Single-gap multi-harmonic buncher for NSC pelletron

A single-gap multi-harmonic buncher, developed in collaboration with Argonne National Laboratory, has been installed in the pre-acceleration region of NSC Pelletron. This buncher is required for injecting bunched beam into the booster LINAC, presently under construction. A saw-tooth voltage generated across a single gap formed by a closely spaced pair of grids is used for bunching the dc ion beam produced by the Pelletron accelerator. This saw-tooth voltage is produced by adding a sine wave with its three higher harmonics in proper phase and amplitude. 28Si beam has been bunched successfully using this buncher. The best FWHM of the bunched beam was 1.5 ns and the maximum efficiency of bunching was 50%. The bunching voltage had no steering effect on the beam. (author)