A superconducting Landau accelerator module for Bessy II

The installation of a 3rd harmonic Landau accelerator module is planned at BESSY II to improve the beam lifetime. The passive cavity shall provide an accelerating voltage up to 500 kV for beam currents from 10 to 500 mA. A CESR Phase-III cavity [1], scaled to 1.5 GHz, will be used. The cavity design provides strong damping of higher-order modes by ferrite loads on the beam tubes. A new module, constrained to fit into a very limited space at BESSY, is described here. It includes a piezo-electric tuner that allows amplitude control within 1%. Nonstandard modes of operation, such as normal-conducting stand-by operation and thermal breakdown are also discussed.