An ultimate storage ring lattice with vertical emittance generated by damping wigglers

TL;DR

This paper proposes a novel method for generating round beams in ultimate storage rings using vertical damping wigglers, which simplifies the lattice design and achieves low emittance with realistic magnet parameters.

Contribution

It introduces the use of vertical damping wigglers to generate vertical emittance, avoiding complex coupling and demonstrating a practical lattice design compatible with existing facilities.

Findings

Horizontal emittance of 22.3 pm achieved

Vertical emittance of 10.3 pm achieved

Lattice design uses realistic magnet gradients

Abstract

We discuss the approach of generating round beams for ultimate storage rings using vertical damping wigglers (with horizontal magnetic field). The vertical damping wigglers provide damping and excite vertical emittance. This eliminates the need to generate large linear coupling that is impractical with traditional off-axis injection. We use a PEP-X compatible lattice to demonstrate the approach. This lattice uses separate quadrupole and sextupole magnets with realistic gradient strengths. Intrabeam scattering effects are calculated. The horizontal and vertical emittances are 22.3 pm and 10.3 pm, respectively, for a 200 mA, 4.5 GeV beam, with a vertical damping wiggler of a total length of 90 meters, peak field of 1.5 T and wiggler period of 100 mm.