The abort kicker system for the PEP-II storage rings at SLAC

The PEP-II project has two storage rings. The HER (high energy ring) has up to 1.48 A of election beam at 9 GeV, and the LER (low energy ring) has up to 2.14 A of positron beam at 3.1 GeV. To protect the HER and LER beam lines in the event of a ring component failure, each ring has an abort kicker system which directs the beam into a dump when a failure is detected. Due to the high current of the beams, the beam kick is tapered from 100% to 80% in 7.33 /spl mu/S (the beam transit time around the ring). This taper distributes the energy evenly across the window, which separates the ring from the beam dump such that the window is not damaged. The abort kicker trigger is synchronized with the ion clearing gap of the beam allowing for the kicker field to rise from 0-80% while there is no beam in the kicker magnet. Originally the kicker system was designed for a rise time of 370 nS [J.E. de Lamare, et al., 1997], but because the ion clearing gap was reduced in half, so was the rise time requirement for the kicker. This report discusses the design of the system interlocks, diagnostics, and modulator with the modifications necessary to accommodate an ion clearing gap of 185 nS.