Bunching and chopping for tandem accelerators. Part I: Bunching

Abstract

A pulsed system capable of delivering up to a few microamps with a mass range 1–100 u, and with pulse width of bursts of ions approximately 1–2 ns is described. Critical design limitations are discussed to show the overall approach to meet a number of experimental requirements. The system consists of a SNICS negative ion source, a low energy buncher which uses the entire tandem electrostatic accelerator as a drift path to produce bunched ion bursts at the targets or linac entry, and high energy choppers. The buncher consists of a single acceleration gap with aligned removable grids. A detailed analysis is presented of the factors limiting the system performance, with the aim to lessen their effect on the ultimate minimum longitudinal phase space of the ion burst.