RU2455639C1 - Method of detecting breakage of ferromagnetic fibre in localised superstrong magnetic field - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: method employs a magnetic explosion generator to generate a magnetic field based on a coil of explosive wire. A centrally-symmetrically loaded ferromagnetic fibre made from ferromagnetic material, e.g., a thin wire made from rare-earth metals or compounds thereof, which is stretched by the load applied to it, is placed inside the coil.

EFFECT: possibility of detecting breakage of ferromagnetic material in superstrong spatially localised magnetic fields, particularly breakage of a loaded fibre made from ferromagnetic material lying in such a field.

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Description

The invention relates to the field of magnetism of ferromagnets and can be used to register structural changes in ferromaterial in a superstrong magnetic field.

It is known that ferromagnets are characterized by parameters of magnetic viscosity and magnetic susceptibility. The latter changes when the external magnetic field changes in accordance with the so-called Stoletov curve. In particular, in the absence of a magnetic field, the magnetic susceptibility χ is characterized by a certain value, much larger than unity, called the initial magnetic susceptibility χ _NACH . As the external magnetic field increases, the magnetic susceptibility increases, reaches a maximum χ ^∗ , and then decreases. The dependence of magnetic induction B on the intensity of the external magnetic field H acting in a ferromagnet is a known hysteresis curve and, in particular, has a paraprocess-saturation induction region in which the induction practically does not increase with increasing magnetic field strength, that is, the magnetization of the ferromagnet does not increase J = [χ (Н) +1] _∗ μо Н, where μ = χ (Н) +1 is the relative magnetic permeability of the ferromagnet. B = µo µ N, where µo = 1,256.10 ^-6 GN / m is the absolute magnetic permeability of the vacuum. Thus, the invariance of the magnetization J upon magnetic saturation of a ferromagnet means that the quantity [χ (Н) +1] _∗ Н≈const. With a significant increase in the magnetic field H, the magnetic susceptibility of the ferromagnet is χ (Н) → 0, since χ (Н) = (const / Н) -1, in particular, at Н = const. The value of the indicated constant is of the order of magnitude const≈ (2 ... 4) χ ^∗ H ^∗ , where H ^∗ is the value of the magnetic field strength at which the maximum value of the magnetic susceptibility χ ^{∗ is} reached. In other words, at H = (2 ... 4) χ ^∗ H ^{∗, a} ferromagnet becomes a paramagnet with a magnetic susceptibility close to zero and, accordingly, a destroyed domain structure characteristic of dia- and paramagnets [1-3].

Superstrong magnetic fields are created in various ways [4-10], one of which is the method of exploding single-turn wires. The generation of an ultrahigh magnetic field with a strength of 1 ME = 8.10 ⁷ A / m is accompanied by significant damage to the material of the coils and even their destruction, that is, magnetic systems become suitable only for single use. The simplest way to obtain an ultrahigh magnetic field is to discharge a battery of pulse capacitors through a single-turn solenoid. In this way, magnetic fields of up to 4 ME are obtained, i.e. more than 3.10 ⁸ A / m. A 4-ME field has an energy density comparable to the binding energy of an atom in solids (for metals it has a value of several eV / atom). In the zone of action of such a field, as a rule, complete destruction (turning into steam) of the material of the coil occurs. It is known that when ferromagnets are exposed to superstrong magnetic fields of this level, it affects the restructuring of atomic structures, leading to the appearance of new, unusual states of matter, including the possibility of their destruction.

The aim of the invention is to register the destruction of the ferromagnetic material in superstrong localized in the field of magnetic fields, in particular, the breakage of the loaded filament from a ferromagnetic substance placed in such a field.

This goal is achieved in the inventive method for detecting a rupture of a ferromagnetic filament in a localized superstrong magnetic field, based on the use of an explosive magnetic field generator based on a coil of an exploding wire, characterized in that a centrally symmetrically loaded ferromagnetic filament from a ferromagnetic material is introduced inside the coil of an exploding wire, for example , a thin wire of rare earth metals or their compounds, which is stretched by the load applied to it.

Achieving the objective of the invention is explained by structural changes in the atomic-molecular structure of strained ferromagnetic filaments of ferromagnetic material in an ultrastrong spatially localized magnetic field.

The method is illustrated by the device implementing it, shown in the figure.

This device contains the following elements and nodes:

1 - a thin metal thread from the studied ferromagnetic material, for example, from rare-earth metals (or their compounds), suspended vertically,

2 - weight-controlled load, for thread tension 1,

3 - a round coil of exploding wire, through the center of the cross section of which passes a thin metal thread 1,

4 - a piece of thick-walled glass tube to protect the filament 1 from the resulting blast wave,

5 - a battery of high voltage capacitors,

6 - high voltage arrester,

7 - source of high voltage DC

8 - resistor limiting the charge current of the battery of capacitors 5.

Consider the action of this device.

A capacitor bank 5 is charged from a high-voltage DC voltage source 7 through a resistor 8. When a predetermined charge voltage of the capacitor bank 5 is reached, an electric breakdown occurs in the high-voltage spark gap 6, and a powerful current pulse passing through a round turn of the exploding wire 3 forms in its central section an impulse of a superstrong magnetic field, which destroys the atomic-molecular structure of a thin metal filament 1 from a ferromagnetic substance, for example, from rare-earth metals llov or their compounds. In this section of the round turn, the thread 1 is broken, stretched by a weight-controlled load - suspended on the thread 1 by a weight 2 of a certain weight. Depending on the magneto-physical properties of the test ferromaterial of the yarn 1 at a given superstrong magnetic field at a given cross-section of the conductor of the yarn 1, it breaks off at different values of the weight of weight 2, which is the object of study. The change in the magnitude of the magnetic field is carried out by changing the discharge gap in the high-voltage spark gap 6 with an excess of voltage generated in the high-voltage direct current source 7, the charge current of which is limited by the resistor 8. The magnetic field is maximum in the center of the cross-section of the round turn 3, with which the thread 1 is aligned, and the latter with an ultra-strong magnetic field of a certain size and with the selected weight of the stretching thread 1 load 2 "bites" like scissors.

The magnitude of the load 2 is selected based on the Young's modulus for a given ferromaterial and the cross section of the thread 1 so that the stretching of the thread is critical, close to the possibility of its breaking by the action of the load 2 in the absence of a magnetic field. Therefore, the action of a magnetic field during the explosion of a round turn 3 is an additional factor determining the breakage of thread 1.

As the material of filament 1, rare earth metals can be used - gadolinium Gd (268.4 G / g), terbium Tb (328 G / g), dysprosium Dy (350.5 G / g), holmium But (347 G / g) and others, as well as their compounds [11-13]. In parentheses are the values of the saturation magnetization of the ferromagnet per gram of material.

Note that the duration of the discharge current in the round turn 3 should be significantly (several times) higher than the constant relaxation of the magnetic viscosity of the studied ferromaterial, which is ensured by the choice of the battery capacity of the high-voltage capacitors 5. The discharge process is aperiodic. The typical relaxation time of the magnetic viscosity of ferromagnets is chosen to be of the order of 0.5 ms and can be measured by appropriate devices [14].

The study of the magnetophysical properties of rare earth metals and their compounds is of interest in the creation of various technical devices, including the creation of magnetic motors that use the thermal energy of the environment, for example, the thermal energy of water basins, constantly replenished by solar radiation [15]. Along with the studies under consideration, it is necessary to use ferromagnets with the specified values of their magnetic viscosity and the highest possible magnetocaloric activity, with a high maximum magnetic susceptibility at relatively small values of saturation induction, to create the indicated magnetic motors (the latter reduces the requirements for the permanent magnets used in such magnetic motors, which create saturating magnetic field localized in space for applied ferromagnets).

Thus, in the inventive method, operations of introducing a centrally symmetrical round coil 3 of a ferromagnetic thread 1 of ferromagnetic material, as well as stretching this vertically suspended thread 1 with a controlled load applied to it in the form of a weight 2 of a given weight, are carried out. At the same time, the round turn is part of the explosive magnetic generator with adjustment of the magnitude of the superstrong magnetic field.

Literature

1. Preobrazhensky AA, Bishard EG, Magnetic materials and elements, 3rd ed., M., 1986;

2. Vonsovsky S.V., Magnetism, M., 1971;

3. Landau LD, Lifshits EM, Electrodynamics of continuous media, 2 ed., M., 1982;

4. Sakharov AD, Explosive magnetic generators, "Physics-Uspekhi", 1966, vol. 88, c. 4, p. 725;

5. The technique of large pulsed currents and magnetic fields, M., 1970;

6. Montgomery DV, Obtaining strong magnetic fields using solenoids, trans. from English., M., 1971;

7. Knopfel G., Superstrong pulsed magnetic fields, trans. from English., M., 1972;

8. Lagutin AS, Ozhogin VI, Strong pulsed magnetic fields in a physical experiment, M., 1988;

9. Strong and superstrong magnetic fields and their application, trans. from English., M., 1988;

10. Pavlovsky A.I., Magnetic cumulation, "Nature", 1990, No. 8, p. 39;

11. Rare-earth ferromagnets and antiferromagnets, M., 1965;

12. Taylor K., Darby M., Physics of Rare Earth Compounds, trans. from English., M., 1974;

13. Amorphous magnetism, ed. by H. O. Hooper, de A. M. Graaf, N. Y., 1973;

14. Menshikh OF, Instrument for measuring the magnetic viscosity of ferromagnets, RF Patent No. 2338216, publ. in the bull. No. 31 dated November 10, 2008;

15. Smaller OF, Method for producing energy and a device for its implementation, RF Patent No. 2332778, publ. in the bull. No. 24 dated 08/27/2008.

Claims (1)

A method for detecting a rupture of a ferromagnetic thread in a localized superstrong magnetic field, based on the use of an explosive magnetic field generation generator based on a coil of an exploding wire, characterized in that a centrally symmetrically loaded ferromagnetic filament of a ferromagnetic material, for example, a thin wire of rare-earth metals, is introduced inside a coil of an exploding wire or their compounds, which are stretched by the load applied to it.