Description
T. Tschentscher1, K. Appel1, E. Brambrink1, T. Cowan2, T. Feurer1, H. Sinn1, U. Zastrau1
1 European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
2 Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
X-ray radiation in the range of 5 - 20 keV provided by high brightness Free-Electron Laser (FEL) sources offer unprecedented new opportunities for studying phenomena and materials of high relevance to laser-driven fusion. Initial imaging experiments have shown the capability to study how matter is compressed by laser irradiation and how instabilities form and propagate [1,2]. In order to perform such studies more systematically in a dedicated experimental environment, an instrument for fusion research has been proposed for the European XFEL.
European XFEL is an international large-scale user facility for research using x-ray FEL radiation. This radiation is characterized by very intense, ultrashort and coherent pulses, complementary to both synchrotron and visible laser radiation. European XFEL currently offers x-ray FEL radiation in the range from 0.25 to 25 keV (0.05 – 5 nm) to seven science instruments, each dedicated to a specific area of application [3]. We now proposed a new instrument, coupled to a nanosecond laser with kJ pulse energy at the 3rd harmonic and pulse shaping capabilities, and a complementary femtosecond laser of PW-class pulse intensity. These lasers allow to excite and dynamically compress fusion relevant materials while the coherent, ultrashort and intense XFEL pulse will be used to diagnose the targets by a variety of different x-ray methods with O(200 nm) spatial and femtosecond temporal resolution.
Experiments will address the microphysics and dynamic behaviour of fusion targets during several, early states of compression: Non-uniformities arising from laser imprint, the development of laser-plasma instabilities, plasma formation and the onset of hydrodynamic instabilities, the launch of a shock wave into the target or ablator and, if present, shock propagation in the target, and finally hydrodynamic instability growth leading to mixing. As major x-ray techniques full-field imaging, small angle-scattering, and as well spectroscopic techniques will be available. Using these techniques the experiments will allow investigating the behaviour of different targets materials, e.g. foam or similar, under compression and laser excitation. The time- and spatially-resolved experimental data will provide important benchmarking of high-resolution rad-hydro simulations.
The instrument is expected to start operation before the end of this decade and an increase of the drive laser pulse energy, as well as a dedicated x-ray source, are planned for a second phase.
[1] G. Rigon et al., Nat. Commun. 12, 2679 (2021), doi: 10.1038/s41467-021-22891-w
[2] A. Laso-Garcia et al., Nat. Commun. 15, 7896 (2024), doi: 10.1038/s41467-024-52232-6
[3] T. Tschentscher et al., Appl. Sci. 7, 592 (2017), doi: 10.3390/app7060592