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INSERTION DEVICES
Wigglers and Undulators
Presentation at JASS02 Seminar; Jordan, Oct. 19-28, 2002Herman Winick, SSRL/SLAC, Stanford University
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Wigglers & Undulators
(Undulator)
(Wiggler)
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Types of undulators
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SSRL 7 pole Electromagnet Wiggler - 1978
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Herman Winick on First SSRL Wiggler - 1978
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J. Spencer; Designer of 1st
Wiggler - 1978
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First Radiation from SSRL 7 pole Electromagnet Wiggler - 1979
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Display of 1st Wiggler at SSRL/SLAC
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SSRL 9-Pole Electromagnet Wiggler - 1980
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PHOTON ENERGY (KeV)
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PHOTON ENERGY (KeV)
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Daresbury SRS Superconducting Wiggler – Wavelength Shifter
Wide fan – Serves 7 experimental stations
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Klaus Halbach & Grandson ChrisLawrence Berkeley Lab
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Nikolay A. Vinokurov – Budker Institute, Novosibirsk, Russia
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LBL/SSRL 30 Period Permanent Magnet Undulator -1980
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Testing of First Undulator in SPEAR Tunnel - 1980
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First X-ray Undulator Spectrum; SSRL, 1980
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Permanent magnet undulator in SOR ring, Univ. of Tokyo ~1982
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Hybrid Design; K. Halbach & N. Vinokurov
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LBL-SSRL 54 Pole Permanent Magnet Hybrid Wiggler ~1985
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In-Vacuum Permanent Magnet Undulator in SPring-8 – H. Kitamura
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Undulator RadiationInterference effects in the radiation by an electron in a periodic field
Simple case to illustrate basis Physics
Weak field approximation & radiation on axis only
Electron takes longer than photon to go from 1-2 because electron travels at BC rather than C.
All the radiation occurs at this wavelength in the weak field approximation
If we take into account the extra distance traveled by the electron & also the angle of emission of the radiation (Θ) we get
Correlation between photon wavelength and emission angle
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Undulator RadiationMore realistic treatment: Take into account sinusoidal electron motion & off axis radiation
Electron flight time from 1 to 2:
Photon flight time from 1 to 2:
for constructive interference
1 or 2 Correlation between wavelength & viewing angle
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Steps in producing an insertion device; Al keeper + high permeability steel pole
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Adding magnetic material to each unit
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Assembling the individual units on a strongback
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LBL/SSRL 54 Pole Permanent Magnet Hybrid Wiggler ~1985
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Completed wiggler in support frame; ready for installation of the vacuum chamber
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Elliptical Undulator, Photon Factory, Japan H. Kitamura, S. Yamamoto
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End of this part of presentation