The Advanced Light Source elliptically polarizing undulator

Marks, S.; Cortopassi, Christopher; DeVries, J.; Hoyer, E.; Leinbach, Robert; Minamihara, Y.; Padmore, H. A.; Pipersky, P.; Plate, D.; Schlueter, R.; Young, A. T.

doi:10.1109/pac.1997.753161

Cited by 10 publications

(12 citation statements)

References 2 publications

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“…Helical undulators based on the APPLE II structure [3] have been built or are under construction in a number of facilities [4], [5], [6], [7] and at the ESRF. These devices are pure permanent magnet structures.…”

Section: Apple II End Field Structuresmentioning

confidence: 99%

End field structures for linear/helical insertion devices

Chavanne

Elleaume²,

Vaerenbergh³

1999

Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)

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The field integral tolerances required on third generation synchrotron sources are of the order of 10-20 Gcm in the whole gap range of an insertion device. This can be achieved without electromagnet correction by a proper magnetic design of the field termination. The paper describes several such end field terminations to be used for planar undulators. A new termination valid for an APPLE II undulator is presented which produces a field integral variation smaller than 20 Gcm for any useful setting of the magnetic gap and phase . It compares quite favorably with other known type of terminations.

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Section: Apple II End Field Structuresmentioning

confidence: 99%

End field structures for linear/helical insertion devices

Chavanne

Elleaume²,

Vaerenbergh³

1999

Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)

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“…The magnetic design of the EPU has been described previously (Marks et al, 1998) and is shown schematically in Fig. 1.…”

Section: Magnetic Structure Of the Epumentioning

confidence: 99%

Variable linear polarization from an X-ray undulator

Young

Arenholz

Marks

et al. 2002

J Synchrotron Radiat

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A new X-ray undulator has been designed and constructed which produces linearly polarized X-rays in which the plane of polarization can be oriented to a user selectable angle, from horizontal to vertical. Based on the Apple-II elliptically polarizing undulator (EPU), the undulator rotates the angle of the linear polarization by a simple longitudinal motion of the undulator magnets. Combined with the circular and elliptical polarization capabilities of the EPU operating in the standard mode, this new undulator produces soft X-ray radiation with versatile polarization control. This paper describes the magnetic structure of the device and presents an analysis of the magnetic ®eld with varying undulator parameters. The variable linear polarization capability is then exhibited by measuring the X-ray absorption spectrum of an oriented polytetra¯uoroethylene thin ®lm. This experiment, which measures the linear dichroism of the sample at two peaks near the C 1s absorption edge, demonstrates the continuous polarization rotation capabilities of the undulator.

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“…HREE elliptically polarized undulators (EPUs) have been installed at the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory [1]. All have a 50 mm period and are based upon the Apple-II design.…”

Section: Introductionmentioning

confidence: 99%

Shift Dependent Skew Quadrupole in Advanced Light Source Elliptically Polarizing Undulators, Cause and Corrections

Marks

Prestemon²,

Schlueter³

et al. 2006

IEEE Trans. Appl. Supercond.

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Abstract-Three elliptically polarizing undulators (EPU) are installed and operational at the Advanced Light Source (ALS); the most recent was installed in April '05. Operational experience has shown a variation in electron beam size which correlates with the EPU's magnetic quadrant shifts used to vary polarization. Storage ring electron dynamics studies pointed to the existence of a shift dependent skew quadrupole (SQ) component generated within the EPUs. Detailed magnetic and mechanical measurements demonstrated that the field errors were the result of systematic individual magnetic block displacements which vary with quadrant shift. This paper will discuss the results of electron dynamics studies, magnetic and mechanical measurements, design modifications planned for future EPUs to eliminate the SQ source, and the design and implementation of SQ compensation coils.Index Terms-Elliptically polarizing undulator, skew quadrupole, permanent magnets.

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The Advanced Light Source elliptically polarizing undulator

Cited by 10 publications

References 2 publications

End field structures for linear/helical insertion devices

End field structures for linear/helical insertion devices

Variable linear polarization from an X-ray undulator

Shift Dependent Skew Quadrupole in Advanced Light Source Elliptically Polarizing Undulators, Cause and Corrections

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