Undulator radiation brightness and coherence near the diffraction limit

The brightness and transverse coherence of undulator radiation in synchrotron light sources is investigated using the Wigner formulation in a full 4D treatment. New results are presented on the impact of energy spread on the brightness and coherence as a function of the emittance. In contrast to oth...

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Main Author: Richard P. Walker
Format: Article
Language:English
Published: American Physical Society 2019-05-01
Series:Physical Review Accelerators and Beams
Online Access:http://doi.org/10.1103/PhysRevAccelBeams.22.050704
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author Richard P. Walker
author_facet Richard P. Walker
author_sort Richard P. Walker
collection DOAJ
description The brightness and transverse coherence of undulator radiation in synchrotron light sources is investigated using the Wigner formulation in a full 4D treatment. New results are presented on the impact of energy spread on the brightness and coherence as a function of the emittance. In contrast to other work on this topic, it is found that as emittance decreases, the effect of energy spread increases, but as the diffraction limit is approached, the behavior of brightness and coherence diverge. The accuracy of the commonly used Gaussian approximation for brightness and coherence is also explored in detail, resulting in a new conclusion that the commonly used projected source sizes and divergences are not the appropriate quantities to use in the Gaussian approximation to obtain the most accurate results. New expressions are derived for the rms source size and divergence as a function of the energy spread for use in the Gaussian approximation.
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spelling doaj.art-11c2f3f9fb524454a236c87b1ba167572022-12-22T00:01:04ZengAmerican Physical SocietyPhysical Review Accelerators and Beams2469-98882019-05-0122505070410.1103/PhysRevAccelBeams.22.050704Undulator radiation brightness and coherence near the diffraction limitRichard P. WalkerThe brightness and transverse coherence of undulator radiation in synchrotron light sources is investigated using the Wigner formulation in a full 4D treatment. New results are presented on the impact of energy spread on the brightness and coherence as a function of the emittance. In contrast to other work on this topic, it is found that as emittance decreases, the effect of energy spread increases, but as the diffraction limit is approached, the behavior of brightness and coherence diverge. The accuracy of the commonly used Gaussian approximation for brightness and coherence is also explored in detail, resulting in a new conclusion that the commonly used projected source sizes and divergences are not the appropriate quantities to use in the Gaussian approximation to obtain the most accurate results. New expressions are derived for the rms source size and divergence as a function of the energy spread for use in the Gaussian approximation.http://doi.org/10.1103/PhysRevAccelBeams.22.050704
spellingShingle Richard P. Walker
Undulator radiation brightness and coherence near the diffraction limit
Physical Review Accelerators and Beams
title Undulator radiation brightness and coherence near the diffraction limit
title_full Undulator radiation brightness and coherence near the diffraction limit
title_fullStr Undulator radiation brightness and coherence near the diffraction limit
title_full_unstemmed Undulator radiation brightness and coherence near the diffraction limit
title_short Undulator radiation brightness and coherence near the diffraction limit
title_sort undulator radiation brightness and coherence near the diffraction limit
url http://doi.org/10.1103/PhysRevAccelBeams.22.050704
work_keys_str_mv AT richardpwalker undulatorradiationbrightnessandcoherencenearthediffractionlimit