The Three-Dipole Kicker Injection Scheme for the ALS-U Accumulator Ring

TL;DR

This paper presents a novel three-dipole kicker injection scheme for the ALS-U accumulator ring, enabling efficient on-axis swap-out injection with minimal beam disturbance in a constrained aperture environment.

Contribution

The paper introduces the 3DK injection scheme, a new method utilizing three dipole kickers tailored for the specific requirements of the ALS-U accumulator ring.

Findings

Designed and optimized the 3DK scheme for the accumulator ring.

Evaluated the scheme's effectiveness for booster-to-accumulator injection.

Demonstrated compatibility with the ring's aperture constraints.

Abstract

The ALS-U light source will implement on-axis single-train swap-out injection employing an accumulator between the booster and storage rings. The accumulator ring design is a twelve period triple-bend achromat that will be installed along the inner circumference of the storage-ring tunnel. A non-conventional injection scheme will be utilized for top-off off-axis injection from the booster into the accumulator ring meant to accommodate a large $\sim 300$~nm emittance beam into a vacuum-chamber with a limiting horizontal aperture radius as small as $8$ mm. The scheme incorporates three dipole kickers distributed over three sectors, with two kickers perturbing the stored beam and the third affecting both the stored and the injected beam trajectories. This paper describes this ``3DK'' injection scheme and how it fits the accumulator ring's particular requirements. We describe the design and optimization process, and how we evaluated its fitness as a solution for booster-to-accumulator ring injection.