Applicability of the US-DPC to the ITER model poloidal coil

The US-Demonstration Poloidal Coil (US-DPC) is a 2-m-diameter, 30 kA, 8 MJ, forced-flow Nb₃Sn solenoid made with a cable-in-conduit conductor using an Incoloy 908 conduit. It is approximately one half the scale of the proposed ITER (International Thermonuclear Experimental Reactor) model coil, and its test results offer several implications for the model coil design. The US-DPC was leak tight; it performed very well in DC tests; and it performed well in AC tests, achieving approximately 70% of its ambitious design goal of 10 T/s to 10 T in a series-connection mode with the JAERI background field coils DPC-U1 and U2. In a single-coil mode, the US-DPC achieved stable ramps ranging from 0.5 T/s to 6.6 T (35 kA) to as high as 19 T/s to 4.0 T (21 kA). An unexpected barrier of field or current (or both) versus ramp rate was identified above 23 kA, which appears to be related to short-duration energy disturbances and the `limiting current´ of the conductor. The authors describe the design and fabrication of the coil and the applicability of the US-DPC experience and test results to the ITER model poloidal coil