Plasma Physics Laboratory
    • PPPL

  • Thomas A Gomez

    • Sandia National Laboratories

  • Adam F Moreau

    • Colorado State University

  • Reed C Hollinger

    • Colorado State University
    • Electrical and Computer Engineering Department, Colorado State University, Fort Collins, CO 80521 USA

  • Shoujun Wang

    • Colorado State University
    • Electrical and Computer Engineering Department, Colorado State University, Fort Collins, CO 80521 USA

  • Huanyu Song

    • Colorado State University
    • Electrical and Computer Engineering Department, Colorado State University, Fort Collins, CO 80521 USA

  • Jorge J Rocca

    • Colorado State University
    • Electrical and Computer Engineering Department, Colorado State University, Fort Collins, CO 80521 USA

  • Roberto C Mancini

    • University of Nevada, Reno