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Miyabe, Masabumi; Oba, Masaki; Akaoka, Katsuaki; Kato, Masaaki*; Hasegawa, Shuichi*; Wakaida, Ikuo
Applied Physics A, 126(3), p.213_1 - 213_10, 2020/03
Times Cited Count：6 Percentile：38.16(Materials Science, Multidisciplinary)The dynamic behavior of an ablation plume in low pressure rare gas ambient was investigated with laser-induced fluorescence imaging spectroscopy for three refractory metals, i.e. titanium, zirconium and hafnium. A comparison of the plume expansion behaviors for the species of these elements revealed an atomic weight effect on the plume structure formation. A hemispherical thin layer and cavity structure reported previously for gadolinium were observed also for these elements. It was found that the plume size increases as well as the layer thickness decreases with increasing atomic weight. For ground state atoms of Ti, substantial amount of atoms were observed even at the center of the plume. Also, the persistence of the Ti atomic plume was as long as 300 
s, which was significantly longer than the other species studied. Furthermore, the mass-dependent elemental separation was observed in the ablation plume produced from a multielement sample. These results suggest that the observed plume structure arises from the ion-electron recombination process and the recoil of the ablated species during the multiple collisions with gas atoms.
Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Khumaeni, A.*; Kato, Masaaki; Wakaida, Ikuo
Spectrochimica Acta, Part B, 110, p.101 - 117, 2015/08
Times Cited Count：25 Percentile：81.83(Spectroscopy)The dynamic behavior of an ablation plume in ambient gas has been investigated by laser-induced fluorescence imaging spectroscopy. The second harmonic beam from an Nd:YAG laser (0.5-6J/cm
) was focused on a sintered oxide pellet or a metal chip of gadolinium. The produced plume was subsequently intersected with a sheet-shaped UV beam from a dye laser so that time-resolved fluorescence images were acquired with an intensified CCD camera at various delay times. The obtained cross-sectional images of the plume indicate that the ablated ground state atoms and ions of gadolinium accumulate in a hemispherical contact layer between the plume and the ambient gas, and a cavity containing a smaller density of ablated species is formed near the center of the plume. At earlier expansion stage, another luminous component also expands in the cavity so that it coalesces into the hemispherical layer. The splitting and coalescence for atomic plume occur later than those for ionic plume. Furthermore, the hemispherical layer of neutral atoms appears later than that of ions; however, the locations of the layers are nearly identical. This coincidence of the appearance locations of the layers strongly suggests that the neutral atoms in the hemispherical layer are produced as a consequence of three-body recombination of ions through collisions with gas atoms. The obtained knowledge regarding plume expansion dynamics and detailed plume structure is useful for optimizing the experimental conditions for ablation-based spectroscopic analysis.
Oba, Hironori; Nishimura, Akihiko; Ogura, Koichi; Shibata, Takemasa
JAERI-Research 2000-033, 17 Pages, 2000/08
JAERI-Research-2000-033.pdf:0.65MB
no abstracts in English
Ichinose, Yuji; *; Kawanishi, Shunichi; *; *
Journal of Physical Chemistry A, 103(40), p.7923 - 7926, 1999/10
Times Cited Count：22 Percentile：70.26(Chemistry, Physical)no abstracts in English
Takahashi, Yoshio*; Kimura, Takaumi; Kato, Yoshiharu; Minai, Yoshitaka*
Environmental Science & Technology, 33(22), p.4016 - 4021, 1999/00
Times Cited Count：46 Percentile：74.36(Engineering, Environmental)no abstracts in English
Takahashi, Yoshio*; Kimura, Takaumi; Kato, Yoshiharu; *; *; *
Journal of Radioanalytical and Nuclear Chemistry, 239(2), p.335 - 340, 1999/00
Times Cited Count：15 Percentile：72.22(Chemistry, Analytical)no abstracts in English
Takahashi, Yoshio*; Kimura, Takaumi; Kato, Yoshiharu; *; *
Radiochimica Acta, 82, p.227 - 232, 1998/00
no abstracts in English
Takahashi, Yoshio*; Kimura, Takaumi; ; *; *
Journal of Radioanalytical and Nuclear Chemistry, Letters, 212(1), p.11 - 21, 1996/00
no abstracts in English
Miyabe, Masabumi; Oba, Masaki; Jung, K.; Akaoka, Katsuaki; Wakaida, Ikuo
no journal, ,
In order to analyze isotopic composition of fuel debris generated in melted reactor core, a remote analytical method is developed based on laser ablation technique. In this method, the interaction between ablated and gas species affects time evolution of the plume structure, which also affects on analytical performance. Thus we investigate time evolution of ablated and gas species using resonance fluorescence and absorption techniques. As a result, it was found that the interaction between gas and ablated species leads complicated three dimensional structure. In particular, in the case of atmospheric air condition, it was found that many particulates and clusters are produced at the contact layer between gas and plume, and the neutral atoms stays near the center of the clusters. These findings is of great importance for future development of various laser-ablation-based analytical techniques.
