抄録
Recent results and encountered difficulties in the development of low loss fine filament composite superconductor are presented. The design criteria of superconductors for power frequency applications are discussed from the viewpoint of thermal properties, a.c. losses and the proximity effect and the critical elements to be satisfied by the a.c. conductors were clarified. The present state of the R & D of NbTi and continuous filament Nb3Sn composites is overviewed and special emphasis is placed on the identification of the problems of conductor fabrication and electromagnetic properties peculiar to ultrafine filament composites. The design parameters of ideal conductors are given in order to show the ultimate target.
