ON MODULAR STELLARATOR REACTOR COILS
Modular twisted coils are discussed which produce magnetic fields of the advanced Stellarator Wendelstein VII-AS type. For reactor dimensions (ASR): major radius R-o 25.5 m, plasma radius a 1.6 m, axis field B-o 5.3 T, coil radius r-c 5.2 m, distance d 1.8 m between coils and first wall, maximum field B-m 8.7 T and NbTi coils. Similar coils with smaller dimensions and larger fields are suitable for a burner experiment (ASB): R-o 15 m, a 0.9 m, B-o 7 T, r-c 3.2 m, d 1.2 m, B-m 10.3 to 12.6 T for 18, 9 or 6 coils/field period. Reducing the number coils/FP increases the magnetic ripple and B-m/B-o. B-m is determined by the material limit of the supraconductor. For a low number of coils/FP the shear becomes negative and the magnetic well flattens. Computation of force densities within the coils of ASR and ASB yield local maximum values of about 80 and 180 MN/m**3, at the coils with largest toroidal excursions. Supporting the coils (outer ring, lateral support elements, elastic paddings towards coil and outer rigid boundaries), results in local peak values for the von Mises stress of about 80 MPa and ASR and 130 MPa for ASB at radial inside of the coils with largest ellipticities (radial deflections 1.1 and 1.5 mm, respectively). A system of mutual coil support is being developed. Twisted coils in helical arrangement provide a reactor sized Heliac system. Local maximum fields and force densities are slightly larger than in ASR with same values of R-o, a and B-o.
Bibliographic Reference: 5TH INTERNATIONAL WORKSHOP ON STELLARATORS, SCHLOSS RINGBERG, BAVARIA (GERMANY), SEPT. 24-28, 1984 VOL. II, PP. 763-775, EUR 9618 EN (1985) FS, VOL. I AND VOL. II, 787 P., BFR 3500 (BOTH VOLUMES), EUROFFICE, LUXEMBOURG, POB 1003
Record Number: 1989124116000 / Last updated on: 1987-01-01
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