Minimizing Space Charge Tune Spread and Increasing Beam Quality Parameters with Circular Modes

TL;DR

This paper demonstrates that circular mode beams reduce space charge tune spread in low energy accelerators, leading to improved beam quality and more flexible operation by controlling resonance effects.

Contribution

It introduces the use of circular modes to minimize space charge tune spread, enhancing beam quality and operational flexibility in accelerators.

Findings

Circular mode beams have smaller space charge tune spread than uncorrelated round beams.

Reduced tune spread allows for more flexible tune operation points.

Circular modes improve beam brightness and collision luminosity.

Abstract

Space charge has been a limiting factor for low energy accelerators inducing emittance growth and tune spread. Tune shift and tune spread parameters are important for avoiding resonances, which limit intensity of the beam. Circular modes are round beams with intrinsic flatness that are generated through strong coupling, where intrinsic flatness can be transformed to real space flatness through decoupling. It is understood that flat beams increase beam quality parameters, such as beam brightness and collision luminosity, due to one of the planes' emittance being much smaller than in the other plane, and since both luminosity and beam brightness depend inversely on the beam emittances. We show that circular mode beams manifest smaller space charge tune spread compared to uncorrelated round beams, which allows better control of beam quality. Minimized tune spread allows more flexible operating points on the tune map.