Real-Time Imaging of Adsorbed Tritium(?) : Potential of Microchannel Plate-

To investigate microscopic processes of trapping and diffusion of tritium on/through materials, autoradiography has been widely applied. This technique, however, gives us only qualitative information. One aim of this study is to examine the potential of a microchannel plate for in-situ measurements of the amounts of adsorbed tritium and its distribution on sample surfaces. Microchannel plates (MCP, Hamamatsu Photonics Ltd.) were mounted in an oil-free ultra-high vacuum chamber. By use of a MCP with a phosphorescent anode plate, the image of the thermal electrons from a hot filament was observed. When the applied voltage and electron fluence were above 1.5 kV and 10e-/sec, respectively, it was possible to obtain in-situ image of hot electrons with real-time. These results indicate that tritium of over 10-9 Ci can be detected. This means that tritium of 10-3 in the coverage is detectable. Therefore, the above-mentioned imaging apparatus is applicable to in-situ measurements of the distribution of adsorbed tritium. In addition, the combination of the lens system and image processing one will provide us a powerful technique to investigate the distribution of tritium adsorbed on materials and its motion