Time-Resolved XUV Opacity Measurements of Warm Dense Aluminum
Journal article, 2020
The free-free opacity in plasmas is fundamental to our understanding of energy transport in stellar interiors and for inertial confinement fusion research. However, theoretical predictions in the challenging dense plasma regime are conflicting and there is a dearth of accurate experimental data to allow for direct model validation. Here we present time-resolved transmission measurements in solid-density Al heated by an XUV free-electron laser. We use a novel functional optimization approach to extract the temperature-dependent absorption coefficient directly from an oversampled pool of single-shot measurements, and find a pronounced enhancement of the opacity as the plasma is heated to temperatures of order of the Fermi energy. Plasma heating and opacity enhancement are observed on ultrafast timescales, within the duration of the femtosecond XUV pulse. We attribute further rises in the opacity on ps timescales to melt and the formation of warm dense matter.
Author
S. M. Vinko
University of Oxford
V. Vozda
Czech Academy of Sciences
Charles University
Jakob Andreasson
Czech Academy of Sciences
Chalmers, Physics, Materials Physics
S. Bajt
Deutsches Elektronen-Synchrotron (DESY)
J. Bielecki
European XFEL
T. Burian
Czech Academy of Sciences
J. Chalupsky
Czech Academy of Sciences
O. Ciricosta
University of Oxford
M. P. Desjarlais
Sandia National Laboratories
H. Fleckenstein
Deutsches Elektronen-Synchrotron (DESY)
J. Hajdu
Uppsala University
Czech Academy of Sciences
V Hajkova
Czech Academy of Sciences
P. Hollebon
University of Oxford
L. Juha
Czech Academy of Sciences
M. F. Kasim
University of Oxford
E. E. McBride
Stanford University
K. Muehlig
Uppsala University
T. R. Preston
European XFEL
D. S. Rackstraw
University of Oxford
S. Roling
University of Münster
S. Toleikis
Deutsches Elektronen-Synchrotron (DESY)
J. S. Wark
University of Oxford
H. Zacharias
University of Münster
Physical Review Letters
0031-9007 (ISSN) 1079-7114 (eISSN)
Vol. 124 22 225002Subject Categories
Atom and Molecular Physics and Optics
Fusion, Plasma and Space Physics
DOI
10.1103/PhysRevLett.124.225002
PubMed
32567902