Effect of interturn spacing on AC loss of single layer Bi-2223/Ag coils

We studied effects of interturn spacing on AC losses and DC critical currents of single layer R&W coils wound from multifilamentary, untwisted Bi-2223/Ag tape. The losses at currents below the critical current increased proportional to i=(I/sub 0//I/sub c/)/sup n/, where n values were 3.6, 3.3, and 3 for coils with interturn gap 4 mm, 1 mm and 0.1 mm, respectively. At currents below I/sub c/ AC losses increased with decreasing interturn gap. We suppose that the observed loss increase is caused by the increase of magnetization losses, while self-field losses remain practically unchanged.