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Title: Hydrodynamic model for expansion and collisional relaxation of x-ray laser-excited multi-component nanoplasma

The irradiation of an atomic cluster with a femtosecond x-ray free-electron laser pulse results in a nanoplasma formation. This typically occurs within a few hundred femtoseconds. By this time the x-ray pulse is over, and the direct photoinduced processes no longer contributing. All created electrons within the nanoplasma are thermalized. The nanoplasma thus formed is a mixture of atoms, electrons, and ions of various charges. While expanding, it is undergoing electron impact ionization and three-body recombination. Below we present a hydrodynamic model to describe the dynamics of such multi-component nanoplasmas. The model equations are derived by taking the moments of the corresponding Boltzmann kinetic equations. We include the equations obtained, together with the source terms due to electron impact ionization and three-body recombination, in our hydrodynamic solver. Model predictions for a test case, expanding spherical Ar nanoplasma, are obtained. With this model, we complete the two-step approach to simulate x-ray created nanoplasmas, enabling computationally efficient simulations of their picosecond dynamics. Moreover, the hydrodynamic framework including collisional processes can be easily extended for other source terms and then applied to follow relaxation of any finite non-isothermal multi-component nanoplasma with its components relaxed into local thermodynamic equilibrium.
Authors:
 [1] ;  [2] ;  [1] ;  [2] ;  [3]
  1. Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg (Germany)
  2. (Germany)
  3. (Poland)
Publication Date:
OSTI Identifier:
22493831
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 1; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ARGON; ATOMIC CLUSTERS; ATOMS; BOLTZMANN EQUATION; ELECTRONS; FREE ELECTRON LASERS; HYDRODYNAMIC MODEL; IONIZATION; IONS; LASER RADIATION; LTE; NANOSTRUCTURES; PLASMA; RECOMBINATION; RELAXATION; SOURCE TERMS; SPHERICAL CONFIGURATION; THREE-BODY PROBLEM; X RADIATION; X-RAY LASERS