Winding, cooling and initial testing of a 10 H superconducting MgB₂coil for an induction heater

Abstract

A 10 H superconducting MgB 2 coil, suitable for an induction heating application, has been wound, cooled and initially tested. Eight kilometres of MgB 2 tape were first insulated and then wound into double pancake coils before being assembled into the complete coil. The process is described in detail, focusing on hands-on experience gained, especially regarding the different steps in the wet-winding technique used. The insulation, soldering, winding and cooling techniques applied proved practical for manufacturing of the large MgB 2 coil. The complete coil was cooled by conduction cooling to 8 K and tested with a current of 185 A.

Fabrication of a Scaled MgB2 Racetrack Demonstrator Pole for a 10-MW Direct-Drive Wind Turbine Generator

“…Also, for wet-winding it is possible to wind without dedicated electrical insulation, not before tested on MgB2 coils of this size. The absence of a Kapton insulation, as used in [13], results in a stiffer coil, avoiding the spongy effect [26], but leaving less soft material to take up any differences in thermal contraction between the materials or contractions of the epoxy during curing.…”

“…Large round MgB2 coils have been presented for MRI [11], [12] and induction heater [13] applications, in addition to several smaller test coils [14]- [18]. In the wind turbine generator, racetrack shaped coils are employed.…”

Design, Fabrication, and Testing of a Low AC-Loss Conduction-Cooled Cryostat for Magnetization Loss Measurement Apparatus

“…T HE discovery of superconductivity in MgB 2 [1] has enabled the possibility for cheap low-field magnets around 20 K [2], [3]. For applications using low-to medium-strength magnetic fields, it is possible that MgB 2 could become a costeffective alternative to NbTi, particularly if the availability of liquid helium is uncertain [4]- [6].…”

“…At 20-K temperature, several options, both pulse tube and Gifford-McMahon (GM) cycle, with cooling capacities from 1.5 W at 4.2 K to 22 W at 20 K, are commercially available [10], [11]. This allows the construction of dry cryogenic systems for superconducting magnets, e.g., for magnetic resonance imaging (MRI) [2], [12] and induction heating [3]. However, these dry systems often use large amounts of high thermal conductivity metals for interfacing the magnet to the cryocooler.…”

Hysteresis losses in MgB 2 superconductors exposed to combinations of low AC and high DC magnetic fields and transport currents

“…MgB 2 superconductors are, for their low cost compared to the high-temperature YBCO conductors, and higher operating temperature than the low-temperature Nb 3 Sn and NbTi superconductors, considered for several DC applications in the medium magnetic flux density range of 1-4 T. These applications include e.g., MRI magnets [1,2], magnets for induction heaters [3], and the field windings of wind power generators [4,5]. Under pure DC conditions the MgB 2 coils are practically loss-free (except for joints).…”