Study of Electron Beam Instabilities in the Storage Ring at the Canadian Light Source Using the Transverse Feedback System
Date
2025-06-03
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0009-0009-6582-8611
Type
Thesis
Degree Level
Masters
Abstract
The Canadian Light Source (CLS) 2.9 GeV electron storage ring circulates hundreds of
approximately 1 nC bunches of charge in an electromagnetic trap. The oscillatory motion of
these electron bunches is coupled through the electromagnetic interaction with the vacuum
chamber in which they circulate. If this motion is left uncontrolled, this coupling can
result in unstable motion. These so called coupled bunch instabilities can lead to the
beam size enlarging or worst case beam loss. Consequently, mitigation strategies against
these coupled bunch instabilities have become a critical element of modern synchrotron
design. As part of their mitigation strategy, the CLS utilizes a Transverse Feedback System
(TFBS), to identify and correct against these instabilities via active damping where they
arise. The TFBS also doubles as a diagnostic tool, enabling the study of these coupled
bunch instabilities. This research project studied the properties of the coupled bunch
instabilities in the CLS storage ring using simulations and experiments. Experiments have
been performed using the TFBS to measure the exponential damping rates of the induced
beam oscillations. To study these beam instabilities, experiments were largely done via
adjustment of in-vacuum insertion device gap heights, which changes the vertical vacuum
chamber profile height. Early experiments focused on grow-damp methods, where the
feedback loop is briefly disabled to allow instabilities to grow before being damped by the
system. To yield new results, later experiments involved excite-damp methods, where the
beam is deliberately excited to study damping rates. To better understand and compare
against experiment results, eigenmode and equivalent-circuit simulations of the Brockhouse
beamline’s in-vacuum wiggler insertion device have been performed. Characterizing and
controlling the instabilities found in this project will be a limiting factor for higher storage
ring beam current or the addition of new insertion devices at the CLS in the future.
Description
Keywords
Physics, CLS
Citation
Degree
Master of Science (M.Sc.)
Department
Physics and Engineering Physics
Program
Physics