Practical aspects of transverse resonance island buckets at the Cornell Electron Storage Ring: design, control and application

TL;DR

This paper presents a new method for controlling transverse resonance island buckets (TRIBs) in the Cornell Electron Storage Ring, improving beam stability and aperture, with demonstrated simulations and experiments.

Contribution

A novel optimization approach reduces control variables from 76 to 8 and enables precise manipulation of TRIBs in an electron storage ring.

Findings

Effective control of TRIBs demonstrated through simulations and experiments.

Method improves dynamic and momentum apertures in the storage ring.

New scheme to consolidate particles into a single island.

Abstract

In an accelerator, the nonlinear behavior near a horizontal resonance line ($n\nu_x$) usually involves the appearance of stable fixed points (SFPs) in the horizontal phase space, also referred to as transverse resonance island ``buckets" (TRIBs). Specific conditions are required for TRIBs formation. At the Cornell Electron Storage Ring, a new method is developed to improve the dynamic and momentum apertures in a 6-GeV lattice as well as to preserve the conditions for TRIBs formation. This method reduces the dimension of variables from 76 sextupoles to 8 group variables and then utilizes the robust conjugate direction search algorithm in optimization. Created with a few harmonic sextupoles or octupoles, several knobs that can either rotate the TRIBs in phase space or adjust the actions of SFPs are discussed and demonstrated by both tracking simulations and experimental results. In addition, a new scheme to drive all particles into one single island is described. Possible applications using TRIBs in accelerators are also discussed.