学術雑誌論文 Fiber-optic laser-induced breakdown spectroscopy of zirconium metal in the air: The special feature of the plasma produced by the long-pulse laser

Matsumoto, Ayumu  ,  Oba, Hironori  ,  Toshimitsu, Masaaki  ,  Akaoka, Katsuaki  ,  Ruas, Alexandre  ,  Sakka, Tetsuo

内容記述
The decommissioning of the Tokyo Electric Power Company (TEPCO) Fukushima Daiichi Nuclear Power Plant is an essential issue in nuclear R&D. Fiber-optic laser-induced breakdown spectroscopy (Fiber-optic LIBS) could be used for in-situ elemental analysis of the inside of the damaged reactors. To improve the performances under the difficult conditions, using a long-pulse laser can be an efficient alternative. In this work, the emission spectra of zirconium metal in the air obtained for a normal-pulse laser (6 ns) and a long-pulse laser (100-ns) (wavelength: 1064 nm, pulse energy: 12.5 mJ, spot diameter: 0.35 mm) are compared to investigate the fundamental aspects of fiber-optic LIBS with the long-pulse laser. The spectral feature is considerably different: when the long-pulse laser is used, the atomic and molecular emission is remarkably enhanced. The enhancement of the atomic emission at the near infrared (NIR) region would lead to the observation of emission lines with minimum overlapping even in the high-radiation fields. To understand the differences in the spectra induced respectively from the normal pulse laser and the long pulse laser, photodiode signals, time-resolved spectra, plasma parameters, emission from the ambient air, and emission regions are investigated, which show the particular characteristics of the plasma produced by the long-pulse laser.

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