Beam-dynamic effects of a droop in an induction accelerating voltage

Abstract

Proof-of-principle experiments on the induction synchrotron concept are scheduled using the KEK 12-GeV proton synchrotron, in which rf bunches and a superbunch will be accelerated with a long step voltage generated in the induction accelerating gaps. An unavoidable droop in the induction voltage gives an additional focusing or defocusing force in the longitudinal direction. It largely deforms the barrier bucket confining the superbunch, leading to a nonuniform particle distribution. The effects are serious in an induction synchrotron with a transition energy. Longitudinal emittance blowup beyond the transition energy is not acceptable. The necessity of compensating for the droop is discussed.

Induction acceleration scenario from an extremely low energy in the KEK all-ion accelerator

“…The droop has serious effects from the beam dynamics point of view [8]. A longer acceleration voltage is required for the KEK-AIA for proper acceleration of particles.…”

Developments on Next-Generation Beam Handling of High-Energy Particles by using Non-linear Characteristics

“…The droop was treated as the bad effect phenomenon [14], but it is very useful to accelerate and confine the high-energy particles like as rf devices by the famous combined function theory of synchrotron motion. On the other hand, the roles can be separated by simple compensation of capacitance in electric circuit.…”

Longitudinal confinement and matching of an intense electron beam

“…14 This enabled them to get around the limitation of the available longitudinal phase space for acceleration from 0.5 to 12 GeV. 14,15 The University of Maryland Electron Ring ͑UMER͒ is a high intensity circular machine that is dedicated to the study of long path length space-charge-dominated beam physics on a small scale. 16,17 In this paper, we report on the significant improvement in lifetime of a 0.52 mA bunch in UMER, to over a thousand turns ͑Ͼ11.52 km͒.…”