Performance of the merged APPLE-Knot undulator for soft x-ray beamline in medium energy ring

• Published in: Chinese physics B Vol. 32; no. 11; pp. 114102 - 276
• Main Authors: Cheng, Rui, Zhang, Fa-Yuan, Zha, He-Ming, Qiao, Shan
• Format: Journal Article
• Language: English
• Published: Chinese Physical Society and IOP Publishing Ltd 01.11.2023
• Subjects: APPLE-Knot undulator; soft x-ray; synchrotron radiation; APPLE-Knot undulator; synchrotron radiation; soft x-ray
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/acd924

APPLE-Knot undulator can effectively solve the on-axis heat load problem and is proven to perform well in VUV beamline and soft x-ray beamline in high energy storage ring. However, for soft x-ray beamline in a medium energy ring, whether the APPLE-Knot undulator excels the APPLE undulator is still a question. Here, a merged APPLE-Knot undulator is studied to generate soft x-ray in a medium energy ring. Its advantages and problems are discussed. Though the on-axis heat load of the APPLE-Knot undulator is lower in linear polarization modes compared to the APPLE undulator, its flux is lower. The APPLE-Knot undulator shows no advantage when only fundamental harmonic is needed. However, in circular polarization mode, the APPLE-Knot undulator shows the ability to cover a broader energy range which can remedy the notable shortcoming of the APPLE undulator.