RU2087956C1 - Superconducting cable - Google Patents

Abstract

FIELD: electrical engineering. SUBSTANCE: cable has encased tubular conducting members filled with coolant, channels for forward and reverse pumping of auxiliary coolant, sheath, and evacuated cavities. Forward auxiliary-coolant pumping channel is located between external conducting member and sheath. Outer surface of the latter carries cryoinsulation and auxiliary-coolant reverse pumping channels. Evacuated cavity is provided between cryoinsulation and case. Inner surfaces of conducting members are covered with two layers of superconducting material and semiconductor material layer inbetween; it also carries waveguide parts. Sheath is made of conductor material and cryoinsulation, of alternating layers of aluminium oxide, titanium oxide, palladium, and granular adsorbent shielded by gauze. EFFECT: improved reliability of cable, reduced coolant consumption, enlarged capability of energy transmission and data conveying capacity. 3 dwg

Description

 The invention relates to superconducting devices and information transfer devices.

 A superconducting cable is known in which the superconducting cable itself, cooled by liquid helium, is placed in a sheath that is protected from thermal effects by an intermediate heat shield and vacuum-multilayer insulation. As a superconducting material, a niobium layer deposited on a copper tube is used. (A.B.Grachev, N.V. Kalinin. Obtaining and using low temperatures M. Energoizdat, 1981, p. 104-106). However, in this design, heat losses are not excluded.

 The closest set of essential features to the proposed device is a superconducting cable in which coaxial tubular conductive elements filled with refrigerant, tubular channels for direct and reverse pumping of auxiliary refrigerant, a sheath and evacuated cavities are placed in an isothermal housing. (Polytechnical Dictionary, edited by A. Yu. Ishlinsky. M. Soviet Encyclopedia, 1980, p. 465-466).

 The disadvantage of this design is the presence of a large number of hermetic vacuum and cryogenic shells that increase the cross section, weight and reduce the reliability of the structure.

 The objective of the present invention is to increase the reliability of the design, reducing the consumption of refrigerants, as well as increasing the types of transmitted energy and the amount of information.

 1. The problem is solved due to the fact that in a superconducting cable, including coaxial tubular conductive elements located in an isothermal housing, tubular channels filled with refrigerant for direct and reverse pumping of auxiliary refrigerant, a sheath and evacuated cavities, in contrast to the prototype, an auxiliary refrigerant pumping channel located between the outer conductive element and the casing, on the outer surface of which cryo isolation and auxiliary pumping channels are located about the refrigerant, between the cryo insulation and the body there is a vacuum cavity, while the cryo insulation is made in the form of alternating layers of film coatings of aluminum oxide, titanium oxide, palladium and a granular adsorbent protected by a enclosing mesh, two layers of superconducting material are deposited on the inner surfaces of the tubular conductive elements placed between they are a layer of semiconductor material and installed waveguide elements, and the shell is made of conductive material.

 When implementing the invention, a technical result is created, which consists in the following.

 In known superconducting cables, the temperature fields created by the primary and secondary refrigerants are isolated from each other by evacuated cavities, which complicates the mutual influence of these fields on each other. This leads to an unproductive loss of both temperature fields and, consequently, to the extra costs of the “cold” supplied by the refrigerants when creating superconductivity. Thus, the presence of a vacuum gap reduces heat transfer between thermal fields only to radiant heat transfer (due to radiation), i.e., vacuum played the role of an insulator. By removing this insulator, we carry out heat transfer through heat transfer through the "thermal bridge" created between the cryogenic thermal fields. Due to this bridge, heat transfer is enhanced by heat transfer through the conductor, which reduces the consumption of cold carriers of these fields, and this reduces the consumption of refrigerants, i.e. reduces the cost of superconductivity.

 Energy and information are transferred through a superconductor with a current (around which the main field of cryogenic temperatures is created to ensure the effect of superconductivity) due to the transfer of wave energy, for example, acoustic or electromagnetic waves through this superconductor. These waves will be carriers of information transmitted according to known laws and methods.

 Sound waves along such a conductor, where the attenuation is reduced to a minimum, propagate as in a sound guide with virtually no loss of absorption over long distances.

 This effect can be used not only for energy transfer, but also for information transfer, like optical fibers and other waveguides.

 In this case, the external magnetic field does not penetrate the superconductor due to the Meisner effect, which protects all types of wave energy transmitted through the waveguide, including the energy of electromagnetic waves, from the influence of interference from external electromagnetic fields.

 It is also known that the absorption of acoustic waves decreases with superconductivity and even negative absorption (i.e., amplification) of the acoustic wave signal in a semiconductor is observed. In the mode of negative sound absorption, the superconducting cable acts as an amplifier stage in acoustic communication and information transmission systems. Thus, theoretically there are no prohibitions on enhancing the mutual influence of temperature fields due to thermal bridges and their heat transfer and wave energy transfer, and with its help information on the same thermal bridge and superconductor.

 At the same time, the implementation of cryo isolation in the proposed manner allows to obtain a vacuum that provides reliable thermal and electrical insulation, without the accumulation of residual gases. A multilayer sorption coating in the form of alternating layers of film coatings of aluminum oxide, titanium oxide, palladium and granular adsorbent works as a "molecular sieve" (Soviet Encyclopedia. Dictionary, SES, p. 832, M. 1980 ed. S-Encyclopedia under the editorship of A. M. Prokhorov), i.e. passes some molecules, while others absorbs, i.e. due to different coatings, it pumps out all available residual gases, and most of the most common ones are pumped out with an adsorbent, commercially available for sorption pumps and vacuum cryogenic equipment.

 Since the "molecular sieve" is deposited on a conductive pipe cooled to cryogenic temperatures, which has a potential relative to the grounded casing, the residual gases begin to move to the "molecular sieve" under the influence of this potential difference.

 Since the residual gases are strongly discharged, the ionization threshold decreases, and it is fully provided with a small low-power ionization source, such as an ionization gauge for measuring vacuum, which measures vacuum by passing particles of residual gas through itself.

 The ionized residual gases are accelerated by the voltage between the current lead and the casing and fall into a "sieve" where they receive a negative missing charge, increase their volume and get stuck in a "sieve", which turns into a "molecular trap".

 The “potential barrier” thus created on the surface of the sorption coating prevents the exit of sorbed molecules and residual gases from the “molecular trap”.

 In the current lead, as you know, the excess of negative carriers of electricity and the lead will always have a negative potential compared to a grounded case, so the potential barrier will be a reliable gate to the "trap".

 Thus, the proposed combination of essential features of the invention provides a solution to the problem with the achievement of the specified technical result.

 The invention is illustrated by drawings, where in FIG. 1 shows a general view of a superconducting cable (section), in FIG. 2 conductive element (cross section), in FIG. 3 cryo-insulated sheath (section).

 The superconducting cable contains an isothermal housing 1 in which coaxial conductive elements 2, 3 are placed. The channels 4, 5 formed by the elements 2, 3 are filled with the main refrigerant (helium). Channel 6 between the external conductive element 3 and the shell 7 is used for direct pumping of auxiliary refrigerant (nitrogen). Channels 8 for the reverse pumping of auxiliary refrigerant are located on the outer surface of the shell 7, which can be made, for example, of aluminum. Between the casing 1 and cryo-insulation 9, deposited on the outer surface of the sheath 7, there is a vacuum cavity 10. The casing 1 is equipped with safety valves 11 and bursting membranes 12 installed along the cable with a certain step, for example, after 10-15 cm.

 On the inner surfaces of the conductive elements 2, 3, two layers 13 of superconducting material are applied, between which a layer 14 of a semiconductor material, for example, ferrite or germanium, is placed. The waveguide elements 15 mounted on the outer layer 13 of the superconducting material are used to transmit electromagnetic waves of different frequencies and ranges.

 Cryo-isolation 9 is made in the form of alternating layers 16, 17, 18 of film coatings. Alumina layer 16, titanium oxide layer 17, palladium layer 18. Between the enclosing mesh 19 and the coating 16, granular adsorbent 20, for example, activated carbon coated with a film of palladium and platinum, is poured.

 The device operates as follows.

The main (helium) is supplied to channels 4 and 5, and auxiliary (nitrogen) refrigerants to channels 6 and 8, having previously created a vacuum in cavity 10, for example, using fore-vacuum pumps, usually up to 7 • 10 ^-4 torr. Further, the vacuum is created using sorption and cryosorption processes of special sorbents 20 and film coatings 16, 17, 18. The coating, consisting of layers 16, 17, 18, acts as a "molecular sieve", i.e. each of these layers absorbs a certain group of atoms, and together these film coatings absorb almost all residual gases: palladium absorbs helium, platinum hydrogen, and aluminum oxide absorbs the remaining residual gases. The granular sorbent 20 absorbs and pumps out water vapor, heavy molecules and residual gases, and thanks to platinum-palladium films it additionally absorbs hydrogen, helium. The stepwise shape of the coating allows all molecules to access each coating simultaneously.

 Since under high vacuum the basis of the residual gases is helium and hydrogen, therefore, coatings 17 and 18 are made external.

 Using the potential difference between the shell 7 and the housing 1, the molecules and ions of the residual gases are accelerated and absorbed by cryo-insulation 9.

 The residual gases are ionized in the PMI type deep vacuum meter, which simplifies the potential difference of the current lead 7 and the housing 1.

 The negative potential of current lead 7 locks up the absorbed ions and molecules in the "molecular sieve" and turns it into a "molecular trap", does not allow the sorbed gases to escape back into vacuum. Thus, reliable vacuum insulation of the cable is created. After the formation of vacuum in the cable, the heat gain to the cryogenic part decreases and the consumption of refrigerants decreases.

 Due to the mutual influence of the main and auxiliary refrigerants through the common walls 2 and 3, the consumption of cryo-liquids is reduced even more. The mutual influence through channels 6 and 8 reduces the consumption of additional auxiliary cryoproduct.

 Walls 2, 3, 7 are cooled to cryogenic temperatures, conditions for the implementation of superconductivity are prepared.

 When current conductors 2 and 3 are reached, the superconducting temperatures begin to transfer electric energy through them as through superconductors, and electromagnetic waves of different frequencies and ranges are transmitted along waveguides 15 (they can also be optical fibers, for example, on conductive 2, waveguides 15 serve for the high-frequency range of electromagnetic waves, and on the current lead 3, the waveguides 15 serve for the optical range).

 After stabilization of the superconductivity mode, taking into account the work and waveguides 15, conductors 2 and 3 begin to transmit acoustic information.

 Due to the Meisner effect, superconductors 13 create a reliable electric field in a semiconductor 14 made of germanium or ferrite, protected from external electric fields and interference, which creates the conditions for the appearance of negative absorption of sound and ultrasonic waves in such a semiconductor. Under these conditions, acoustic waves are transmitted without loss and even amplified, i.e. Such a cable works not only as a communication channel, but also as an amplifier of the transmitted acoustic signal and electromagnetic waves. Considering that germanium is optically transparent for the infrared range of electromagnetic waves, it is also possible to transmit optical information through this current path, such as through a fiber using infrared lasers. Since the laser radiation of the infrared region of the spectrum, acoustic waves, HF electromagnetic and radio waves belong to different ranges of the electromagnetic wave scale, they do not interfere with each other, and in the proposed cable, the cross-section and weight are reduced compared to the prototype due to the absence of intermediate vacuum insulation belts, increased design simplicity, etc., an unprecedented density of transmitted information is achieved due to superconductivity and negative absorption at cryogenic temperatures rah result of combining these phenomena when creating thermal bridge between the refrigerants.

 In an emergency, if one of the refrigerants is cut off, safety valves 11 and bursting discs 12 are activated, which release the gas pressure during desorption into the atmosphere and keep the structure from damage.

 The design of the proposed SPK (superconducting cable) allows you to transmit wave energy information through the conductive elements, allows you to use them as waveguides, since the material of superconducting coatings from Germany falls into the transparency interval of the optical waveguides, and the coating from ferrite into the transparency window of the radio waves, and all conductive elements including superconducting coatings have the ability to transmit acoustic and sound information and sound and acoustic waves, like all solid body, and especially superconductors.

 The cryo-isolation method of the cable allows its insulation to be used in cryovacuum devices and devices when using a "molecular trap" in them.

Claims (1)

 A superconducting cable including coaxial tubular conductive elements located in an isothermal housing filled with refrigerant, tubular channels for direct and reverse pumping of auxiliary refrigerant, a sheath and evacuated cavities, characterized in that the channel for direct pumping of auxiliary refrigerant is located between the outer conductive element and the sheath, on the outer the surface of which has cryo-insulation and auxiliary refrigerant back-flow channels, and between the cryo-insulation and the body a vacuum cavity is located, while cryo isolation is made in the form of alternating layers of film coatings of aluminum oxide, titanium oxide, palladium and a granular adsorbent protected by a protective mesh, two layers of superconducting material are deposited on the inner surfaces of the conductive elements with a layer of semiconductor material placed between them and waveguide elements, and the shell is made of conductive material.

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