ＫＥＫ‐Ｂファクトリー用超伝導高周波加速空洞―大電流ビーム加速への応用―:—大電流ビーム加速への応用—

概要

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KEKB is one of the most challenging accelerators in the world aiming to achieve the peak luminosity of 1×1034 cm-2s-1 for the study of B-meson physics. To achieve such a high luminosity, ampere-class beams of electron and positron have to be accumulated in the 8 GeV-ring (HER) and the 3.5 GeV-ring (LER) separately, and be controlled precisely to collide each other in the BELLE detector located at the collision point. These intense beams need the accelerating RF cavities that have sufficiently damped higher modes (HOM) not to excite uncontrollable beam instabilities caused by the field induced by the beam. Therefore new accelerating cavities have been developed in KEKB for both superconducting (SC) and normal conducting (NC) cavities. Since the beginning of machine commissioning in 1998, the peak luminosity has been improved gradually as increasing the beam intensity of both rings, and achieved the peak luminosity of 1.4×1034 cm-2s-1 with the beams of 1.2 A in HER and 1.6 A in LER so far. In HER, eight SC damped cavities have been installed together with twelve NC cavities, and share the RF voltage of 11 MV and the beam power of 2.4 MW. This superior accelerating performance has opened up a new application of high intensity acceleration for the SC cavity.
公益社団法人低温工学・超電導学会 (旧社団法人低温工学協会)の論文