Prospects for the diagnosis of electron-ion temperature equilibration rates of warm dense matter by ultra-short pulse hard X-ray diffraction with an X-ray free electron laser

Ultra-short pulse kiloelectronvolt X-ray diffraction with an X-ray free electron laser and its potential for the diagnosis of electron-ion equilibration rates of warm dense matter are evaluated. A simple experimental configuration is suggested for the generation and subsequent probing of warm dense aluminium with the TESLA X-ray free electron laser. Differential scattering cross-sections are computed in an approximate manner with Thomas-Fermi form factors and tabular ion-ion static structure factors of one-component plasmas, inclusive of electron screening and degeneracy. This requires simulation of the sample, for which we use a hydrodynamic code featuring the Sesame equation of state, Thomas-Fermi ionisation and cold solid opacities (for the calculation of energy deposition). The effect of electron-ion equilibration rate on the evolution of the diffraction pattern on a picosecond time-scale is investigated. Finally, the signal level expected from experiment is estimated, indicating that measurements with good angular-resolution are possible. (C) 2006 Elsevier B.V. All rights reserved.