Materials for 100 T Monocoil Magnets

Abstract

The development of improved conductors and reinforcement materials is instrumental for the achievement of ultra-high fields with monolithic magnets. They have the advantage that there is no coupling between the coils of the traditional two-coil systems, and that the magnet can be built much smaller, and it has longer pulse times. The fields that can be achieved are determined by the strain limitation of the conductor, and the strength and stiffness of the reinforcement. We have investigated the material requirements for this type of magnet to define the objectives for material development. It follows that future material development activities for reliable 100 T magnets should focus on conductors with the following specifications (all values are at 77 K): a) Ultimate conductor strength of 1.2 GPa, b) Conductivity of 500 percent IACS, c) 10 percent strain to failure, d) Fatigue strength of 1 GPa at about 5000 full load cycles from tensile stress at peak pulse to compressive stress after the pulse of about 0.6 GPa. It is equally important to improve the reinforcement materials. At the NHMFL, we use with great success a combination of Zylon fiber and MP35N superalloy. We have increased the isotropic strength of MP35N at 77 K to 2.6 GPa (modulus 240 GPa), and are working on further improvements.Index Terms-Fatigue strength, high-strength conductors, highstrength materials, monocoil pulse magnets, pulse magnets, reinforcement materials.

Rigid‐rod polymeric fibers

“…Achievable magnetic fields are determined by the strain limitation of the conductor, and the strength and stiffness of the reinforcement. Because of its high strength and stiffness, PBO fiber is used as reinforcement for producing high magnetic field at the National High Magnetic Field Laboratory in Tallahassee, FL, where efforts are currently underway to develop up to 100 Tesla pulse magnet 115. PBO fiber has also been tested for high temperature gas chromatography in fused silica capillary, showing improved results over the conventional capillary 116…”

Cryogenic properties of dispersion strengthened copper for high magnetic fields

“…It is therefore necessary to develop, characterize and understand the mechanical and microstructure of new and improved materials that have high strength and high electrical conductivity [2][3][4][5][6][7][8]. It is recognized that high tensile strength is desired to resist Lorentz forces inherent with high fields while high conductivity limits the Joule heating [9].…”

Strain Enhanced High Strength Cu–Ag–Zr Conductors

“…the conductivity of Cu) are observed. Even though the ultimate tensile strength and the conductivity coincide with the requirements for the conductor materials for pulsed high field magnets, the strain-to-failure value is still insufficient for the fabrication of next generation pulsed high field magnets with a flux density up to 100 T [10,[14][15][16].…”