24 August 2016

A better superconductor for Large Hadron Collider

Images of transverse cross-section of a reacted PIT wire with 7 rings of filaments and a typical filament shown in inset. Images of transverse cross-section of a reacted PIT wire with 7 rings of filaments and a typical filament shown in inset.

Scientists have discovered a way to significantly improve the performance of a decades-old superconductor, promising future applications for particle accelerators and research magnets.

First, some background

Niobium-tin (Nb3Sn) has been used as a high-field superconductor in magnet technology since the 1960s. It is still being developed for new applications, including a planned upgrade for the Large Hadron Collider at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland. This particular Nb3Sn wire is made by putting a powder made of tin into a tube of niobium. These filaments are then embedded in copper to form the final wire, which then undergoes a heat-treatment. The more current a wire can carry — a property known as its critical current density, or Jc — the better.

What is the finding?

When the wire is heat treated, the powder reacts with the tube and forms granular Nb3Sn. Small grains (with diameters of about 100 nm) carry current but large grains don’t, and larger grains typically make up about 25% of all the grains in a heat-treated wire.

Scientists discovered that varying the ratio of niobium to tin in the wire’s “recipe” prior to heat treatment resulted in significantly more small grains, which means a higher current density and a much better superconductor.

Why is this important?

High Jc Nb3Sn wires are essential for next-generation particle accelerators, high-field nuclear magnetic resonance magnets and future hybrid magnets at the MagLab.

Who did the research?

Christopher Segal1, Chiara Tarantini1, Zu Hawn Sung1, Peter J. Lee1, Bernd Sailer2, Manfred Thoener2, Klaus Schlenga2, Amalia Ballarino3, Luca Bottura3, Bernardo Bordini3, Christian Scheuerlein3, David C. Larbalestier1

1Applied Superconductivity Center, MagLab; 2Bruker EAS GmbH, Germany; 3CERN, Switzerland

Why did this research need the MagLab?

THE TOOLS THEY USED

This research was conducted in the Zeiss 1540 XB Crossbeam Scanning Electron Microscope at the Applied Superconductivity Center.

This study was made possible by the integrated sample preparation, metallographic imaging and electromagnetic analysis capabilities of the MagLab’s Applied Superconductivity Center (ASC). CERN has contracted for several years with the ASC to advance future particle accelerator technology using the center’s specialized analysis of both high-temperature and low-temperature superconducting materials.

Details for scientists

Funding

This research was funded by the following grants: G.S. Boebinger (NSF DMR-1157490); Christopher Segal (DOE/HEP-DESC0012083 & DE-FG02-07ER41451), (CERN - KE1920 and KN2713).
The PIT strand was supplied by the US LHC Accelerator Research Program (LARP), a BNL,FNAL, LBNL, and SLAC collaboration with CERN


For more information, contact David Larbalestier.

Details

  • Research Area: Superconductivity - Applied
  • Research Initiatives: Materials
  • Facility / Program: ASC
  • Year: 2016
Last modified on 7 December 2016