Forced flow He vapor cooled critical current testing facility for measurements of superconductors in a wide temperature and magnetic field range

Algirdas Baskys,Simon C Hopkins,Jakob Bader,Bartek A Glowacki

doi:10.1016/j.cryogenics.2016.07.003

Algirdas Baskys, Simon C Hopkins + Show 2 more

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https://doi.org/10.1016/j.cryogenics.2016.07.003

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Journal: Cryogenics	Publication Date: Jul 9, 2016
Citations: 4	License type: cc-by

Affiliation: University of Cambridge, University of Limerick

Abstract

As superconducting materials find their way into applications, there is increasing need to verify their performance at operating conditions. Testing of critical current with respect to temperature and magnetic field is of particular importance. However, testing facilities covering a range of temperatures and magnetic fields can be costly, especially when considering the cooling power required in the cryogenic system in the temperature range below 65K (inaccessible for LN2). Critical currents in excess of 500A are common for commercial samples, making the testing of such samples difficult in setups cooled via a cryocooler, moreover it often does not represent the actual cooling conditions that the sample will experience in service. This work reports the design and operation of a low-cost critical current testing facility, capable of testing samples in a temperature range of 10–65K, with magnetic field up to 1.6T and measuring critical currents up to 900A with variable cooling power.

Highlights

The current a given superconductor can carry depends on a multitude of variables including temperature, magnitude of the magnetic field and its direction
Low-cost system for critical current testing in a wide range of temperatures from 10 to 65 K and magnetic fields of up to 1.6 T, which in this case was limited by the electromagnet used
The critical current of the (RE)BCO coated conductor was measured at 1 T with the direction of the magnetic field parallel and perpendicular to the plane of the tape, and perpendicular to the current direction

Summary

Introduction

The current a given superconductor can carry depends on a multitude of variables including temperature, magnitude of the magnetic field and its direction. These data are important when designing and optimizing conductor materials for applications, and can serve as inputs for computer models [1,2] used to validate new designs of superconducting devices. Close contact with the cooling medium provides cooling for non-superconductive parts of the testing rig, i.e. current leads and sample contacts. Cryocoolers are increasingly popular, but their cooling power is still fairly modest, cool-down to testing temperature can take hours and a substantial capital investment is required, making them unfeasible for smaller institutions. Flow cryostat facilities tend to be bulky and require a magnet to be integrated into the system, increasing the cost [3,4]

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