The Nitrogen Boil-Off Method for Measuring AC Losses in HTS Coils

Author

Okamoto, H. ; Sumiyoshi, F. ; Miyoshi, K. ; Suzuki, Y.

Author_Institution

Kyushu Electr. Power Co, Fukuoka

Volume

16

Issue

2

fYear

2006

fDate

6/1/2006 12:00:00 AM

Firstpage

105

Lastpage

107

Abstract

We have developed a novel apparatus for applying a nitrogen boil-off method as a mean of making calorimetric measurements and allowing for simple measuring and evaluating of AC losses in HTS coils at liquid nitrogen temperature. With the ability to measure AC loss generated in superconductors directly, this method produces more reliable data than that obtained by general, electro-magnetic measurements. A sensitivity of about 0.1 W was achieved by improving sensitivity in measuring gas evaporation via the following three steps: (1) use of nonmetallic vessel, heat-insulated housing in which the sample is located; (2) optimization for sample vessel thickness and tube size; and (3) stabilization of evaporating gas emitted by the heater. It is widely expected that the proposed apparatus may be used for individual measurement of the magnetization loss and the transport current loss in HTS coils, as well as their total losses, in addition to the AC loss in irregularly shaped samples

Keywords

calorimetry; high-temperature superconductors; loss measurement; magnetisation; optimisation; superconducting coils; thermal insulation; AC loss measurement; Bi-2223; HTS coil; calorimetric measurement; electro-magnetic measurement; heat-insulated housing; heater; high temperature superconductor; liquid nitrogen temperature; magnetization loss; nitrogen boil-off method; nonmetallic vessel; optimization; sensitivity; transport current loss; AC generators; Current measurement; High temperature superconductors; Loss measurement; Nitrogen; Size measurement; Superconducting coils; Superconductivity; Temperature sensors; Thickness measurement; AC loss; Bi-2223; high temperature superconductor; magnetization loss; transport current loss;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/TASC.2005.869557

Filename

1642801