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This content will become publicly available on February 1, 2019

Title: Clocking Femtosecond Collisional Dynamics via Resonant X-Ray Spectroscopy

Electron-ion collisional dynamics is of fundamental importance in determining plasma transport properties, nonequilibrium plasma evolution, and electron damage in diffraction imaging applications using bright x-ray free-electron lasers (FELs). Here in this paper, we describe the first experimental measurements of ultrafast electron impact collisional ionization dynamics using resonant core-hole spectroscopy in a solid-density magnesium plasma, created and diagnosed with the Linac Coherent Light Source x-ray FEL. By resonantly pumping the 1s → 2p transition in highly charged ions within an optically thin plasma, we have measured how off-resonance charge states are populated via collisional processes on femtosecond time scales. We present a collisional cross section model that matches our results and demonstrates how the cross sections are enhanced by dense-plasma effects including continuum lowering. Nonlocal thermodynamic equilibrium collisional radiative simulations show excellent agreement with the experimental results and provide new insight on collisional ionization and three-body-recombination processes in the dense-plasma regime.
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [1] ;  [6] ;  [7] ;  [1] ;  [3] ;  [6] ;  [8] ;  [6] ;  [1] ;  [2] ;  [4] ;  [9] ;  [1] ;  [2] ;  [1]
  1. Univ. of Oxford (United Kingdom). Clarendon Lab., Dept. of Physics
  2. Univ. Politecnica de Madrid, Madrid (Spain). Inst. de Fusion Nuclear
  3. Academy of Sciences of the Czech Republic (ASCR), Prague (Czech Republic). Inst. of Physics; Inst. of Plasma Physics CAS, Prague (Czech Republic)
  4. Academy of Sciences of the Czech Republic (ASCR), Prague (Czech Republic). Inst. of Physics
  5. Intl Atomic Energy Agency (IAEA), Vienna (Austria). Atomic and Molecular Data Unit, Nuclear Data Section
  6. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  7. Academy of Sciences of the Czech Republic (ASCR), Prague (Czech Republic)
  8. Univ. of California, Berkeley, CA (United States). Dept. of Physics
  9. European X-ray Free-Electron Laser (XFEL), Hamburg (Germany)
Publication Date:
Grant/Contract Number:
AC02-76SF00515; EP/P015794/1; EP/L000849/1; 665207; 17-05167S; 17-05076S; LG15013; Z.02.1.01/0.0/0.0/16_013/0001552
Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 120; Journal Issue: 5; Journal ID: ISSN 0031-9007
American Physical Society (APS)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
OSTI Identifier: