A helical undulator was installed in the 0.75 GeV storage ring of the UVSOR facility of the Institute for Molecular Science. The undulator was designed to produce the fundamental of the circularly polarized undulator radiation in the energy range 2-43 eV, and the higher harmonics with elliptical polarization in the energy range up to 300 eV. Recently, the first spectrum from the undulator was observed. The performance of the undulator and the obtained spectrum are reported.
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http://dx.doi.org/10.1107/S0909049597013009 | DOI Listing |
J Synchrotron Radiat
July 2024
Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland.
This article presents a demonstration of the improved performance of an X-ray free-electron laser (FEL) using the optical klystron mechanism and helical undulator configuration, in comparison with the common planar undulator configuration without optical klystron. The demonstration was carried out at Athos, the soft X-ray beamline of SwissFEL. Athos has variable-polarization undulators, and small magnetic chicanes placed between every two undulators to fully exploit the optical klystron.
View Article and Find Full Text PDFJ Phys Condens Matter
July 2024
Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States of America.
In addition to spin angular momentum, light can carry orbital angular momentum. The orbital angular momentum degree of freedom in the extreme ultraviolet and x-ray regimes enables fundamental studies of light-matter interactions and new methods to study materials. Advances in x-ray optics, as well as undulator radiation and high harmonic generation techniques, lead to the creation of beams with non-trivial phase structure, such as a helical phase structure, creating new possibilities for the use of extreme ultraviolet and x-ray photons with orbital angular momentum in probing complex electronic structures in matter.
View Article and Find Full Text PDFChirality
January 2024
Department of Electronic and Electrical Engineering, Muroran Institute of Technology, Muroran, Japan.
Electrons in circular motion emit electromagnetic radiation and lose their energy and angular momentum, both of which are carried away by the radiation field. Electromagnetic radiation from such electrons is not only circularly polarized but also, in general, possessing helical phase structure, the former of which corresponds to spin angular momentum and the latter orbital angular momentum. Based on the classical electrodynamics, we show that the chiral topological property related to the orbital angular momentum arises from deformation of the electromagnetic field due to the relativistic effect.
View Article and Find Full Text PDFSci Rep
December 2023
Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan.
Young's double-slit interference experiments with undulator vortex radiation were conducted, focusing on photon-counting regime. To isolate the second harmonic radiation in the ultraviolet range emitted from the helical undulator and achieve successful counting measurements, an ultranarrow bandpass filter was utilized under an extremely low-current mode of the electron storage ring. It was observed that the photon spots on the detector, after passing through the double slits, appeared to be randomly distributed.
View Article and Find Full Text PDFIn this Letter, we propose a novel, to the best of our knowledge, technique to generate short-wavelength radiation carrying time-varying orbital angular momentum (OAM) by tailoring relativistic beams in free-electron lasers. To manipulate the temporal properties of OAM beams, two time-delayed seed lasers with different OAM values are used to interact with the electron beam in the undulator. With this method, high-harmonic electron beam microbunching with a time-varying helical distribution can be tailored to match the time-varying instantaneous helical phase structure of the x ray beams.
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