An AC susceptometer for the characterization of large, bulk superconducting samples

TL;DR

This paper presents a low-cost, precise AC susceptometer designed for large superconducting samples, capable of rapid heating and detailed magnetic property measurements across a broad temperature range.

Contribution

The work introduces a novel, affordable susceptometer that enables accurate characterization of large bulk superconductors with high temperature resolution.

Findings

Successfully measured AC magnetic properties of RE-Ba-Cu-O superconductors

Achieved high heating rate with minimal temperature gradient

Provided detailed temperature dependence data near critical temperature

Abstract

The main purpose of this work was to design, develop and construct a simple, low-cost AC susceptometer to measure large, bulk superconducting samples (up to 32 mm in diameter) in the temperature range 78-120 K. The design incorporates a double heating system that enables a high heating rate (25 K/hour) while maintaining a small temperature gradient (< 0.2 K) across the sample. The apparatus can be calibrated precisely using a copper coil connected in series with the primary coil. The system has been used successfully to measure the temperature dependence of the AC magnetic properties of entire RE-Ba-Cu-O [(RE)BCO] bulk superconducting domains. A typical AC susceptibility measurement run from 78 K to 95 K takes about 2 hours, with excellent temperature resolution (temperature step ~ 4 mK) around the critical temperature, in particular.