The SPEAR RF cavity characterization at Stanford Synchrotron Radiation Laboratory

At the SPEAR storage ring, the 3 GeV stored beam is driven by a five-cell π-mode standing wave cavity operating at 358.54 MHz. The frequency tuning and the field balance between the cells are feedback controlled by movable tuners at the end cells. Another cavity of the same type in the ring can be powered for higher beam current in the future, but it is presently in a standby mode as a backup system. This idle cavity is also used to suppress the beam instability by manually positioning the tuners. For the purpose of cold tests, one PEP-I cavity is being prepared for the RF measurements