A new method of surface resistance measurement with a niobium triaxial cavity working at 2 K
作者:
Changnian Liang,
Larry Phillips,
Ronald Sundelin,
期刊:
Review of Scientific Instruments
(AIP Available online 1993)
卷期:
Volume 64,
issue 7
页码: 1937-1940
ISSN:0034-6748
年代: 1993
DOI:10.1063/1.1143979
出版商: AIP
数据来源: AIP
摘要:
A 1.5‐GHz superconducting niobium triaxial cavity has been fabricated to study residual surface resistance of superconducting materials at 2 K. Unlike many other structures where the entire test samples have to be placed in strong magnetic field locations, we have the edge of a 25.4 mm or larger diameter sample outside of the strong field region, a procedure which will greatly reduce edge effects and image current losses between the thin film and substrate. A calorimetric method is used to measure the sample losses, and is designed to resolve a 10‐&mgr;K temperature change using 16 carbon resistor sensors. A detection limit of 0.05‐&mgr;W power dissipation has been determined with a calibration heater, which corresponds to a surface resistance of 0.02 n&OHgr; at a maximum cavity magnetic field of 250 G. Initial cavity testing was performed in a magnetically unshielded cryostat, yielding a 2.2‐&mgr;&OHgr; residual resistance which was measured by both the rf measurement and the calorimetric measurement.
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