@article{7329,
  author = {J. Andreasson and B. Iwan and A. Andrejczuk and E. Abreu and M. Bergh and C. Caleman and A. J. Nelson and S. Bajt and J. Chalupsky and H. N. Chapman and R. R. Faustlin and V. Hajkova and P. A. Heimann and B. Hjorvarsson and L. Juha and D. Klinger and J. Krzywinski and B. Nagler and G. K. Palsson and W. Singer and M. M. Seibert and R. Sobicrajski and S. Tolcikis and T. Tschentscher and S. M. Vinko and R. W. Lee and J. Hajdu and N. Timneanu},
  title = {Saturated ablation in metal hydrides and acceleration of protons and deuterons to keV energies with a soft-x-ray laser},
  abstract = {Studies of materials under extreme conditions have relevance to a broad area of research, including planetary physics, fusion research, materials science, and structural biology with x-ray lasers. We study such extreme conditions and experimentally probe the interaction between ultrashort soft x-ray pulses and solid targets (metals and their deuterides) at the FLASH free-electron laser where power densities exceeding 10(17) W/cm(2) were reached. Time-of-flight ion spectrometry and crater analysis were used to characterize the interaction. The results show the onset of saturation in the ablation process at power densities above 10(16) W/cm(2). This effect can be linked to a transiently induced x-ray transparency in the solid by the femtosecond x-ray pulse at high power densities. The measured kinetic energies of protons and deuterons ejected from the surface reach several keV and concur with predictions from plasma-expansion models. Simulations of the interactions were performed with a nonlocal thermodynamic equilibrium code with radiation transfer. These calculations return critical depths similar to the observed crater depths and capture the transient surface transparency at higher power densities.
},
  year = {2011},
  journal = {Physical Review E},
  volume = {83},
  pages = {7},
  month = {Jan},
  isbn = {1539-3755},
  doi = {10.1103/PhysRevE.83.016403},
  language = {English},
}