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Khumaeni, A.; 宮部 昌文; 赤岡 克昭; 若井田 育夫
no journal, ,
The use of Laser-Induced Breakdown Spectroscopy (LIBS) to heavier atoms requires a higher resolution power of the LIBS spectrometer to identify each emission line separately. Such a spectrometer is less sensitive and thus requires a more intense source of emission. We developed a novel method of microwave-assisted LIBS to produce a high intense plasma. Gadolinium oxide was used as a simulated sample of nuclear fuel material. The microwave generated by a magnetron was coupled to the plasma by the simple loop antenna in the vacuum chamber to enhance the emission. The plasma was induced in various ambient gases including air, Ar, and He gases, and the emission characteristics with microwave are investigated. The enhancement factor for the case with microwave in Ar and He gas are approximately 70 times higher than the case without microwave, while in air environment, the enhancement factor is approximately 40 times. In these cases, it might be assumed that in air case, thermal excitation process by electron collisions might be predominant, and on the other hand, in Ar and He gases, energy transfer from metastable states of these gases might be assumed a major process. To clarify these phenomena, study on excitation process is necessary.
若井田 育夫; 大場 弘則; 赤岡 克昭; 宮部 昌文; 佐伯 盛久; 大場 正規; 伊藤 主税; 加藤 政明
no journal, ,
For the decommissioning of "Fukushima Daiichi Nuclear Power Station" which contained damaged or melt downed core, development of rapid, easy, onsite and in-situ remote diagnostic/analysis techniques under the severe environments such as extremely high radioactive condition, will be strongly required. In order to accomplish these requirements, the concept of probing by light and diagnostic by light with radiation resistant optical fiber will be one of the simple, powerful and applicable choices without sensor hardening technique. Optical Fiber based LIBS probe is constructed, and we have successfully observed some specific spectra from the simulated sample of molten debris made by sintered oxide of Zr and U under water condition, and also observed the spectrum from simulated metal sample under radioactive condition of 10 kGy/h and after total dose of 2 MGy.
大場 弘則; 松本 歩; 利光 正章; 赤岡 克昭; 若井田 育夫
no journal, ,
過酷事故炉内状況調査のために、レーザー誘起ブレークダウン分光(LIBS)と光ファイバー伝送システムを組み合わせた分析技術の開発を進めている。今回は、光ファイバーへの入射エネルギーの向上およびファイバー損傷を抑制するために、LIBS光源にパルス幅60
100nsのロングパルスレーザーを導入し、従来適用約6ns幅のノーマルパルスレーザー適用の場合とのファイバー伝送特性および発光スペクトル出現特性を調べた。その結果、ノーマルパルスでは、光ファイバーの入射損傷しきい値が低くなること、発光強度は大きいが減衰が早いことが確認された。これに対してロングパルスでは、損傷しきい値エネルギーは3倍以上となった。また、発光ピーク強度は低いものの減衰が緩やかであり全発光量は、ノーマルパルスよりも多く、長いレーザーパルスによって生成プラズマが再励起されて発光量が多く観測されていることが示唆された。