Pulsed magnetic field measurement system based on colossal magnetoresistance-B-scalar sensors for railgun investigation

Abstract

A high pulsed magnetic field measurement system based on the use of CMR-B-scalar sensors was developed for the investigations of the electrodynamic processes in electromagnetic launchers. The system consists of four independent modules (channels) which are controlled by a personal computer. Each channel is equipped with a CMR-B-scalar sensor connected to the measurement device-B-scalar meter. The system is able to measure the magnitude of pulsed magnetic fields from 0.3 T to 20 T in the range from DC up to 20 kHz independently of the magnetic field direction. The measurement equipment circuit is electrically separated from the ground and shielded against low and high frequency electromagnetic noise. The B-scalar meters can be operated in the presence of ambient pulsed magnetic fields with amplitudes up to 0.2 T and frequencies higher than 1 kHz. The recorded signals can be transmitted to a personal computer in a distance of 25 m by means of a fiber optic link. The system was tested using the electromagnetic railgun RAFIRA installed at the French-German Research Institute of Saint-Louis, France.

Velocity-induced current profiles inside the rails of an electric launcher

“…The software recalculates the measurement data of each connected sensor by applying the corresponding calibration data and displays the measurement signals. More detailed information about the CMR-B-scalar sensor system can be found in [18] and [21].…”

“…However, the data obtained suffered from electromagnetic interference. Therefore, the measurement system was considerably improved to gain a better signal quality [18]. This paper describes the continuation of the work presented in [16] and [17].…”

Accelerated ageing effects in nanostructured La0.83Sr0.17MnO3 films

“…Magnetic decoupling is thought to be the result of interfacial effects of grains and depends on grain boundary (GB) material which might be assumed as ferromagnetic regions with suppressed magnetic order [11] due to a high number of various defects, created during film deposition process. It was demonstrated [7] that long-term storage of thin polycrystalline films and post-annealing has also a significant influence on the demagnetization field of these films.…”

“…For this reason the temperature drift during operation of the CMR-B-scalar sensors is very important and has to be taken into consideration during design of such devices. This problem is solved by measurement of film's resistance in zero magnetic field just before the application of pulsed magnetic field which has to be measured [7]. In such case zero-field resistance of the film is a measure of ambient temperature while the resistance change in applied magnetic field is a measure of magnitude of this field.…”

Magnetoresistance and Resistance Relaxation of Nanostructured La-Ca-MnO Films in Pulsed Magnetic Fields

“…R ECENTLY, it was demonstrated that nanostructured (nanograined polycrystalline) La 1−x Sr x MnO 3 (LSMO) films which exhibit the colossal magnetoresistance effect (CMR) can be successfully used for the development of CMR-B-scalar sensors [1], [2]. These small-volume sensors allow for measurements of absolute magnitude of magnetic flux density B, in the time scale of milliseconds, during high magnetic field pulses.…”