Magnetic field decay in model SSC dipoles

Author

Gilbert, W.S. ; Althaus, R.F. ; Barale, P.J. ; Benjegerdes, R.W. ; Green, M.A. ; Green, M.I. ; Scanlan, R.M.

Author_Institution

Lawrence Berkeley Lab., California Univ., CA, USA

Volume

25

Issue

2

fYear

1989

fDate

3/1/1989 12:00:00 AM

Firstpage

1459

Lastpage

1462

Abstract

The authors have observed that some of the model SSC dipoles have long-time-constant decays of the magnetic field harmonics with amplitudes large enough to result in significant beam loss, if they are not corrected. The magnets were run at constant current at the SSC injection field level of 0.3 Tesla for one to three hours, and changes in the magnetic field were observed. One explanation for the observed field decay is time-dependent superconductor magnetization. Another explanation involves flux creep or flux flow. Data are presented on how the decay changes with previous flux history. Similar magnets with different Nb-Ti filament spacings and matrix materials have different long time field decay. A theoretical model using proximity coupling and flux creep as mechanisms for the observed field decay is discussed

Keywords

magnetic fields; magnetisation; niobium; storage rings; superconducting magnets; titanium; Nb-Ti filament spacings; SSC dipoles; flux creep; flux flow; magnetic field decay; magnetic field harmonics; proximity coupling; theoretical model; time-dependent superconductor magnetization; Creep; Delay effects; Laboratories; Magnetic field measurement; Magnetic fields; Magnetic materials; Magnetization; Superconducting magnets; Superconducting materials; Testing;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.92571

Filename

92571