Controlling beam trajectory and transport in a tapered helical undulator

In this paper we present a detailed discussion of the helical undulator system developed for high extraction efficiency experiments in the tapered-enhanced stimulated superradiant amplification regime. The design is based on permanent magnet technology and comprises two Halbach arrays orthogonally o...

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Main Authors: A. Fisher, J. Jin, P. Musumeci
Format: Article
Language:English
Published: International Union of Crystallography 2025-03-01
Series:Journal of Synchrotron Radiation
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Online Access:https://journals.iucr.org/paper?S1600577524012463
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author A. Fisher
J. Jin
P. Musumeci
author_facet A. Fisher
J. Jin
P. Musumeci
author_sort A. Fisher
collection DOAJ
description In this paper we present a detailed discussion of the helical undulator system developed for high extraction efficiency experiments in the tapered-enhanced stimulated superradiant amplification regime. The design is based on permanent magnet technology and comprises two Halbach arrays orthogonally oriented and shifted by 90° with respect to each other. When used in low energy beamlines for THz generation, the electron beam trajectory and transport are particularly sensitive to the undulator off-axis fields so that it becomes important to complement on-axis field measurements with analysis and tuning of the higher-order field components. Here we describe how the pulsed wire measurement technique can be effectively used to retrieve on- and off-axis magnetic field characteristics of the undulator. A simple two-dipole model is developed to guide the final adjustments to the permanent magnet positions along the array to tune the quadrupole and sextupole components of the field.
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publisher International Union of Crystallography
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spelling doaj-art-b9ffbe0f9260463ca57c2cae597e1d232025-08-20T02:58:36ZengInternational Union of CrystallographyJournal of Synchrotron Radiation1600-57752025-03-0132233133910.1107/S1600577524012463zhu5004Controlling beam trajectory and transport in a tapered helical undulatorA. Fisher0J. Jin1P. Musumeci2Department of Physics and Astronomy, University of California Los Angeles, 475 Portola Plaza, Los Angeles, CA 90095, USADepartment of Physics and Astronomy, University of California Los Angeles, 475 Portola Plaza, Los Angeles, CA 90095, USADepartment of Physics and Astronomy, University of California Los Angeles, 475 Portola Plaza, Los Angeles, CA 90095, USAIn this paper we present a detailed discussion of the helical undulator system developed for high extraction efficiency experiments in the tapered-enhanced stimulated superradiant amplification regime. The design is based on permanent magnet technology and comprises two Halbach arrays orthogonally oriented and shifted by 90° with respect to each other. When used in low energy beamlines for THz generation, the electron beam trajectory and transport are particularly sensitive to the undulator off-axis fields so that it becomes important to complement on-axis field measurements with analysis and tuning of the higher-order field components. Here we describe how the pulsed wire measurement technique can be effectively used to retrieve on- and off-axis magnetic field characteristics of the undulator. A simple two-dipole model is developed to guide the final adjustments to the permanent magnet positions along the array to tune the quadrupole and sextupole components of the field.https://journals.iucr.org/paper?S1600577524012463free-electron laserspulsed wiremagnetic measurementsundulator tuning
spellingShingle A. Fisher
J. Jin
P. Musumeci
Controlling beam trajectory and transport in a tapered helical undulator
Journal of Synchrotron Radiation
free-electron lasers
pulsed wire
magnetic measurements
undulator tuning
title Controlling beam trajectory and transport in a tapered helical undulator
title_full Controlling beam trajectory and transport in a tapered helical undulator
title_fullStr Controlling beam trajectory and transport in a tapered helical undulator
title_full_unstemmed Controlling beam trajectory and transport in a tapered helical undulator
title_short Controlling beam trajectory and transport in a tapered helical undulator
title_sort controlling beam trajectory and transport in a tapered helical undulator
topic free-electron lasers
pulsed wire
magnetic measurements
undulator tuning
url https://journals.iucr.org/paper?S1600577524012463
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AT jjin controllingbeamtrajectoryandtransportinataperedhelicalundulator
AT pmusumeci controllingbeamtrajectoryandtransportinataperedhelicalundulator