Computer-controlled 40 T magnetic field regulation

A description is given of the feedback system controlling the intensity of the magnetic field for the 40-T installation. A small computer generates the voltage that controls the next ignition moment for the 6-MW thyristor rectifier supplying power to the magnet coil. Part of the data is precalculated, using the known properties of the rectifier and coil, the latter as functions of coil temperature. The actual field is measured with a pick-up coil and an electronic integrator from which the output is digitized using a 16-bit analog-to-digital converter. The computer calculates the final adjustments of the controlling voltage from the deviations of the output of this ADC from the required value. After a settling time of about 20 ms, the maximum deviation of the actual field from the desired field is about 5 mT.