Calibration of the nonlinear ring model at the Diamond Light Source

R Bartolini,I P S Martin,G Rehm,F Schmidt

doi:10.1103/physrevstab.14.054003

Abstract

Nonlinear beam dynamics plays a crucial role in defining the performance of a storage ring. The beam lifetime, the injection efficiency, and the dynamic and momentum apertures available to the beam are optimized during the design phase by a proper optimization of the linear lattice and of the distribution of sextupole families. The correct implementation of the design model, especially the nonlinear part, is a nontrivial accelerator physics task. Several parameters of the nonlinear dynamics can be used to compare the real machine with the model and eventually to correct the accelerator. Most of these parameters are extracted from the analysis of turn-by-turn data after the excitation of betatron oscillations of the particles in the ring. We present the experimental results of the campaign of measurements carried out at the Diamond storage ring to characterize the nonlinear beam dynamics. A combination of frequency map analysis with the detuning with momentum measurements has allowed for a precise calibration of the nonlinear model that can accurately reproduce the nonlinear beam dynamics in Diamond.

Highlights

The Diamond storage ring has been operating for users since January 2007 [1]
A reliable modelization and control of the linear optics is a crucial prerequisite for progressing with the modelization of the nonlinear beam dynamics
Once a good control of the linear optics was achieved, a campaign of measurements was set up to understand the nonlinear dynamics of the beam in the storage ring

Summary

INTRODUCTION

The Diamond storage ring has been operating for users since January 2007 [1]. The linear optics of the machine was successfully implemented during commissioning using the LOCO package [2]. Once a good control of the linear optics was achieved, a campaign of measurements was set up to understand the nonlinear dynamics of the beam in the storage ring. A necessary step of this investigation is the determination of a reliable model of the nonlinear beam dynamics: the correct implementation of the nonlinear ring model is crucial to maximizing the performance of a synchrotron light source. The aim is not to determine the real model, which would require a perfect knowledge of all elements of the machine, but rather to find an effective model which is in agreement with all measurements Such an effective model can be used to better understand, predict, and control the effects of the nonlinearities of the system.

MEASUREMENTS AND MODELING

BETATRON OSCILLATIONS FROM TURN-BY-TURN BPM DATA

Findings

CONCLUSION