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 CW 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. In principle, this fireball breakdown can occur in any normal-conducting HG accelerating structures. On the other hand, SuperKEKB accelerator 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, where fireballs could interplay through the accelerator. In this presentation, the presenter will explain the fireball hypothesis and show some plans to perform further high-power tests of RF cavities to demonstrate the hypothesis and to better understand the breakdown mechanism.
