Controlling beam trajectory and transport in a tapered helical undulator
In this paper we present a detailed discussion of the helical undulator system developed for high extraction efficiency experiments in the tapered-enhanced stimulated superradiant amplification regime. The design is based on permanent magnet technology and comprises two Halbach arrays orthogonally o...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
International Union of Crystallography
2025-03-01
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| Series: | Journal of Synchrotron Radiation |
| Subjects: | |
| Online Access: | https://journals.iucr.org/paper?S1600577524012463 |
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| Summary: | In this paper we present a detailed discussion of the helical undulator system developed for high extraction efficiency experiments in the tapered-enhanced stimulated superradiant amplification regime. The design is based on permanent magnet technology and comprises two Halbach arrays orthogonally oriented and shifted by 90° with respect to each other. When used in low energy beamlines for THz generation, the electron beam trajectory and transport are particularly sensitive to the undulator off-axis fields so that it becomes important to complement on-axis field measurements with analysis and tuning of the higher-order field components. Here we describe how the pulsed wire measurement technique can be effectively used to retrieve on- and off-axis magnetic field characteristics of the undulator. A simple two-dipole model is developed to guide the final adjustments to the permanent magnet positions along the array to tune the quadrupole and sextupole components of the field. |
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| ISSN: | 1600-5775 |