Novel technique for injecting and extracting beams in a circular hadron accelerator without using septum magnets

Andrea Franchi,Massimo Giovannozzi

doi:10.1103/physrevstab.18.074001

Andrea Franchi, Massimo Giovannozzi

Open Access

https://doi.org/10.1103/physrevstab.18.074001

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Abstract

With a few exceptions, all on-axis injection and extraction schemes implemented in circular particle accelerators, synchrotrons, and storage rings, make use of magnetic and electrostatic septa with systems of slow-pulsing dipoles acting on tens of thousands of turns and fast-pulsing dipoles on just a few. The dipoles create a closed orbit deformation around the septa, usually referred to as an orbit bump. A new approach is presented which obviates the need for the septum deflectors. Fast-pulsing elements are still required, but their strength can be minimized by choosing appropriate local accelerator optics. This technique should increase the beam clearance and reduce the usually high radiation levels found around the septa and also reduce the machine impedance introduced by the fast-pulsing dipoles. The basis of the technique is the creation of stable islands around stable fixed points in horizontal phase space. The trajectories of these islands may then be adjusted to match the position and angle of the incoming or outgoing beam.

Highlights

The injection of charged particle beams in most modern synchrotrons and storage rings, denoted hereafter as accelerators, from an upstream injector device is based on the combined use of a septum deflector and a system of pulsing dipoles
The aim of this paper is to show the principles rather than one detailed implementation study, which would be based on a concrete design with specific performance goals
It can be argued that for multiturn extraction (MTE), multiturn injection (MTI) or single-turn extraction (STE), single-turn injection (STI) the ring can be better represented as a transfer line, questioning the usefulness of the approach proposed here, which is based on periodic structures

Summary

Introduction

The injection of charged particle beams in most modern synchrotrons and storage rings, denoted hereafter as accelerators, from an upstream injector device is based on the combined use of a septum deflector and a system of pulsing dipoles (bumpers and kickers). Both are necessary since the nominal circular orbit defined by the ring main bending magnets cannot match that of the incoming beam [1]. Bumpers and kickers generate an orbit closed bump such that, at the septum exit, both the position and the angle of the bump match those of the incoming beam. All on-axis injections of hadron beams into circular accelerators are based on this scheme, the only exception being that of the charge-exchange H− injection [2,3]

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