The Precise Measurement Of The Inductance And Resistance Of The Pulsed Magnet

The high magnetic field is produced by discharging from the pulsed power supply tothe pulsed magnet.The reliability and stability of the magnet will affect the effectiveoperation of the whole device of the pulsed magnetic field. The stress of the magnet maycause deformation of itself by discharging so many times. What’s more, the temperature ofthe magnet will change substantially during the discharging and cooling process. Thedegree of deformation and temperature rising is the sign of the stability of the magnet state.The deformation will cause the change of the inductance and the temperature rising willcause the change of the resistance. So the precise measurement of inductance and resistanceof the magnet can reflect the stability of the magnet and guarantee the safe operatingconditions of pulsed field magnets.A measurement system based on the digital lock-in technique has been developed byresearching the impedance measurement technology. A non-inductive reference resistorwith high thermal stability is connected with the magnet in series; The Voltage sourcecomposed by the DDS and power amplifier will be the power supply of the measurementcircuit; The voltages across the reference resistor and the magnet are used as referencesignal and measurement signal respectively; these are sampled synchronously by the ADconverter and processed with a digital lock-in amplifier algorithm. The inductance andresistance of the magnet can then be derived by computation. The IIR filter design and erroranalysis are also given. Besides, the means of communication is TCP/IP between theinstrument and the host computer.During the magnet measuring experiments, we got a lot of data of the inductance andresistance of the magnets by the instrument we designed. The data implied that accuracy ofthe inductance measurement is better than0.05%and it can meet the requirement ofmonitoring the magnets.