Seven research projects have been commenced under the Electric Research Council (ERC)'s underground transmission R & D program, in which Union Carbide Corporation (UCC) takes charge of a research project on a superconducting AC power cable system while General Electric Company is in charge of a project on a resistive-cryogenic cable system, and both are sponsored by the Edison Electric Institute and the Tennessee Valley Authority. The UCC Linde Division has made AC power loss measurements of pure niobium conductors and investigated a conceptual cable design and economic evaluation, and GE Co. has conducted dielectric characteristic tests at cryogenic temperature and made an evaluation of a cryogenic cable refrigerated by liquid hydrogen or nitrogen. Meanwhile, the Simplex Wire & Cable Company has made some tests of vacuum electrical insulations on a liquid nitrogen cooled cable at Waltz Mill testing facility funded by the ERC.
Measurements of heat fluxes to boiling helium from the surface of normal metal in the simulated cooling channel of superconducting pancake coil have been made. Critical heat fluxes Qn and Qf are presented as a function of gap width d for both horizontal and vertical channels. In the vertical channel Qn is independent of d down to 0.05mm unlike the other results of narrow channel experiments. Additive vapor experiments shows that the Qn for downward surface is greatly affected by extra vapor in the liquid.
A good cooling is essential to stabilize any superconducting wire. Immersion of superconductive coil in liquid helium has been a prevalent cooling method for a long time. As an alternative of cooling way, hollow supreconductor is introduced recently. In this cooling method, pressurized fluid phase helium is passed through passage of the hollow conductor. Stability problem of the hollow conductor is quite different from that of the conventional superconducting wire. This paper gives stability analyses on the hollow conductor and points out several parameters, affecting stability, which cannot be found in the conventional superconducting wire.