Speaker
Description
There are various hypotheses for vacuum-breakdown trigger mechanisms in normal-conducting accelerating structures. It has been experimentally turned out that the dominant trigger of RF breakdowns in normal-conducting UHF continuous-wave cavities is a hot micro-particle with a high sublimation point [Phys. Rev. Accel. Beams 21, 122002 (2018)], later named a "fireball" by this presenter. On the other hand, SuperKEKB accelerator at KEK, Japan, is suffering from a serious obstacle of sudden beam losses in the collider rings, that limits the luminosity improvement. Recently, this presenter has proposed a hypothesis that the same mechanism as in the fireball breakdown can be a trigger of the sudden beam losses at SuperKEKB. In this presentation, the presenter will explain the fireball hypothesis and its experimental demonstration, leading to better understanding of the fireball breakdown mechanism.
