A large conventional MHD magnet

A transverse-field, water-cooled electromagnet for magnetohydrodynamic (MHD) research has been designed, constructed, and successfully tested to a peak central magnetic field of 4.2 T. This paper consists of a brief review of the electromagnetic, mechanical, and thermal designs, and a comparison of test data with design values. The magnet is made up of 9 tonnes (20,000 lb) of hollow copper conductor wound into 8 double-layer pancake coils. A frame of 24 tonnes (53,000 lb) of low carbon steel acts as a low reluctance path for the magnetic flux, while providing support for the coils against the transverse electromagnetic forces. The magnet has been operated continuously at a power level of 4.7 MW, a voltage of 490 V, a current of 9.60 kA, and a copper current density of 1.52 kA/cm
²
(9.80 kA/ in
²
). At this level, a peak central magnetic field of 4.2 T is provided horizontally across a 0.267m (10.5 in) gap which is 0.368 m (14.5 in) high. The steel return frame is 1.422 m (56.0 in) long, while the overall length of the magnet is 2.5 m (98 in). The coils are cooled from a closed-loop demineralized water system which provides 109 liter/s (1730 gpm) at a pressure drop of 0.683 MPa (99 psi) across the magnet coils and manifolds.