Resistive magnet technology for hybrid inserts

Abstract

The world’s highest-field dc magnets have, for roughly the past thirty years, consisted of resistive-superconducting hybrid magnets. These magnets use superconducting technology for the outer coils, where the magnetic field is moderate, and resistive-magnet technology for the inner coils, where the field is highest. In such a configuration, higher fields are attained than is possible with purely superconducting magnet technology, and lower lifetime (capital and operating) costs are attained than with a purely resistive magnet. The resistive coils of these magnets represent the pinnacle of high-field resistive-magnet technology and have been the focus of much of the resistive magnet technology development over the past thirty years. The evolution of high-field resistive magnet technology is presented, focusing on the development of hybrid inserts.

NMR spectroscopy up to 35.2 T using a series-connected hybrid magnet

“…The most common way of constructing these magnets uses high strength copper-alloy sheet metal, which is stamped into slit disks with hundreds of elongated cooling holes in a staggered grid (Florida-Bitter magnet design, Fig. 1b) [8]. Insulators of the same geometry are made and conductors and insulators are stacked in a helical manner to generate a coil.…”

Fusion nuclear science facilities and pilot plants based on the spherical tokamak

“…It is not expected that β = 8 N equilibria can be stably accessed in ST-FNSF, but this high value of β N is useful for equilibrium scoping and PF coil specification. Figure 16(a) shows that the aspect ratio A depends primarily on l i , and A decreases with increasing l i as the inboard gap shrinks with a more peaked For the PF coils considered for ST-FNSF, thermalhydraulic analysis finds the estimated winding-pack current density limits for multi-turn water-cooled copper coils using MgO insulation and stainless steel jacketing is 4-10 MA m −2 [137,138], while Bitter plate magnets have been operated at very high current densities up to 400 MA m −2 [139] in environments where radiation resistance is not an issue. Incorporating a ceramic radiation-resistant insulator may degrade this current density value somewhat, and research will be needed to verify that radiation will not induce arcing through the magnet cooling water [140].…”

Hybrid Magnet Design Consisting of a 20 T Superconducting Outsert and a 15 MW Resistive Insert

“…In recent years, the large-scale facilities such as the 32 MW-45 T National High Magnetic Field Laboratory in the United States [1] have made great progress in construction. In the United States, the electric power for water-cooled resistive magnets is now strengthened from 32 to 56 MW, and in Europe, the high-magnetic-field generation of 42-45 T is also aimed by the power supply of 20-24 MW in France [2] and in the Netherlands [3].…”