XFEL resonant photo-pumping of dense plasmas and dynamic evolution of autoionizing core hole states

8th International Conference on Inertial Fusion Sciences and Applications

Rosmej, F.B.^1,2 ; Moinard, A.^1,2 ; Renner, O.^3 ; Galtier, E.^4,7 ; Lee, J.J.^4 ; Nagler, B.^4 ; Heimann, P.A.^4 ; Schlotter, W.^4 ; Turner, J.J.^4 ; Lee, R.W.^4 ; Makita, M.^5 ; Riley, D.^5 ; Seely, J.^6

Sorbonne Universités, Pierre and Marie Curie, UMR7605, LULI, Case 128, 4 place Jussieu, Paris Cedex 05

F-75252, France^1

LULI, Ecole Polytechnique, CEA, CNRS, Physique Atomique dans les Plasmas Denses, Palaiseau, France^2

Institute of Physics, Academy of Sciences CR, Prague, Czech Republic^3

SLAC Accelerator National Laboratory, CA, United States^4

Queen's University of Belfast, Centre for Plasma Physics, United Kingdom^5

Naval Research Laboratory, Washington

DC, United States^6

LULI-PAPD, United States^7

关键词: High energy density plasmas;    High energy density science;    Laser induced fluorescence;    Optical laser beams;    Proof-of-principle experiments;    Rotating cylinders;    Spherically bent crystals;    X-ray free electron lasers;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/688/1/012093/pdf
DOI  :  10.1088/1742-6596/688/1/012093

来源: IOP

【 摘 要 】

Similarly to the case of LIF (Laser-Induced Fluorescence), an equally revolutionary impact to science is expected from resonant X-ray photo-pumping. It will particularly contribute to a progress in high energy density science: pumped core hole states create X-ray transitions that can escape dense matter on a 10 fs-time scale without essential photoabsorption, thus providing a unique possibility to study matter under extreme conditions. In the first proof of principle experiment at the X-ray Free Electron Laser LCLS at SCLAC [Seely, J., Rosmej, F.B., Shepherd, R., Riley, D., Lee, R.W. Proposal to Perform the 1stHigh Energy Density Plasma Spectroscopic Pump/Probe Experiment", approved LCLS proposal L332 (2010)] we have successfully pumped inner-shell X-ray transitions in dense plasmas. The plasma was generated with a YAG laser irradiating solid Al and Mg targets attached to a rotating cylinder. In parallel to the optical laser beam, the XFEL was focused into the plasma plume at different delay times and pump energies. Pumped X-ray transitions have been observed with a spherically bent crystal spectrometer coupled to a Princeton CCD. By using this experimental configuration, we have simultaneously achieved extremely high spectral (λ/δλ ≈ 5000) and spatial resolution (δx≈70 μm) while maintaining high luminosity and a large spectral range covered (6.90 - 8.35 Å). By precisely measuring the variations in spectra emitted from plasma under action of XFEL radiation, we have successfully demonstrated transient X- ray pumping in a dense plasma.