Orbit compensation for the time varying elliptically polarized wiggler (invited)

Singh, Om V.; Krinsky, S.; Ivanov, P.M.; Medvedko, E.

doi:10.1063/1.1147457

Cited by 9 publications

(4 citation statements)

References 5 publications

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“…This idea was realized in the elliptically polarizing wigglers at NSLS (Gluskin et al 1995) and APS (Gluskin 1998). The fast polarization switching of the NSLS device resulted in periodic orbit distortions which were successfully compensated with coils operated in a feedforward loop (Singh et al 1996a). The implementation of compensation schemes for a transparent operation is still a challenging task.…”

Section: Asymmetric and Elliptical Wigglersmentioning

confidence: 97%

“…In other designs, one field component is generated from permanent magnets to push the fields further, particularly for shorter-period devices, and the other field component is produced with coils to permit a fast switching (Chavanne et al 1998a;Rogalev et al 1999;Marteau et al 2011). Fast-switching devices may induce large eddy currents in the vacuum chamber which have to be compensated carefully for a transparent operation (Singh et al 1996b;Rogalev et al 1999). Usually, variably polarizing EMUs are mechanically rather simple devices.…”

Section: Elliptical and Helical Undulatorsmentioning

confidence: 99%

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Shaping Photon Beams with Undulators and Wigglers

Bahrdt¹

2014

Synchrotron Light Sources and Free-Electron Lasers

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Periodic magnetic structures, i.e., undulators and wigglers, have been used for nearly 40 years as sources of brilliant synchrotron radiation. Today, sophisticated undulator designs provide many degrees of freedom such as photon beam energy, variable polarization, and orbital angular momentum. Specific designs efficiently suppress higher orders or reduce the on-axis power density. All tuning parameters are required to be freely accessible by the users. Still, the majority of undulators is based on permanent magnets with a clear trend to short periods and in-vacuum and cryogenically cooled systems. Similar designs are used for storage rings and free electron lasers, though the field quality requirements are different. Today, the optimization of a specific experiment follows a global approach. This includes not only the undulator design itself but also local lattice modifications to cope with ambitious designs, elaborate tracking schemes to estimate the impact on the dynamic aperture, and last but not least radiation propagation tools which transport a realistic photon beam phase space to the sample. This chapter summarizes the theory of undulator radiation and reviews the technological realization of undulators and wigglers. Operational issues are discussed, as well.

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Section: Asymmetric and Elliptical Wigglersmentioning

confidence: 97%

Section: Elliptical and Helical Undulatorsmentioning

confidence: 99%

Shaping Photon Beams with Undulators and Wigglers

Bahrdt¹

2014

Synchrotron Light Sources and Free-Electron Lasers

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“…The alternation frequency of PMUs is limited to a few Hz 17 , because magnet arrays must be accelerated in the presence of strong magnetic forces. EMUs are limited in frequency by the coil selfinductance and the eddy currents induced into the vacuum chamber, where the eddy currents can be compensated with dedicated coils 18 . The helicity alternation rate of a SCAPE is restricted by the quench behavior of the wire.…”

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confidence: 99%

Flipping the helicity of X-rays from an undulator at unprecedented speed

et al. 2020

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X-ray circular dichroism (XMCD), one of the main tools to study magnetism, benefits enormously from the capability of a fast alterable helicity of circularly polarized X-ray photons. Here we present a method for boosting the alternating frequency between right-and left-handed photons to the MHz regime, more than three orders of magnitude faster than state-of-the-art technologies. The method is based on a twin elliptical undulator installed in an electron storage ring being operated in a novel mode where the electron optics is tuned close to a resonance with electrons captured in transverse resonance island buckets. Propagating through the twin undulator, electrons from different islands emit photons of the same wavelength but of opposite helicity. These two helicity components can be alternated as fast as 2 ns. In a proof-of-principle experiment at BESSY II, we demonstrate XMCD at the L 2 , 3 absorption edges of Ni with an 800 ns helicity flip.

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“…The very ®rst device of this type, which served as a prototype for the APS EMW, was designed, built and successfully tested jointly by the APS, NSLS and the Budker Institute of Nuclear Physics (BINP, Novosibirsk) at the NSLS X-ray ring Singh et al, 1996). The APS EMW was built jointly by the Figure 5 The harmonic structure of the undulator radiation at higher energies; harmonics as high as the 30th are clearly seen.…”

Section: Special Ids For Production Of Circularly Polarized X-raysmentioning

confidence: 99%

APS Insertion Devices: Recent Developments and Results

Gluskin

1998

J Synchrotron Radiat

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The Advanced Photon Source (APS) now has a total of 23 insertion devices (IDs). Over two-thirds of them are installed on the storage ring. The installed devices include 18, 27 and 55 mm-period undulators; an 85 mm-period wiggler; a 16 cm-period elliptical multipole wiggler; and many 33 mmperiod undulators. Most of the IDs occupy storage-ring straight sections equipped with 8 mm vertical-aperture vacuum chambers. All of the IDs were measured magnetically at the APS and, in most cases, underwent a ®nal magnetic tuning in order to minimize variation in the various integrals of the ®eld through the ID over the full gap range. Special shimming techniques to correct magnetic ®eld parameters in appropriate gap-dependent ways were developed and applied. Measurements of the closed-orbit distortion as a function of the ID gap variation have been completed, and results are in a good agreement with magnetic measurements. Spectral diagnostics of the ID radiation, including measurements of the absolute spectral¯ux, brilliance and polarization, show excellent agreement between calculated and measured results. Studies of the sensitivity of IDs to radiation exposure and measurements of the dose rate received by the IDs are in progress.

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Orbit compensation for the time varying elliptically polarized wiggler (invited)

Cited by 9 publications

References 5 publications

Shaping Photon Beams with Undulators and Wigglers

Shaping Photon Beams with Undulators and Wigglers

Flipping the helicity of X-rays from an undulator at unprecedented speed

APS Insertion Devices: Recent Developments and Results

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