Poloidal field electromagnetic engineering design for the TEXT upgrade

Summary Form only given, as follows. A major modification to the TEXT experiment is underway to extend the present program to include the study of diverted discharges and the H-mode confinement regime. The primary modification is to the poloidal coil system and consists of the addition of the divertor to the inner coil set of OH and VF windings. These windings are attached to a fiberglass cylinder located inside the TF coils on the inner major radius outside the vacuum vessel. The design of this inner coil structure is the critical feature of the upgrade. The design calls for a total of about 500 kiloampere-turns of current in a window of 480 cm/sup 2/ area, including insulation, cooling lines, coil feeds, attachment hardware, and fabrication and installation tolerances. The pulse length is 0.5 s, and the repetition rate is 2 min. This coil set will permit operation with a number of different plasma configurations. The overall design is a compromise between the requirement of maximum flexibility for plasma configuration, the technological limitations of materials and fabrication techniques, protection against failure by disruption, and the inevitable requirement of minimum cost and early completion schedules. Highlights of the design include the use of a pinned and clamped multiturn toroidal joint, the use of an alumina dispersed high strength copper alloy, and protection against the very high mechanical forces.<>