Determination of the AC losses of Bi-2223 HTS coils at 77 K at power frequencies using a mass boil-off calorimetric technique

• Published in: IEEE transactions on applied superconductivity Vol. 13; no. 1; pp. 1 - 6
• Main Authors: Darmann, F., Shi Dou, Cook, C.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.03.2003; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; CALORIMETRY; CHEMICAL ANALYSIS; Coils; Copper; Electronics; Exact sciences and technology; Fluid flow; Fluid flow measurement; FREQUENCY; Frequency measurement; Glass; High temperature superconductors; LIQUID NITROGEN; Loss measurement; MAGNETIC FIELD; Magnetic field measurement; Magnetic fields; Mass flow; Measuring instruments; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; SOLENOIDS; Superconducting coils; Superconducting devices; SUPERCONDUCTIVITY; SUPERCONDUCTORS; Waveform; HTS tape; External field; Bismuth compound; Transport properties; System response; Loss measurement; boil off; Experimental study; Superconducting coils; Hysteresis loss; transport loss; Experimental result; Hz range; Measuring system; Calorimetry; Measurement method; AC losses; Magnetic field; Mass flow; High temperature superconductor; AC loss
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2003.809828

A mass boil-off measurement system has been used to accurately measure and characterize the ac loss of high-temperature superconductor (HTS) coils at frequencies between 50 and 200 Hz, and in applied ac fields of up to 0.04 T. The mass boil-off calorimeter incorporated a glass cryostat, a copper field coil, and two mass flow meters. The response of the gas flow to a step change in the applied magnetic field was found to have a time constant of about 600 s. Under suitable experimental conditions, it was possible to measure the ac losses of coils with an accuracy of /spl plusmn/0.3 W. The ac loss characteristics of an HTS pancake and two HTS solenoid coils are presented and the accuracy of mass flow calorimetry in liquid nitrogen is reported on.