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

Jun Yan, Hao Hao, Senlin Huang, Jingyi Li, Vladimir N. Litvinenko, Peifan Liu, Stepan F. Mikhailov, Victor G. Popov, Gary Swift, Nikolay A. Vinokurov, Ying K. Wu

Результат исследования: Научные публикации в периодических изданияхстатьярецензирование


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.

Язык оригиналаанглийский
Номер статьи060702
Число страниц11
ЖурналPhysical Review Accelerators and Beams
Номер выпуска6
СостояниеОпубликовано - 1 июн 2020

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