SU386357A1 - DEVICE FOR MEASUREMENT OF MAGNETIC PROPERTIES OF THIN FERROMAGNETIC SAMPLES - Google Patents

Description

one

Apparatus for measuring the magnetic properties of thin ferromagnetic samples are known, containing a variable magnetic field source, a test sample with a measuring winding connected through a preamplifier and an integrator to an oscilloscope vertical deflection channel, the horizontal deflection channel of which is connected to a variable magnetic source, and a camera for recording the curve hysteresis of the measured sample observed on the oscilloscope screen. However, when measuring small samples in such devices, the hysteresis curve, observed; on the oscilloscope screen, “trembles along the vertical axis with a frequency of low-frequency noise. Due to the afterglow, a wide blurred line is observed on the screen. As a result, a blurred image is also obtained on the film. This reduces the accuracy of determining the parameters of the magnetization reversal loop and limits the sensitivity of the device.

The proposed device is equipped with a single pulse generator, the input of which is connected to the camera shutter contacts, and the output through the diode is connected to an oscilloscope's brightness control electrode and connected in series by an amplifier, a full-wave rectifier, a delay line and a gating circuit. The amplifier input is connected to

the output of the preamplifier, the output of the gating circuit, with the oscilloscope brightness control electrode, and the other input of the gating circuit, with the output of the single pulse generator.

Such an embodiment of the device makes it possible to improve the accuracy of measuring the magnetic parameters of the samples when photographing the hysteresis loop of small-sized ones.

samples.

FIG. 1 is a diagram of the described device; in fig. 2 is a chart of signal temporal relationships.

The alternating magnetic field of the source

remagnetizes sample 2, with the result that a signal e is induced in the measuring winding 3 of the sample. d. magnetization reversal, which is amplified by amplifier 4 and integrated by integrator 5. From the integrator output, a signal proportional to the magnetic flux of sample 2, together with low-frequency noise, selected by the integrator, is fed to the Y input of the oscilloscope 6 (see Fig. 2, a). An oscilloscope provides a signal proportional to the source’s magnetic field. As a result, a hysteresis loop of sample 2 is observed on the oscilloscope screen. Then the beam brightness is output until the oscilloscope is completely darkened. At the moment the camera shutter 7 is pressed, the normally open contact 8 closes, which triggers a single-pulse generator 9, which supplies a pulse of a single luminance backlight to the Z input of the oscilloscope. The duration of the Ti pulse is slightly longer than the period T of the alternating magnetic field. When the circuit is disconnected, amplifier 10 - rectifier 11 - delay line 12 - gating circuit 13, the pulse amplitude at the brightness control electrode has a flat character (see Fig. 2.6). A single cycle of the hysteresis loop observed on the screen is recorded with the help of the camera 7 synchronously with the start of the illumination pulse (see Fig. 2, b). Since the frequency of magnetization reversal is large compared to the frequency of low frequency noise, the change in amplitude of low frequency sound during one cycle of nonremagnetization is negligible and the effect of low frequency sound on the measurement result is almost eliminated.

Using the camera circuit 7 - pin 8 - amplifier 10 - rectifier 11 provides additional illumination with a current proportional to the magnitude of the velocity of the beam moving along the Y axis. Since the observed value of Ooo Y is magnetic flux, the speed of the beam is proportional to the derivative of the magnetic flux of the sample or ed. with. remagnetization of the sample. Signal e. d. remagnetization is delayed in the adjustable delay line 12 for accurate phasing of the module relative to the recorded signal and is fed to the input of the / 3 gating circuit. A backlight pulse from generator 9 is also fed to the input of circuit 13. Thus, at the output of the gating circuit, a signal is received that is proportional to the module em. with. magnetization reversal only in that case.

if the circuit 13 is given a pulse of illumination. Then both signals from the circuit 13 and the generator 9 through the diode 14 are fed to the brightness control electrode (input Z of the oscilloscope). The shape of the beam current in this case is shown in FIG. 2, d. After several test shots with different ratios of the amplitudes of the backlight pulse and the signal proportional to the module ed. with. magnetization reversal, get a photo in which the width of the loop line is almost independent of the speed of the beam.

Subject invention

A device for measuring the magnetic properties of thin ferromagnetic samples, containing a variable magnetic field source, a test sample with a measuring winding connected through a preamplifier and integrator to an oscilloscope’s vertical deflection channel, whose horizontal deflection channel is connected to an alternating magnetic field source, and a camera, distinguished by that, in order to improve the accuracy of measuring the magnetic parameters of the samples when photographing the hysteresis loop, it A single pulse generator, whose input is connected to camera shutter contacts, and an output through a diode to an oscilloscope's brightness control electrode and serially connected amplifier, full-wave rectifier, delay line, and gating circuit, with the amplifier input connected to the preamplifier output, circuit output the gating is with the oscilloscope's brightness control electrode, and the other gating circuit input is with the output of a single pulse generator.

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