Microwave radar for non-destructive express testing of electrical properties of semiconductor materials which consists of pulsed magnet, transmitting and receiving antennas, high frequency generator, pulsed modulator and digital oscilloscope is described. In semiconductor specimen placed in pulsed magnetic field a magnetoplasmic wave is excited and propagated through the specimen. Delay time and attenuation of transmitted and reference signals are measured to find a value of concentration and mobility of free charge carriers in semiconductors. Experimental data of testing of InSb, n-InSb specimens are presented and acceptable for express testing correspondence of results was achieved.
The optimization of pulsed power inductors' geometry is a difficult multi-dimensional task. On the one hand, an inductor could be destroyed because of the Joule overheating, on the other hand, it might be damaged by the Lorentz forces acting in its windings. The magnetic field pulse up to 50 T is the target while fields of this magnitude are the interest in many scientific applications. All factors mentioned are directly dependent on inductor's geometry, i.e. on the number of winding layers and windings per layer. Therefore, a detailed analysis of thermodynamic, electromagnetic and mechanical processes is inevitable and was carried out for different geometrical inductor configurations to reach the goal: a non-destructive inductor that can meet required magnetic field parameters. Direct calculation methods were used to create universal algorithms in MATLAB environment. The zone of inductor geometries, where stresses do not exceed the yield strength of materials, inductor is not overheated and generated magnetic field magnitude is in acceptable range, is given as a result which enables to manufacture new prototypes saving additional costs and time.
It is demonstrated that polycrystalline La_{0.33}Ca_{0.67}MnO_3 thin film sensors can be used to measure pulsed strong magnetic fields with microsecond duration rise and decay times. The response characteristics of these sensors were investigated using 0.7-1.0 ms duration bell-shaped magnetic field pulses of 10-20 T amplitudes and by using special waveform magnetic field pulses with amplitudes of 40 T and decay times of 50μs. The response of these magnetic field sensors was compared with those of conventional loop sensors and Faraday rotation sensors using Bi_{12}SiO_{20} single crystals as a known standard.
The destructive laboratory device, generating half-period sinus-shaped magnetic field pulses of 0.15-2 ms duration is investigated numerically. The coil was placed into a steel reinforcement cylinder to resist magnetic forces, while influence of thickness of the reinforcement cylinder is considered in detail. The time-dependent non-linear magneto-mechanical model and the finite element software ANSYS are employed. On the basis of the mechanical analysis, reasonable explanation of the destruction nature is provided. The numerically obtained operation threshold value was in good agreement with experimental measurements.
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