MEASURING MULTIPOLE FIELD ERRORS IN MAGNET APERTURES OF LARGE ASPECT RATIO BY MEANS OF AN OSCILLATING WIRE ON ELLIPTIC TRAJECTORIES

P. Arpaia, C. Petrone, S. Russenschuck

Abstract

Errors in the transversal field of accelerator magnets are usually expressed in terms of the coefficients of a harmonic expansion on a circular trajectory in the magnet’s aperture.<BR />An elliptic trajectory more suited to apertures with large width-to-height ratios allows the field inside the domain to be reconstructed with a higher accuracy. Displacing an oscillating wire along an elliptical trajectory and acquiring the amplitude of the wire oscillation at each point yield a periodic signal to be expanded into the elliptic multipoles. The paper discusses the theoretical background, the practical implementation in the measurement system, and the accuracy achieved in the measurements of a quadrupole magnet.

Keywords

magnetic measurements, accelerator magnet, multipole field expansions

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IMEKO-WC-2012-TC4-O13.pdf

DOI

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IMEKO TC

TC4 - Measurement of Electrical Quantities

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