Safety and protection of 8T NbTi gyrotron magnet in persistent mode

Journal Article · Wed Sep 01 00:00:00 EDT 1993 · IEEE Transactions on Magnetics (Institute of Electrical and Electronics Engineers); (United States)

DOI:https://doi.org/10.1109/20.231627· OSTI ID:5910468

Usak, P; Kokavec, J; Chovanec, F; Krempasky, L; Gregor, B ^[1]

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1. Slovak Academy of Sciences, Bratislava (Slovenia)

Successful series of 5T cryomagnetic systems for additional high frequency plasma heating in Tokamaks T10 and T15, produced in Czechoslovakia during the last decade with the authors participation in magnet design and testing encouraged them to continue in further development of gyrotron magnets for further generation with operational field B[sub 0] = 8T. Approximately of the size and dimensions as was the case of previous 5T series, the 8T gyrotron magnet was designed as a part of preliminary work with preparations for ITER project. To achieve high mechanical stability of the superconducting winding, numerical stress-strain analyzes of winding structure and appropriate technology of epoxy impregnation were applied. To improve winding mechanical stability, initially round [phi]1 mm varnish insulated conductor was flattened to race track'' cross section (1.25 [times] 0.75 mm[sup 2] for inner section, respectively, 1.31 [times] 0.65 mm[sup 2] for the rest of magnet). Stainless steel road ([phi]1mm) of the bandage was flattened in the same way too (up to 1.14 [times] 0.77 mm[sup 2]). Danger of creating a hot spot region has been limited by radial magnet sectioning and sections shunting by low ohmic shunts. Superconducting switch was protected by couple of antiparallel silicon diodes mounted between magnet flanges in parallel to it. High threshold voltages of diodes at 4.2K allow to run up system with relatively high speed without any limitation on sign of magnet field polarity.

• OSTI ID: 5910468
• Journal Information: IEEE Transactions on Magnetics (Institute of Electrical and Electronics Engineers); (United States), Vol. 29:5; ISSN 0018-9464
• Country of Publication: United States
• Language: English

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