Speaker
Dr
Pavol Kováč
(Institute of Electrical Engineering of SAS)
Description
Thermally stabilized filamentary MgB2 wires with variable barriers (Nb, Ti, NbTi and C) and not magnetic sheaths (SS and GlidCop) have been made by in-situ PIT process. Critical current densities, Jc, and AC losses of wires and cables with different barriers and twist pitches have been measured and compared. AC loss of MgB2 wires exposed to the external AC magnetic field perpendicular to the wire axis was measured at temperatures between 18 K and 40 K by apparatus utilizing calibration free method. External AC magnetic field up to 70 mT in RMS and different frequencies from 2.3 Hz up to 1152 Hz were used. It was found that barrier material (its resistivity) has a direct effect to coupling AC looses. A strong coupling effect was found in non-twisted 30-filament wire with Ti barriers and also for cable made from 30-filament strands. The reduction of coupling losses with twist pitch was studied and related to the transport currents and an optimal twist pitch was found. The minimal AC losses and no transport current reduction were measured for cables made from single-core MgB2 strands.
Primary author
Dr
Pavol Kováč
(Institute of Electrical Engineering of SAS)
Co-authors
Mr
Imrich Hušek
(Institute of Electrical Engineering of SAS)
Dr
Jan Souc
(Institute of Electrical Engineering of SAS)
Mr
Ján Kováč
(Institute of Electrical Engineering of SAS)
Mr
Lubomir Kopera
(Institute of Electrical Engineering of SAS)
Mr
Tibor Melíšek
(Institute of Electrical Engineering of SAS)
