AC loss results of the Nb/sub 3/Sn Demo Poloidal Coil (DPC-EX)

AC losses in the DPC-EX, whose purpose is to demonstrate the applicability of Nb/sub 3/Sn conductor to poloidal coils for Tokamak fusion machines, were measured, and the results were analyzed. The coil was fabricated with a Nb/sub 3/Sn cable-in-conduit conductor and has a 1 m inner diameter. The AC loss was 9.4 kW for the pulse operation of a 0-17 kA-0 cycle with a ramp time of 1 s, corresponding to a 6.7-T maximum field and a 6.7-T/s pulse rate. It was 0.14% of the magnetic stored energy. The effective Nb/sub 3/Sn filament diameter was estimated as 32 mu m and the effective time constant of the coupling current within the strand was calculated as 2 ms on the assumption that coupling current between strands is negligible. The limitation of coil current due to AC losses is discussed.<
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