A pulsed field magnetometer for the qualitiy control of permanent magnets

A pulsed field magnetometer (PFM) for industrial applications was developed. The system has a capacitor bank of 5mF for energy storage, which can be charged up to 3000V. The pulse magnet has a bore of 30mm (including the pickup coil), which is subdivided into two coils and produces a maximum field of 5T with pulse frequencies of 17.5 and 25Hz. The magnetisation is measured with a well balanced and temperature stabilised coaxial pickup system. The signal is integrated with a stable analogue integrator with selectable time constants. The signals are connected to a 14bit 5M sample/s two-channel ADC in a computer. For the data handling a C ++ -based computer program was written. The effects of eddy currents on the metallic samples are corrected by using the so-called f/2f method. Here two hysteresis measurements with two different time constants are used to measure the eddy current error. The function and reliability of the system is demonstrated by measuring the hysteresis of standard permanent magnets in the PFM and in a static system