Experimental study based on direct in-situ observation of normal-conducting RF accelerating cavities for elucidating the breakdown-trigger mechanism

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H03671
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: High Energy Accelerator Research Organization
• Principal Investigator: Abe Tetsuo 大学共同利用機関法人高エネルギー加速器研究機構, 加速器研究施設, 准教授 (70370070)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: ブレークダウン / 真空放電 / 加速空洞 / マイクロ波 / 高周波 / 高電界 / 粒子加速 / 加速器

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.

Free Research Field

加速器科学