Beam coupling phenomena in fast kicker systems

Abstract

Beam coupling phenomena have been observed in most fast kicker systems through out Brookhaven ColliderAccelerator complex. With ever-higher beam intensity, the signature of the beam becomes increasingly recognizable. The beam coupling at high intensity produced additional heat dissipation in high voltage modulator, thyratron grids, thyratron driver circuit sufficient to damage some components, and causes trigger instability. In this paper, we will present our observations, basic coupling mode analysis, relevance to the magnet structures, issues related to the existing high voltage modulators, and considerations of the future design of the fast kicker systems.

Fast Extracted Beam FEB for the g-2 Experiment

“…When the amplitude of the bumped beam and the B-field amplitude of the H10-septum is reached, the ARF.FEBREQ.DELAY trigger is generated at ~28 msec after each FEB-request trigger. The ARF.FEBREQ.DELAY trigger 13 energizes a circuit that comes under the name "kicker trigger generator" which performs the following functions: a) Just after the arrival of the ARF.FEBREQ.DELAY, the "kicker-triggergenerator" synchronizes the AGS bucket (of the first injected bunch from the AGS-Booster), with the immediate next "zero-crossing" of the RF signal which is also fed into the "kicker trigger generator" circuit. This synchronization of the "zero-crossing" of the RF signal is required in order to keep track of the extracted bunches in the AGS.…”

“…For high intensity proton operations the high beam current induces a significant voltage on the coil of the G10-kicker. This voltage, in turn, generates a noise [13] on the "G10-kicker trigger" pulse which causes an earlier firing of the kicker, than what is expected by the "fine delay". A time distribution of the G10 firing events, as measured with respect to the "G10-kickertrigger", is shown in figure 13.…”

Design considerations of fast kicker systems for high intensity proton accelerators

“…increased energy, the arc dipoles would operate at 7020A and have a measured sextupole component [3] of bz = -0.64 x 10-%-n-2.…”

Design considerations of fast kicker systems for high intensity proton accelerators

“…A high-intensity beam can interact with a kicker magnet [3], and produce undesired effects such as beam losses and instabilities. It also poses a potential danger to the kicker system itself.…”