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Fabrication of a Short-Period Nb3Sn Superconducting Undulator
| Content Provider | Semantic Scholar |
|---|---|
| Author | Dietderich, D. R. |
| Copyright Year | 2008 |
| Abstract | IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 17, NO. 2, JUNE 2007 , pp 1243-1246. Fabrication of a Short-Period Nb 3 Sn Superconducting Undulator Daniel R. Dietderich, Arno Godeke, Soren O. Prestemon, Paul T. Pipersky , Nate L. Liggins, Hugh C. Higley, Steve Marks, and Ross D. Schlueter Abstract— Lawrence Berkeley National Laboratory develops high-field Nb 3 Sn magnets for HEP applications. In the past few years, this experience has been extended to the design and fabrication of undulator magnets. Some undulator applications require devices that can operate in the presence of a heat load from a beam. The use of Nb 3 Sn permits operation of a device at both a marginally higher temperature (5-8K) and a higher J c , compared to NbTi devices, without requiring a larger magnetic gap. A half-undulator device consisting of 6 periods (12 coil packs) of 14.5 mm period was designed, wound, reacted, potted and tested. It reached the short sample current limit of 717A in 4 quenches. The non-Cu J c of the strand was over 7,600 A/mm 2 and the Cu current density at quench was over 8,000 A/mm 2 . Magnetic field models show that if a complete device was fabricated with the same parameters one could obtain beam fields of 1.1 T and 1.6 T for pole gaps of 8 mm and 6 mm, respectively. Index Terms— Nb 3 Sn, Superconducting Undulator I. I NTRODUCTION Superconducting undulators (SCU’s) have the potential to enable a new generation of insertion devices with enhanced brightness and broadened energy range, representing significant improvements over existing radiation sources. The most promising (though aggressive) technology is based on Nb 3 Sn superconductors. An RD fax: 510-486- 5310; e-mail: drdietderich@lbl.gov) discussions with researchers from fellow light sources determined that image current heating may severely limit the performance of SCU’s [4]. The relatively high critical temperature (T c ) of Nb 3 Sn serves to mitigate the risks associated with uncertainties in the magnitude of the image current heating and in the performance of the magnets' cryogenic system without the need for an intermediate liner that adversely affects the magnetic gap, limiting ultimate performance. The R&D effort at LBNL has resulted in 3 prototype devices. The first device, with a 30 mm period, concentrated on basic fabrication details and magnet protection [5]. The second, a 14.5 mm device, included a number of design modifications/improvements based on experience from the first device [6]. A key feature of the second device was the implementation of NbTi trim coils to provide field perturbations for phase error correction on future devices. The trim coils achieved center-field perturbations of >1% at all field levels, as anticipated by models. The test demonstrated perturbation amplitude sufficient to provide a mechanism for active phase- error correction in future devices. The performance of the first two devices indicated that they were limited in some cases by magnetic instabilities and in others by mechanical disturbances. Two possible origins for Fig. 1. Main sections of the Nb 3 Sn SCU prototype and its components. The main coil is separated into its three sections: the yoke section in the middle of two independent stainless steel end block sections, which provide mechanical support and enable the Nb 3 Sn to NbTi splice. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://cloudfront.escholarship.org/dist/prd/content/qt8xv9v6f6/qt8xv9v6f6.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
