TY - JOUR

T1 - Polarization control of a free-electron laser oscillator using helical undulators of opposite helicities

AU - Yan, Jun

AU - Hao, Hao

AU - Huang, Senlin

AU - Li, Jingyi

AU - Litvinenko, Vladimir N.

AU - Liu, Peifan

AU - Mikhailov, Stepan F.

AU - Popov, Victor G.

AU - Swift, Gary

AU - Vinokurov, Nikolay A.

AU - Wu, Ying K.

N1 - Publisher Copyright: © 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

PY - 2020/6/1

Y1 - 2020/6/1

N2 - Polarized photon beams provide a unique experimental tool for the study of various polarization-dependent physical processes. Here, we report the experimental demonstration of full polarization control of an oscillator free-electron laser (FEL) using helical undulators of opposite helicities. Using two helical undulator magnets of opposite helicities and a buncher magnet in between, we have generated a linearly polarized FEL beam with any desirable polarization direction. With the development of a high-precision FEL polarimeter, we are able to optimize the highly polarized FEL beams in visible wavelengths and measure the polarization with high accuracy, demonstrating linear polarization Plin>0.99 on the routine basis and with the maximum polarization reaching Plin=0.998. In this paper, we describe the FEL configuration, experimental setup, and related beam diagnostics, including the newly developed high-precision FEL polarimeter. We report our experimental approaches to generate, tune up, and characterize the polarization controllable FEL beams and share a new insight into how high-degree polarization is realized based upon our investigation of the temporal structure of the FEL beam. This FEL polarization control technique has been used successfully to generate a polarization controllable Compton γ-ray beam for nuclear physics experiments.

AB - Polarized photon beams provide a unique experimental tool for the study of various polarization-dependent physical processes. Here, we report the experimental demonstration of full polarization control of an oscillator free-electron laser (FEL) using helical undulators of opposite helicities. Using two helical undulator magnets of opposite helicities and a buncher magnet in between, we have generated a linearly polarized FEL beam with any desirable polarization direction. With the development of a high-precision FEL polarimeter, we are able to optimize the highly polarized FEL beams in visible wavelengths and measure the polarization with high accuracy, demonstrating linear polarization Plin>0.99 on the routine basis and with the maximum polarization reaching Plin=0.998. In this paper, we describe the FEL configuration, experimental setup, and related beam diagnostics, including the newly developed high-precision FEL polarimeter. We report our experimental approaches to generate, tune up, and characterize the polarization controllable FEL beams and share a new insight into how high-degree polarization is realized based upon our investigation of the temporal structure of the FEL beam. This FEL polarization control technique has been used successfully to generate a polarization controllable Compton γ-ray beam for nuclear physics experiments.

KW - OPTICAL COHERENCE TOMOGRAPHY

KW - SYNCHROTRON-RADIATION

KW - SUM-RULE

KW - DICHROISM

KW - NUCLEON

KW - OPERATION

UR - http://www.scopus.com/inward/record.url?scp=85087712042&partnerID=8YFLogxK

U2 - 10.1103/PhysRevAccelBeams.23.060702

DO - 10.1103/PhysRevAccelBeams.23.060702

M3 - Article

AN - SCOPUS:85087712042

VL - 23

JO - Physical Review Accelerators and Beams

JF - Physical Review Accelerators and Beams

SN - 2469-9888

IS - 6

M1 - 060702

ER -