Design of High Field Magnet Coils for Long Pulses

Abstract

Magnet coils are investigated which can produce magnetic fields of 15–40 MA/m (200–500 kOe) during working times of the order of 0.1 sec. These fields are suited for measurements in highly conducting materials. The coils are precooled to 20°K or 77°K and the Joule heat is not removed during the pulse. In Sec. I the thermal limitations of this method are reviewed. Plots are given for the optimum dimensions and current densities for coils producing a specified field during a specified time, minimizing the necessary power supply. Details of a magnet constructed along these lines are given. The maximum field produced by this coil, 16 MA/m (200 kOe) during 0.3 sec, however, proved to be determined by mechanical instabilities. These problems are reviewed in Sec. II. Calculations of the Lorentz force and the internal stresses resulting from it were carried out taking the elastic and plastic properties of copper and insulation into account. It is shown theoretically that a magnet stable to 35 MA/m (440 kOe) can be built from hard drawn copper if a reinforcing steel cylinder is used at a certain radius inside the coil.

Modeling and Multi-Objective Design Optimization of Quasi-Continuous High Magnetic Field Systems

“…Magnet shapes varies with different values of D out and H. With the same volume of conductors and current density j, B has a maximum value of B max when D out is 1.675 times of H. B max is calculated by Equation (10) [10].…”

“…According to [10], the average temperature T of the magnet during the pulse is calculated by Equation (11)…”

Beyond 60 T; a fruitful staircase to long-pulse 100 T fields

“…The calculations are based on the formulae describing the mechanical behaviour of coils [1] and optimisation of the magnets is based on paper [3].…”

“…Since 1969 the High Field Facility of the University of Amsterdam has a semicontinuous 40 T, 100 ms coil in operation [1]. The installation will be upgraded in the next few years with a new 60 T, 100 ms coil.…”

“…The use of exact scaling laws allows us to stale up this magnet to a 85 T, approximately 50 ms coil w!th an inner bore of about 15 cm [1]. The next step woul d then be to design an insert to be placed in this magnet] capable of producing 15 T during 50 ms in an inner bore of 2.5 cm.…”