Options for the use of high temperature superconductor in tokamak fusion reactor designs

The environment close to the chamber of heavy ion inertial fusion energy reactors imposes severe constraints on magnets used for final focusing magnets. Space is at a premium, requiring close proximity of adjacent magnets, making magnet integration imperative. In addition, the high radiation flux imposes stringent shielding requirements. In this paper, the options for final focusing magnet topologies are described. Implications of using both high-temperature superconductors and conventional low-temperature superconductors are investigated. The use of high-temperature superconducting materials may offer an attractive, although speculative, opportunity for a fundamentally different approach to magnet construction, leading to either lower cost or reduced maintenance.

Design Requirements and Options for Final Focusing Superconducting Magnets of Heavy Ion Drivers

Superconducting options for final optics magnets for the Heavy Ion Driver in Inertial Fusion Energy

Apparatus for the investigation of low and high-T/sub c/ superconducting spirals has been designed and built. The device is capable of measuring the characteristic of superconducting spirals. The superconducting spirals are on a normally conducting substrate. The normally conducting substrate serves as a shunt between the superconducting turns, serving as a distributed quench protection resistor. Samples with both high and low electrical resistance substrates have been tested on this apparatus. Preliminary results of the tests of both high-T/sub c/ (Bi-Sr-Ca-Cu-O) and low-T/sub c/ (Nb-Ti) thick-film spirals have been investigated. Current distribution in films during quench has been studied experimentally. Generation of normal zone and hysteresis current-voltage characteristics have been discovered in high-T/sub c/ superconducting spirals on silver plate. It is shown that frequency of generation of normal zone depends at under certain conditions (transient current, magnetic field, temperature and resistivity of substrate). The results are being analyzed with models. >

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T. Holesinger

Papers

Electrical and thermal behavior of patterned superconducting disks