Injection/Extraction Kicker for the ALS-U Project

The ALS-II proposal consists in the upgrade of the existing Advanced Light Source at LBNL to a new ultra-low emittance lattice for production of diffraction-limited soft x-rays. In order to compensate for the reduced beam lifetime we intend to operate the machine in continuous top-off mode, where one of several bunch trains is extracted every 30-60 seconds and swapped with a fresh train from the accumulator ring, which is injected on axis without perturbing the circulating beam. In this paper we present a possible design for the injection/extraction kicker based on matched stripline electrodes. The main parameters of such a kicker are discussed in reference to the minimum gap between trains, the storage ring lattice, and the characteristics of a suitable pulser. We also present results from 3D electromagnetic modeling of the proposed kicker performed to evaluate its rise and fall time and field uniformity characteristics.