Wide frequency-range acceleration using second harmonic RF bucket in fixed field accelerators

TL;DR

This paper introduces a new acceleration method for fixed-field accelerators that combines harmonic RF buckets to achieve wide frequency-range acceleration with fewer frequency sweeps.

Contribution

It proposes a novel RF bucket sequencing scheme in FFAs, demonstrated through simulations, reducing frequency sweep range and operational complexity.

Findings

Successful simulation of the proposed acceleration scheme.

Operational conditions for stable second harmonic RF bucket.

Reduced total RF frequency sweep range.

Abstract

We propose a novel acceleration scheme for fixed-field accelerators (FFAs), in which RF buckets with harmonic numbers $h = 1$ and $h = 2$ are time-sequenced to form a single, continuous acceleration path. This approach completes acceleration in two RF frequency sweeps, thereby reducing the total frequency sweep range and shortening the repetition period. The feasibility of this method is demonstrated through longitudinal simulations based on parameters of the FFA at the Institute for Integrated Radiation and Nuclear Science, Kyoto University (KURNS). We also establish operational conditions under which the second harmonic rf bucket remains stable and practically usable.