Publications associated with Intense X-ray-Matter Interactions

Observation of ultrafast nonequilibrium collective dynamics in warm dense hydrogen.

Phys Rev Lett 104 (2010) 125002-

RR Fäustlin, T Bornath, T Döppner, S Düsterer, E Förster, C Fortmann, SH Glenzer, S Göde, G Gregori, R Irsig, T Laarmann, HJ Lee, B Li, K-H Meiwes-Broer, J Mithen, B Nagler, A Przystawik, H Redlin, R Redmer, H Reinholz, G Röpke, F Tavella, R Thiele, J Tiggesbäumker, S Toleikis, I Uschmann, SM Vinko, T Whitcher, U Zastrau, B Ziaja, T Tschentscher

We investigate ultrafast (fs) electron dynamics in a liquid hydrogen sample, isochorically and volumetrically heated to a moderately coupled plasma state. Thomson scattering measurements using 91.8 eV photons from the free-electron laser in Hamburg (FLASH at DESY) show that the hydrogen plasma has been driven to a nonthermal state with an electron temperature of 13 eV and an ion temperature below 0.1 eV, while the free-electron density is 2.8x10{20} cm{-3}. For dense plasmas, our experimental data strongly support a nonequilibrium kinetics model that uses impact ionization cross sections based on classical free-electron collisions.

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