Nonlinear dynamics in a SPEAR wiggler

Safranek, J.; Limborg, C.; Terebilo, A.; Blomqvist, K. I.; Elleaume, P.; Nosochkov, Y.

doi:10.1103/physrevstab.5.010701

Cited by 33 publications

(20 citation statements)

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“…The integral along the actual trajectory of an electron beam, which is the so-called dynamic field integral, must be considered, particularly for a long period, strong field, and field gradient. This integral cannot be described with a straight line integral and has been shown to shrink a dynamic aperture in the case of a narrow wiggler pole [25]. An APPLE-II EPU has a narrow horizontal range of uniform field, producing strong dynamic multipole errors [26].…”

Section: Shimming Of Multipole Errormentioning

confidence: 98%

Development of an Algorithm for Magnet Sorting and Field Shimming for TPS Elliptically Polarized Undulators

Chung

Chang

et al. 2015

Synchrotron Radiation News

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A spatially periodic magnetic field is essential to cause an electron beam to wiggle and to emit electromagnetic radiation in a synchrotron (SR) source of radiation, and to provide fully coherent light in free electron lasers (FEL). To create this field, permanent magnets (PM) or electromagnets are patterned in a device commonly called an insertion device for SR and a radiator or modulator for FEL. In reality, magnet blocks or iron poles are not identical, in terms of geometry and magnetic properties, even with progressive manufacture. Compensatory methods are thus desired to recover the magnetic field and also to decrease the duration of construction. Magnet sorting is a pre-process that aims to eliminate the effect of manufacturing error. Before assembly of an insertion device, data of each component, especially the magnetic properties of each magnet block and the gap variation of mechanical structure, are organized to optimize the performance of the magnetic field. After that process, there is sometimes an optimization to shim the magnetic field. An effective algorithm of both processes is significant, particularly for a long undulator and an elliptically polarized undulator (EPU).An APPLE-II EPU comprises four PM arrays of Halbach type [1]. This device provides variable polarization of radiation via symmetric or antisymmetric movement of arrays [2]. In addition to a greater number of magnets than a normal planar undulator, an APPLE-II EPU suffers from magnetic forces of various kinds operating in varied phase modes; this condition becomes a challenge for mechanical design and field optimization. In total, 10 undulators will be installed in phase I at the Taiwan Photon Source (TPS). Among these, three are EPU; they will provide photon energy in a range from 0.25 or 0.45 to 2 keV for horizontal or vertical linear (HL/VL) mode and 0.3 to 1.5 keV for circularpolarization (CP) mode. Magnet sortingThere are two main requirements for an insertion device: to achieve the desired properties of radiation and to have no net effect on an electron beam. To realize the first objective, the magnetic field needs to have a purely periodic distribution. Radiation emitted from each pole has a correct correlation, resulting in a constructive interference. The phase error describes the deviation of the phase between a real device with field error and an ideal one at each pole [3,4]. The rms phase error, which has been shown to be well-correlated with the spectral intensity, must thus be minimized [5]. The first and second field integrals represent the exit angle and position of the electron beam, respectively. For the other objective, these field integrals in transverse directions must be minimized to effect a negligible multipole error. How to arrange thousands of magnet blocks to fulfill multiple requirements is the task of magnet sorting.Magnet sorting is a multi-objective problem of optimization. The best arrangement, which implies a global minimum of the configuration space, can be found if every possible combination is teste...

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Section: Shimming Of Multipole Errormentioning

confidence: 98%

Development of an Algorithm for Magnet Sorting and Field Shimming for TPS Elliptically Polarized Undulators

Chung

Chang

et al. 2015

Synchrotron Radiation News

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“…Tolerances for the dynamic field integral R B y ds have to be determined by performing tracking studies to specify the allowable range, where s denotes the trajectory of the particles. It is shown in [17] that it is not sufficient to consider R B y dz, where z follows the global coordinate of the overall beam direction. The good-field region is defined as the region where the relative change in magnetic flux density is less than 1 Â 10 À4 .…”

Section: Wiggler Magnet Designmentioning

confidence: 99%

“…Magic fingers magnetic shims can be used to compensate both for small errors of the first and the second field integrals and for small multipole errors due to mechanical errors in the wiggler magnets [17]. Additional steerers can be used for compensation of the field integrals.…”

Section: A Influence Of Field Errorsmentioning

confidence: 99%

Design and system integration of the superconducting wiggler magnets for the Compact Linear Collider damping rings

Schoerling

Antoniou

Bernhard

et al. 2012

Phys. Rev. ST Accel. Beams

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“…In some cases, it has been necessary to install additional magnets to compensate the more severe effects [1]. The effects of the wigglers in the damping rings for a future linear collider are of particular concern for three reasons.…”

Section: Introductionmentioning

confidence: 99%

Initial Studies of Nonlinear Dynamics in the KEK-ATF Wigglers

Wolski¹

2005

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The nonlinear fields in insertion devices can have a significant impact on the beam dynamics in storage rings. Various tools have been developed which allow the dynamical effects of a wiggler to be predicted, based on a detailed model of the magnetic field. The wigglers in the KEK-ATF have recently been commissioned, and provide an opportunity for benchmarking some of the analysis tools. We report on initial studies of the nonlinear effects of the KEK-ATF wigglers, based on studies of the change in betatron tunes with change in orbit through the wigglers, and compare the results with the predictions based on detailed field models.

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Nonlinear dynamics in a SPEAR wiggler

Cited by 33 publications

References 0 publications

Development of an Algorithm for Magnet Sorting and Field Shimming for TPS Elliptically Polarized Undulators

Development of an Algorithm for Magnet Sorting and Field Shimming for TPS Elliptically Polarized Undulators

Design and system integration of the superconducting wiggler magnets for the Compact Linear Collider damping rings

Initial Studies of Nonlinear Dynamics in the KEK-ATF Wigglers

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