|Title||Saturated ablation in metal hydrides and acceleration of protons and deuterons to keV energies with a soft-x-ray laser|
|Publication Type||Journal Article|
|Year of Publication||2011|
|Authors||J. Andreasson, B. Iwan, A. Andrejczuk, E. Abreu, M. Bergh, C. Caleman, A.J Nelson, S. Bajt, J. Chalupsky, H.N Chapman, R.R Faustlin, V. Hajkova, P.A Heimann, B. Hjorvarsson, L. Juha, D. Klinger, J. Krzywinski, B. Nagler, G.K Palsson, W. Singer, M.M Seibert, R. Sobicrajski, S. Tolcikis, T. Tschentscher, S.M Vinko, R.W Lee, J. Hajdu, N. Timneanu|
|Journal||Physical Review E|
|Type of Article||Article|
|Keywords||CLUSTERS, COHERENT, DIFFRACTION, free-electron laser, HYDRODYNAMIC SIMULATION, MATTER, MOLECULAR-SOLIDS, PLASMAS, PULSES, REFLECTION|
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.
|Alternate Title||Phys. Rev. E|
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