Article

# Magnetic field calculations including the impact of persistent currents in superconducting filaments

CERN, Geneva

IEEE Transactions on Magnetics (Impact Factor: 1.42). 04/2002; DOI: 10.1109/20.996213 Source: IEEE Xplore

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**ABSTRACT:**Fast-ramping superconducting (SC) accelerator magnets are the subject of R&D efforts at various laboratories. The simulation of field quality in fast-ramping magnets requires modifications of magnet design tools such as the CERN field computation program ROXIE. In this paper we present the efforts towards dynamic 2-D simulations of fast-ramping SC magnets. Models for persistent currents, inter-strand coupling currents, inter-filament coupling currents, and for eddy-currents in conducting coil-wedges are described and validated.IEEE Transactions on Applied Superconductivity 07/2008; · 1.20 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**Brookhaven National Laboratory (BNL) has built a prototype superconducting dipole for the Facility for Antiproton and Ion Research (FAIR) at GSI that can be ramped at a high rate (1-4 T/s). To characterize the field quality at such high ramp rates, a measurement system consisting of 16 printed circuit windings was developed. In this system, the signals induced in all the windings as the magnet is ramped are analyzed to obtain the field harmonics. Initial measurements with this system suffered from somewhat poor resolution of the ADCs used for data acquisition. Also, only a few low order harmonics could be obtained with the 16 signals. These drawbacks have been addressed by replacing the ADCs with HP3458A voltmeters and by combining data taken with two different orientations of the probe. This has allowed us to measure very precisely (10 ppm of the dipole field) all the harmonics up to the 26-pole at ramp rates up to 4.3 T/s. The data analysis and results with this improved system are presented.IEEE Transactions on Applied Superconductivity 07/2008; · 1.20 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**The dipole magnets for the new heavy-ion synchrotron SIS-100, planned within the Facility for Anti-Proton and Ion Research (FAIR) at GSI, Darmstadt, Germany, have to be optimized under certain design requirements. At the intended high beam intensities, the field quality in the aperture is crucial. The geometry of the window-frame magnet featuring superconductive coils was already optimized with respect to the field quality in terms of higher-order multipoles using static 2D and 3D Finite Element (FE) simulations. During fast ramping up to 2 T, however, additional perturbations arise due to local saturation and due to eddy currents in both the yoke and the metallic beam pipe. These have already been investigated using transient 2D FE simulations. In order to further refine these results, a transient nonlinear 3D FE model, capturing the eddy-current effects at the end plates is used. The results are compared to those obtained by static simulations.IEEE Transactions on Applied Superconductivity 07/2009; · 1.20 Impact Factor

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