| Budget Amount *help |
¥17,420,000 (Direct Cost: ¥13,400,000、Indirect Cost: ¥4,020,000)
Fiscal Year 2017: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
Fiscal Year 2016: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
Fiscal Year 2015: ¥12,740,000 (Direct Cost: ¥9,800,000、Indirect Cost: ¥2,940,000)
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| Outline of Final Research Achievements |
Normal-conducting RF accelerating cavities, made of copper, are hearts of many particle accelerators, where vacuum arcs in the cavities (breakdowns) could limit accelerator performance; however, we do not know what the real source of cavity breakdowns is. Performing experimental breakdown study based on direct in-situ observation, we demonstrated that cavity breakdown was caused by an explosion of a bright spot which maintained its intensity during high-power operation until the explosion, or by a spot-type explosion not originating from a stable bright spot. In this study, using higher-spec cameras, we have discovered that the bright spots were high-temperature (> 1000 degC) microparticles made of material(s) other than copper, and that spot-type explosions can be understood to be results of impact of flying high-temperature microparticles on cavity surface.
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