Fiber-optic laser-induced breakdown spectroscopy of solid samples in air with long nanosecond pulse

長いナノ秒パルスによる大気中固体試料のファイバー伝送レーザー誘起ブレークダウン分光

松本 歩; 大場 弘則  ; 利光 正章; 赤岡 克昭 ; 若井田 育夫  

Matsumoto, Ayumu; Oba, Hironori; Toshimitsu, Masaaki; Akaoka, Katsuaki; Wakaida, Ikuo

To observe the inside of the damaged nuclear reactors in Fukushima Daiichi Nuclear Power Station, a fiber-optic laser-induced breakdown spectroscopy (LIBS) instrument has been developed. Recently, a long pulse laser is expected to avoid the damage of an optical fiber probe and to enable the transmission of higher energy. However, the laser ablation process of solid samples in air with the long pulse has not been clarified enough. In this study, temporal variations of the plasma emission were measured with short and long nanosecond pulses. As a result, the delay time from the pulse irradiation to the plasma generation and the temporal profile of the emission intensity are considerably different depending on the pulse duration. The difference of the plasma formation process during the pulse irradiation may affect the LIBS signal observed after several microseconds.