Multibunch beam extraction using the strip-line kicker at the KEK Accelerator Test Facility

Abstract

The International Linear Collider (ILC) damping ring (DR) injection and extraction kickers have a very special role: the bunch spacing 189–480 ns is compressed to 3–9 ns when injected into the DR and then decompressed to 189–480 ns when leaving the DR. The kickers act as a bunch-by-bunch beam manipulator to compress and decompress the bunch spacing into/from the DR. They require a fast rise/fall time (3–9 ns) and a high repetition rate (6–2 MHz). Among the candidate technologies, the multiple strip-line kicker system is the most likely to realize the specifications for the ILC reference design. A beam extraction experiment with a prototype strip-line kicker has been carried out at the KEK Accelerator Test Facility (ATF). The kicker is composed of two units of 60-cm-long strip-line electrodes. The multibunch beam (30 bunches spaced at 5.6 ns) stored in the DR was extracted successfully with a bunch spacing of 308 ns. The measured stability of the kick angle was 3.5×10^{-4}. Some, but not all, parameters of the tested kicker meet the ILC-DR injection/extraction kicker requirements.