Application of Superconducting Thin Films to RF Cavities
Advances in Superconductivity IV
Recently, the application of superconducting (SC) cavities to collider-type particle factories is becoming of great importance in the field of particle accelerators. The use of SC accelerating cavities in factories is attractive for a high accelerating voltage, a high stored energy and low impedance. There are two factory projects which have SC cavities under construction: the asymmetric energy B-factory at KEK (KEKB) and the luminosity upgrade of CESR to phase III. In addition, SC cavities
... on, SC cavities will be used in two future projects: the Beijing τ-charm factory at IHEP (BTCF) and the large hadron collider at CERN (LHC). These factories are required to store a high beam current of several amperes with a short bunch length in order to achieve a very high luminosity in the range of 5x10 32 to 10 34 /cm 2 s. In applying SC cavities to factories, many challenging tasks have been set, most of which come from extremely heavy beamloading. In particular, key issues are the heavy damping of HOMs, the stability of the accelerating mode and high power handling capability. Extensive efforts have been made to develop SC damped accelerating cavities to meet the heavy demands; successful results have been obtained at bench tests and beam tests with beam currents of more than 500 mA. Another attractive application of SC cavities to factories is a SC crab cavity. The R&D of SC crab cavities is in progress at KEK to prepare for the potential need of the crab-crossing scheme in KEKB.