Experience with the Pep-II RF System at High Beam Currents

The PEP-II B Factory Low-Level RF System (LLRF) is a fully programmable VXI based design running under an EPICS control environment. Several RF feedback loops are used to control longitudinal coupled-bunch modes driven by the accelerating mode of the RF cavities. This paper updates the performance of the LLRF system as beam currents reach design levels. Modifications which enhance the stability, diagnostics, and overall operational performance are described. Recent data from high current operation is included.