Circular Modes for Linacs

TL;DR

This paper explores the design of rotation invariant systems that enable the transport and preservation of circular modes in linear accelerators, facilitating beam flatness control and high brightness applications.

Contribution

It introduces rotation invariant designs that maintain circular modes during acceleration, allowing conversion to flat beams or injection into rings.

Findings

Circular modes can be transported while maintaining circularity.

Rotation invariant designs preserve mode circularity during acceleration.

Intrinsic flatness can be converted to real space flatness or preserved as round beams.

Abstract

Circular mode beams are beams with non-zero angular momentum and strong inter-plane coupling. This coupling can be achieved in linear accelerators (linacs) through magnetization of electrons or ions at the source. Depending on the magnetization strength, the intrinsic eigenmode emittance ratio can be large, which produces intrinsic flatness. This flatness can either be converted to real space flatness or can be maintained as round coupled beam through the system. In this paper, we discuss rotation invariant designs that allow circular modes to be transported through the lattice while accelerating the beam and maintaining its circularity. We demonstrate that with rotation invariant designs the circularity of the mode can be preserved as round beam while maintaining intrinsic flatness to be converted to flat beam for high brightness or injected into a ring.