A fast chopper for programmed population of the longitudinal phase space of the AGS

Abstract

JJcceived by OSTl A fast beam chopper has been hnLit that can produce an arbitrary pulse program of the ?.00 MeV II" beam for synchronous Injection tnto moving rf bucketa In Cht ACS. The chopper will eliminate rC capture losses and can be used to tailor Che initial distribution in longitudinal phase space by varying the pulse parameters, width and phase, on a bunchby-bunch time scale, during multi-turn Injection. The chopper also serves as a studioa loul since Lu can provide controllable beam Intensity with fixed longitudinal emlttance (nnd conversely) uml/or missing buueheu. It LH 'in uleciroHLuL tc del Leel Lou device with 15 pairs of plates located above jml below the 35 keV H~ beam between the Ion source and the Itl'Q | > re Injector. The pLutuH ure «pm:»;il I'd mm apart in die bourn direction oml connected »u u nlowwave structure by coaxial cables. They are driven to * 760 V by dc-coupled JJUIHC guuurtitorv. lle.im current rtae and Hall times are ICHH tlwu 10 uu. * W o r k p t M T i i r n u u l 11IIII«• r (.lie / H I M | > 1I't'ii n f t i n * II* Department of Energy.

A single bunch RFQ system for heavy ions

“…To deflect single beam bunches one has to apply transversal electric fields e. g. with a plate capacitor. The electric fields can be produced by pulsed static deflectors with short rise time (τ < 1/2 f, f = accelerator frequency) [2], where the deflection angle is proportional to the applied electric field and the deflector length l or by an rf-deflector which can be driven by resonant structures. So it is possible to reach higher voltages then in static deflectors, because the voltages of amplifiers with short rise times are limited to approximately 1 kV.…”