Design, Fabrication, and Test Results of Undulators Using<tex>$rm Nb_3rm Sn$</tex>Superconductor

Abstract

An R&D effort is underway at Lawrence Berkeley National Laboratory (LBNL) to develop the technology of Nb 3 Sn superconducting undulators (SCUs). Issues relating to the selection of the appropriate conductor are discussed. The design and fabrication of SCUs using Nb 3 Sn is presented. Two prototype devices have been designed and fabricated at LBNL. The first device concentrated on basic fabrication issues and on magnet protection, a key concern due to extremely high copper current densities during a quench. Test on the first prototype demonstrated that such devices can be passively protected in a scalable manner. The second device incorporated design improvements as well as trim coils that are designed to serve as the basic element of a future active phase error correction approach. Preliminary tests on the second device are presented. The trim coils were successfully tested at a variety of field levels. Two quench runs were performed, both occurring at 70% of short-sample J c . Stability issues associated with flux-jumps and possible epoxy cracking are discussed.

Correlation between strand stability and magnet performance

“…The stability of another strand (ORe 021) not reported here but presented in [23] shows that a wire with comparable Cu fraction and the same internal geometry (54 sub-elements distributed in three rings) but a smaller sub-element diameter is stable at low field. This shows the importance of decreasing the sub-element size in the type of conductor.…”

New developments in light source magnet design

“…Although preliminary concepts of active shimming have been tested [40,41], research is needed to develop a complete system compatible with user operation. The research and development of these devices has progressed to make them viable candidates for a variety of light source applications in the near future.…”

Development of a Cryogenic Calorimeter for Investigating Beam-Based Heat Load of Superconducting Undulators

“…Many synchrotron light sources start R&D of superconducting undulators for their storage rings (SR) or free electron laser. Beam-based heat load, cold magnetic measurement, and phase correction, are remaining issues to be resolved in the R&D of superconducting undulators [1]. Beam-based heat load are dynamic heat load which consists of image currents, synchrotron radiation from upstream bending magnets, E-cloud and RF effects [2].…”