Quasi-equilibrium in charge-state evolution for carbon, sulfur, and tungsten ions after passing through carbon foils

29th International Conference on Photonic, Electronic, and Atomic Collisions

Imai, Alex M.^1 ; Sataka, M.^2,3 ; Matsuda, M.^2 ; Okayasu, S.^2 ; Kawatsura, K.^4 ; Takahiro, K.^5 ; Komaki, K.^6 ; Shibata, H.^1,7 ; Nishio, K.^2

Department of Nuclear Engineering, Kyoto University, Nishikyo, Kyoto

615-8540, Japan^1

Japan Atomic Energy Agency (JAEA), Ibaraki, Tokai

319-1195, Japan^2

Research Facility Center for Science and Technology, University of Tsukuba, Ibaraki

305-8573, Japan^3

Kansai Gaidai University, Osaka, Hirakata

573-1001, Japan^4

Kyoto Institute of Technology, Sakyo, Kyoto, 606-8585, Japan^5

RIKEN, Wako, Saitama 351-0198, Japan^6

Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, 567-0047, Japan^7

关键词: Carbon foils;    Charge state;    Equilibrium value;    Foil thickness;    Quasi equilibrium;    Shell effects;    Target thickness;    Tungsten ions;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/635/2/022040/pdf
DOI  :  10.1088/1742-6596/635/2/022040

来源: IOP

【 摘 要 】

Charge-state evolution of 2.0 MeV/u carbon, sulfur, and 1.0 MeV/u tungsten ions after carbon-foil penetration has been studied experimentally in the foil thickness range covering both pre- and after the equilibrium. It was observed for the first time that mean charge-states for Sq+(q = 6-14) initial ions evolved to coincide in 12.3 at a target thickness of 6.9 μg/cm2, showing a "quasi-equilibrium," and further evolved simultaneously to a real equilibrium value of 12.68, whereas those for Sq+(q = 15, 16) initial ions evolved directly to the real equilibrium, without through the "quasi-equilibrium," until the target thickness was increased to 100 μg/cm2. Such kind of shell-effect was observed also for C-ions, and could be qualitatively reproduced by some simulations.