Electrical insulation systems for the ITER Central Solenoid Model Coil

Insulation systems developed by Composite Technology Development, Inc., have been fabricated specifically for use in the US section of the International Thermonuclear Experimental Reactor (ITER) Central Solenoid (CS) Model Coil. The insulation system used in these fusion devices must be capable of withstanding significant mechanical loads at cryogenic temperatures and enduring high doses of radiation, all without compromising their electrical insulation properties. Two materials that have seen extensive use in the CS Model Coil are the CTD-112P tetrafunctional epoxy pre-preg system and the CTD-618 epoxy system. Fabrication methods for these materials were developed and implemented specifically for use on the model cell. The CTD-112P system has been successfully used as the primary turn insulation, and as such, has been tested extensively for its mechanical and electrical properties, before and after irradiation. The CTD-618, a room-temperature cure system, has been specified as the insulation system for repair of damaged turn insulation and also as the insulation for the noncritical areas of the tension links and terminations. The development of these materials and the method of application for each of these materials as they apply to the model coil are examined. Pertinent mechanical and electrical properties are also analyzed.