SU1386949A1 - Device for measuring induction amplitude of magnetic field pulses - Google Patents

Abstract

The invention relates to the field of measurement technology and can be used to measure the amplitude of induction of pulsed magnetic fields in solenoids with a small internal diameter. The device contains a source 14 of magnetized pulses, a solenoid 13, an exemplary resistor 12, an amplifier 8, a gate driver 7, a large-scale amplifier 10, a discriminator 6, a zero inductor .9, a sensor 1 made in the form of parallel cylindrical magnetic film 2 and compensating wire 3, forming a measuring bridge with resistors 4 and 5, registering the unit in the form of a meter 11 of the amplitude of the current supply pulses of the sensor 1. The device allows you to accurately determine the amplitude of the magnetic field pulse solenoids with a small internal diameter. 2 Il. Q e cl

Description

The device relates to a measurement technique and can be used to measure the amplitude of induction of pulsed magnetic fields in a solenoid with a small internal diameter,

The purpose of the invention is to expand the frequency range of measurements.

Figure 1 shows a block diagram of a device for monitoring the amplitude of induction of magnetic field pulses; figure 2 is a vector field diagram.

The device contains a sensor 1, made on parallel cylindrical magnetic film (CM11) 2 with a known bevel angle and a compensating wire 3, resistors 4 and 5, which form a measuring bridge connected in series with discriminator 2 and compensating with wire 3, sequentially connected discriminator 6, controlled by from the strobe pulse generator 7, the amplifier 8 and the null indicator 9, the amplifier 10 pulse current supply of the sensor, to the output of which a measuring bridge is connected, the input of the strobe pulse generator 7 and the pulse amplitude meter 11 The power supply of the sensor 1 and the input of the amplifier 10 are connected to the active resistance 12, inclusive in series with the solenoid 13, in which the measurement is made, and the source 14 of magnetizing pulses.

The device works as follows.

When a magnetic field H is generated in the solenoid due to a current pulse from source 14 flowing through the winding of coaxial 13, the magnetization vector of 1SW 2 deviates from the direction of the easy magnetization axis (EMA) in the direction of the axis of the CMP substrate 2, which coincides with the direction of the field Nu , and due to the presence of the bevel angle of the EMA, equal to oi, on the decay of the field impulse when its value becomes less than the anisotropy field ND of the film in the substrate

A CMP is induced by an EMF pulse causing an imbalance of the measuring bridge, and a signal is taken from the diagonal of the measuring bridge and is fed to the input of the discriminator 6. At the same time, the presence of a compensating wire 3 makes it possible to eliminate interference caused by induction.

Instantaneous value of a controlled field pulse in a solenoid

) associated with the instantaneous value of the current pulse in it I (t) by

H (t) KI (t),

(ABOUT

where K is the proportionality coefficient associated with the parameters of the solenoid.

As a result, the input of the amplifier 10 is supplied from active resistance 12 by a voltage pulse U (t), for which

u (t) to H, (t),

. (2)

where K is the ratio proportional to the altitude, depending on K and the magnitude of the resistance 12, Amplifier 10 with an adjustable gain factor increases the voltage pulses U (t) in power and from its output the current pulse of the sensor 1 flows through the measuring bridge and respectively, through the substrate CMP 2 and the compensating wire 3, and in accordance with formula (2)

I (t), (t).

(3)

where is the proportional factor, in which the gain factor of amplifier 10 is included as a factor. The flow of current supply pulse of sensor 1 through 1IMTI 2 substrate creates a pulse of additional magnetic field Hz (Fig. 2), the vector of which is perpendicular to the H field, and directed tangentially to PMP, and the instantaneous value is determined by

1pa

2 TGO

(four)

where D is the diameter of the substrate, and the coefficient 2 is due to the split of the supply current between LMP 2 and wire 3. The vector of the resultant field Ir, equal to the sum of the vectors of the fields H, and Nc, due to relations (3) and (4), is directed under the constant Angle / 3 (Fig. 2.) to the axis of the substrate by them, the value of which is determined by the ratio of the amplitudes of the pulses of the fields And, and Hz (H and Hz, corresponds to V

The amplitude of the current pulse of the sensor 1 is determined by the meter 1 1 by the magnitude of the amplitude, the voltage pulse B at the output of the amplifier 10 with known resistances of resistors 4 and 5 (equal to R) and resistances of the substrate 11MP 2 and the compensating wire 3 (equal to R ) by ratio

2U

pl

 (ft + Rn)

The voltage pulse U from the output of the amplifier 10 is supplied, moreover, 15 to the input of the strobe pulse generator 7, which has a response threshold

 Por -PRI

/ R Rn

I 2

 PAN 21GV-Nd. tgoi;

Hg is the anisotropy field of the CMP used;

oi - ut of the skew of its anisotropy axis.

As a result, the discriminator 6, controlled by pulses from the driver. 7, passes the signal from the measuring bridge to the amplifier 8 only at the moments of time when the magnitude of the field on the decay of the pulse of the measured field becomes less than the film anisotropy field, i.e. It transmits only the signal induced in the CMP substrate, which is amplified by the amplifier 8 and is applied to the null indicator 9.

By changing the current gain of the amplifier 10 pulses of the power supply current of sensor 1, there is no signal at the output of amplifier 8, which corresponds to a uniform decay of the magnetization vector of the DMP 2 in two opposite directions of the EA and, therefore, corresponds to the instant / 3 0.

For the amplitudes of the impulses of the fields H and H "at the time when in / 5, the relation is valid (figure 2).

 "BUT

iiA tgfc

(7)

Mr. Yu

15

20

25

l, Q

d. t in d 50

according to which the amplitude of induction Hj of the controlled field is determined, H is determined from relations (4) and (5).

The device allows you to accurately determine the amplitude of the induction of magnetic field pulses in solenoids with small internal diameter, used, for example, to control the parameters of cylindrical thin magnetic films, such as the anisotropy field, bevel angle, magnetostriction coefficient, etc.

Claims (1)

Invention Formula A device for measuring the amplitude of induction of pulses of a magnetic field containing serially connected source of magnetizing pulses, a solenoid and an exemplary resistor, a sensor located coaxially with the solenoid, an amplifier, a strobe pulse former, a large-scale amplifier whose input is connected to a sample resistor, and the output is connected to the input a strobe pulse former, a registering unit, characterized in that, in order to expand the frequency range of measurements, a discriminator and a null indicator are introduced into it, and a sensor It is complete in the form of successively connected and parallelly arranged cylindrical magnetic films and a compensating wire, included in the two arms of the measuring circuit, the other two arms of which are formed by balance resistances, the discriminator input being connected to the same diagonal of the bridge circuit, the other diagonal of which is connected to the output the scale amplifier and the input of the registering unit, the control input of the discriminator is connected to the output of the strobe pulse shaper, and the output through the amplifier is connected to zero the indicator. THEY  , - .x  - jrw HP