Measurement System for Short-Pulsed Magnetic Fields

Abstract

A measurement system based on the colossal magnetoresistance CMR-B-scalar sensor was developed for the measurement of short-duration high-amplitude magnetic fields. The system consists of a magnetic field sensor made from thin nanostructured manganite film with minimized memory effect, and a magnetic field recording module. The memory effect of the La1−xSrx(Mn1−yCoy)zO3 manganite films doped with different amounts of Co and Mn was investigated by measuring the magnetoresistance (MR) and resistance relaxation in pulsed magnetic fields up to 20 T in the temperature range of 80–365 K. It was found that for low-temperature applications, films doped with Co (LSMCO) are preferable due to the minimized magnetic memory effect at these temperatures, compared with LSMO films without Co. For applications at temperatures higher than room temperature, nanostructured manganite LSMO films with increased Mn content above the stoichiometric level have to be used. These films do not exhibit magnetic memory effects and have higher MR values. To avoid parasitic signal due to electromotive forces appearing in the transmission line of the sensor during measurement of short-pulsed magnetic fields, a bipolar-pulsed voltage supply for the sensor was used. For signal recording, a measurement module consisting of a pulsed voltage generator with a frequency up to 12.5 MHz, a 16-bit ADC with a sampling rate of 25 MHz, and a microprocessor was proposed. The circuit of the measurement module was shielded against low- and high-frequency electromagnetic noise, and the recorded signal was transmitted to a personal computer using a fiber optic link. The system was tested using magnetic field generators, generating magnetic fields with pulse durations ranging from 3 to 20 μs. The developed magnetic field measurement system can be used for the measurement of high-pulsed magnetic fields with pulse durations in the order of microseconds in different fields of science and industry.

Engineering of Advanced Materials for High Magnetic Field Sensing: A Review

“…Despite the fact that the resistance of manganite film, which is a basic element of the sensor, is dependent on ambient temperature, the CMR-B-scalar sensors can be successfully calibrated in advance in a wide range of temperatures (see Figure 13 b) and the data are stored in the software of the system what allows simultaneous conversion of the measured signal (voltage) to magnetic field values [ 10 ]. It should be noted that the operation temperature range of the sensors could be increased by using nanostructured manganite La 1 − x Sr x Mn y O 3 films with Mn excess ( y > 1) [ 11 , 94 ]. For films with y = 1.15, the largest MR values were obtained at T = 363 K in a magnetic field of 20 T [ 11 , 94 ].…”

“…It should be noted that the operation temperature range of the sensors could be increased by using nanostructured manganite La 1 − x Sr x Mn y O 3 films with Mn excess ( y > 1) [ 11 , 94 ]. For films with y = 1.15, the largest MR values were obtained at T = 363 K in a magnetic field of 20 T [ 11 , 94 ]. As mentioned before, Mn excess in manganite films increases the Curie temperature, which results also in increased low-field magnetoresistance at close to room temperatures.…”

“…However, magnetic sensors based on colossal magnetoresistance effect (CMR) are still at laboratory-scale development [ 7 , 8 ], despite the efforts to commercialize the CMR technologies [ 9 ]. Nevertheless, some CMR-based magnetic field sensors have already been developed up to 8th technological readiness level (TRL) for specific scientific applications in high-field measurements [ 10 , 11 ].…”

“…The experimental accuracy of the measurable quantities depends also on the accuracy of measured magnetic field values during the entire pulse of the magnetic field. Therefore, high temporal resolution (to obtain a sufficient number of data points during the pulse) and measurement accuracy of magnetic field magnitude become very important parameters for magnetic sensing techniques used in high-pulsed magnetic field systems [ 11 ].…”

“…During the magnetic pulse, a large d B /d t induces large pick-up noise in the wires of the sensor, and it becomes difficult to extract the relevant data during a single measurement [ 21 ]. From this point of view, the magnetoresistive materials, whose structures can be designed with only two electrodes, are preferable [ 10 , 11 ]. Therefore, the choice of materials and engineering of nanostructures as well as the development of various sensor technologies which can be quickly adopted from the laboratory scale to commercial production are of great importance.…”