A pulse-type hysteresis loop tracer for rare earth based permanent magnets

A hysteresis loop tracer which is able to measure minor and major loops of Nd based high coercivity magnets with a single experiment is described. Oscillatory magnetic field 113.4 kOe of maximum amplitude, 71 Hz, 0.74 of amplitude damping ratio for measuring the M-H loop is generated by discharging a 5 mF capacitor charged with 600 V into the air solenoid (number of coil turns of 300, inner diameter of 14 mm, outer diameter of 36 mm, length of 32 mm) immersed into liquid nitrogen. The minor and major M-H loops of a Nd based magnet (6 mm dia. and 5 mm long) under the field is obtained with an electronic fluxmeter. The measurement is calibrated with a Ni rod with the same dimensions of the Nd magnet.