A wide band slot-coupled beam sensing electrode for the Advanced Light Source (ALS)

An exponentially tapered stripline provides nearly constant coupling impedance vs. frequency and yields superior frequency-domain performance. The authors report on the construction of an exponentially tapered, slot-coupled stripline which was relatively easy to construct and has the desired frequency response in terms of broadband performance. Stripline electrodes are commonly used in particle accelerators as beam pickups and kickers. Part of the ALS booster synchrotron beam diagnostics system includes three stripline assemblies: a kicker and two pickups. Exponentially tapered striplines were desired in the pickups because of their superior frequency domain performance. With prototypes it was difficult to hold mechanical dimensions which were important for impedance reasons. The transition from coaxial to stripline geometry was also difficult. To overcome these problems the slot-coupled stripline was developed. The theory, the slot-coupled pickup, the beam pickup mechanical details, and laboratory tests on the pickups and kickers are discussed.<>