Results of AC loss tests on twisted and untwisted HTSC tape exposed to an external field

This paper presents the results of magnetic loss tests on twisted and untwi sted 37 multifilaments tapes exposed to an alternating field at power frequ encies. The losses are measured using calorimetric methods, which are capab le of measuring losses in short tapes with the accuracy of several microwat ts per centimeter of tape, Tile losses of the tape due to the longitudinal field of the untwisted tape agree well with theoretical calculations. The m easurement results on the twisted filament tape, with 50-mm twist pitch, sh ow that the losses are slightly lower than that in the untwisted tape. This is due to the reduction of the coupling losses between the filaments in th e tape. It is also shown that in the presence of normal fields, the losses are about one order higher than for longitudinal fields because of the anis otropic properties of the superconducting parts and because of tile existen ce of eddy current loss in the silver sheath.