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An Eddy-current based RRR measurement technique for SRF cavities

Sagar, P and Karunanithi, R and Hassan, HK and Akber, K and Girish, PS and Chandran, S and Lakshmi, EDA (2019) An Eddy-current based RRR measurement technique for SRF cavities. In: 27th International Cryogenics Engineering Conference and International Cryogenic Materials Conference 2018, ICEC-ICMC 2018, 3 - 7 September 2018, Oxford.

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Official URL: https://doi.org/10.1088/1757-899X/502/1/012154


Residual Resistivity Ratio (RRR) is an important parameter which is used to determine the purity and thermal conductivity of Niobium (Nb) utilized for fabrication of Superconducting Radio Frequency (SRF) cavities. The usual 4-wire electrical resistance measurement method is destructive in nature and produces a non-local (average) measurement of the electrical conductivity. The present work utilizes Printed Circuit Board (PCB) based planar inductor as sensing element. The impedance variation of the sensing element in the presence of a conducting metal (Nb), is used to determine the conductivity of the Nb target. A generalized equation for RRR is proposed in terms of parameters 'a' and 'b' associated with the sensing coil. The measurement method is experimentally verified by utilizing samples of Nb of known RRR values. The sensor parameters ('a' and 'b' ) are also established for cryogenic conditions. Errors in measurement, accuracy and repeatability of measurements down to 4.2 K are reported. © 2019 Published under licence by IOP Publishing Ltd.

Item Type: Conference Paper
Publication: IOP Conference Series: Materials Science and Engineering
Publisher: Institute of Physics Publishing
Additional Information: The copyright for this article belongs to the Authors.
Keywords: Cryogenics; Eddy current testing; Niobium; Printed circuit boards, Accuracy and repeatabilities; Electrical conductivity; Electrical resistance measurement; Generalized Equations; Measurement techniques; Printed circuit boards (PCB); Residual resistivity ratios; Superconducting radio frequency, Electric variables measurement
Department/Centre: Division of Physical & Mathematical Sciences > Centre for Cryogenic Technology
Date Deposited: 23 Oct 2022 10:01
Last Modified: 23 Oct 2022 10:01
URI: https://eprints.iisc.ac.in/id/eprint/77517

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