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[en] Damage to two large superconducting solenoids was caused by axial expansion forces and radial compression forces. These forces, which can be greater than and are of opposite sense to the classical Lorentz forces, are attributed to the diamagnetism of the composite superconductors. Some irregularities experienced in the operation of force cooled superconducting magnet systems appear to be readily understood by considering diamagnetic forces. It seems likely that several other previously unexplained occurrences in the operation of large superconducting magnets will also eventually be attributed to this effect. The mechanisms by which diamagnetic properties of superconducting strips produce repulsive forces on opposite edges of the strips are described. At the end pancake and innermost layer of a solenoid, these forces are seriously unbalanced and may override the Lorentz forces. The magnitude of these forces may be estimated and their effects may be minimized. It is suggested that the stress analysis of large superconducting magnets currently in operation or in design be reviewed to consider the relevance of diamagnetic forces to their safe operation

[en] Closely coupled, short-circuited shunt coils are proposed for quench protection of superconducting Maglev magnets which use high resistance, matrix composite conductors. It is shown that, by suitable design, the shunts can reduce induced ac losses and that the changing currents during magnet energization or vehicle lift off and landing can be tolerated. (author)

[en] Magnetic Barkhausen noise (MBN) and magnetic flux leakage (MFL) measurements are useful magnetic nondestructive techniques used for various applications. MBN measurements have been used here to study stress distributions around a racetrack-shaped defect made in the wall of a steel pipe. The study shows a stress concentration factor of ∼3 for a racetrack-shaped defect with 50% wall penetration. MFL signals from the same defect have also been studied under various circumferential hoop stresses. It is observed that the external stress can change the MFL signal by more than 40% and the effect of stress is maximum when the pipe wall flux density is ∼1.2 T

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[en] Measurements of the effects of stress on the initial magnetization curve of a sample of 1% Mn pipe line steel and on its reversible component are presented. Stress-induced changes in the reversible and irreversible magnetization components are shown. Examples of magnetization changes induced by tensile and compressive stress cycles of various amplitudes and at different fields are given. Magnetostriction measurements made on the same sample under various tensile and compressive stresses measured along anhysteretic and initial mangetization curves are included. A simple interpretation is suggested based on the assumption that stress changes the alignments of magnetic domain easy axes with respect to the strain

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[en] A superconducting flux pump power supply of the transformer--rectifier type is described. Load current commutation between gates is by transformer primary current control. A simple, inexpensive system of generating the required control waveforms is outlined. Results of load magnet charging tests to currents of 500 A are given and are consistent with calculated performance