Electron cloud development in the Proton Storage Ring and in the Spallation Neutron Source

M T F Pivi,M A Furman

doi:10.1103/physrevstab.6.034201

Abstract

Author(s): Pivi, M.T.F.; Furman, M.A. | Abstract: We have applied our simulation code POSINST to evaluate the contribution to the growth rate of the electron-cloud instability in proton storage rings. Recent simulation results for the main features of the electron cloud in the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and updated results for the Proton Storage Ring (PSR) at Los Alamos are presented in this paper. A key ingredient in our model is a detailed description of the secondary emitted-electron energy spectrum. A refined model for the secondary emission process including the so-called true secondary, rediffused and backscattered electrons has recently been included in the electron-cloud code.

Highlights

The electron cloud effect may limit the performance of intense proton storage rings, causing a fast instability that may be responsible for proton losses and collective beam motion above a certain current threshold, accompanied by a large number of electrons
It is becoming progressively clear that the electron cloud effect plays an important role in the high-intensity instability which has been observed in the Proton Storage Ring (PSR) at the Los Alamos National Laboratory for more than 13 years
In this article we present simulation results for the Spallation Neutron Source (SNS) and for PSR ring obtained with the electron cloud effect (ECE) code that has been developed at LBNL over the past six years

Summary

INTRODUCTION

The electron cloud effect may limit the performance of intense proton storage rings, causing a fast instability that may be responsible for proton losses and collective beam motion above a certain current threshold, accompanied by a large number of electrons. It is becoming progressively clear that the electron cloud effect plays an important role in the high-intensity instability which has been observed in the Proton Storage Ring (PSR) at the Los Alamos National Laboratory for more than 13 years. This instability is believed to be due to the collective coupling between an electron cloud and the proton beam [1,2]. In particular, the value of the secondary electron yield (SEY) at very low energy, deserve further attention if reliable quantitative predictions are to be achieved for the electron cloud density distribution and its time scales

Sources of electrons

Secondary emission process

RESULTS AND DISCUSSIONS

CONCLUSIONS