DE1097013B - Conductor arrangement for cryotron circuits and process for their production - Google Patents

Description

GERMAN

The invention relates to a conductor arrangement for cryotron circuits with a controlled conductor section made of a superconducting material with a predetermined critical field strength and a control conductor made of one superconducting material of relatively high critical field strength and process for their manufacture.

The invention will be described in relation to the problem and solution in the following with reference to schematic drawings explained in more detail.

Fig. 1 shows' a family of curves for different materials, and it shows in which way the temperature at which the material becomes superconducting depends on an applied magnetic field changes; the specified materials are superconducting when kept under those conditions by the ones to the left of the curves in question or below the curves Surfaces are represented;

Fig. 2 is a schematic representation of a known one Cryotrons;

Fig. 3 shows schematically a cryotron flip-flop circuit, can be used in the cryotrone of the embodiment of FIG. 2;

Fig. 4 is a section through a base conductor in which certain sections are provided with coatings of different superconductivity properties;

Fig. 5 is a longitudinal section through the conductor of Fig. 4 with the coating diffusing into the conductor to make a cryotron conductor according to the invention;

Fig. 6 shows in longitudinal section a further embodiment of a composite cryotron conductor according to the invention;

7 schematically illustrates the manner in which several interconnected cryotrons made of conductors the type shown in Figures 3 and 4 can be made;

8 schematically shows the cryotron flip-flop circuit according to FIG. 3, which is composed of several cryotrons constructed according to FIG.

In all of the figures, similar parts are denoted by the same reference numerals.

As is known, cryotron circuits consist of a controlled conductor section made of a superconductive one Material with a predetermined critical field strength and a control conductor made of a superconductive material of relatively higher critical field strength. The critical field strength is the strength of a magnetic field understood, in which the ohmic resistance of a being in the superconducting state Conductor again assumes a predetermined finite value without changing the temperature. Cryotron circles can be used, for example, as logical circles in arithmetic units.

Conductor arrangement for cryotron circles
and methods of making them

Applicant:
International

Business Machines Corporation,
New York, NY (V. St. A.)

Representative: Dr.-Ing. F. Wuesthoff, Dipl.-Ing. G. Pulse

and Dipl.-Chem. Dr. rer. nat. E. Frhr. v. Bad luck man,

Patent Attorneys, Munich 9, Schweigerstr. 2

Claimed priority:
V. St. v. America July 11, 1957

Howard O. McMahon, Lexington, Mass. (V. St. A.),
has been named as the inventor

Fig. 1 shows that a magnetic field of 50 to 100 Örsted causes a wire aus_Tantal, which is at a temperature of 4.2 ° K, d. i.e. “at the boiling point of liquid helium at atmospheric pressure, from its superconductive state to the state of resistance transforms.

FIG. 2 further illustrates a known cryotron with a central or blocking conductor 2 on which a control winding 4 is wound; Both the blocking conductor and the winding are made of materials that are normally superconducting at very low temperatures. The entire unit is immersed in liquid helium, around the blocking conductor 2 and the

4.0 To make control winding 4 superconducting. If sends a current of sufficient strength through the control conductor, causes the thereby evoked Magnetic field that the blocking conductor changes from the superconducting state to the resistance state. Thus, the control winding together with the blocking conductor forms an electrically operated one Switch in which the blocking conductor is switched off by sending a current through the control winding the state of superconductivity can be converted into the state of resistance.

Tantalum is a useful material for such blocking conductors because its transition temperature is in the range from 50 to 100 örsted is at 4.2 ° K, the boiling point of helium at a pressure of one atmo-

009 698/397

Sphere. This temperature can be erreii & env without ^': combination comprising the conductor Kig, complicated equipment is in that it is necessary, this time,' a resistor. Thus, the total current supplied by the power source for generating pressure or negative pressure flows to,,. _{: use} the blocking conductor KIg while through the conductor KIg . ^Niobium: a relatively high critical ■ _. 5 _; no strain; flows, - and the same due to the control field strength, is usually used for the control winding K Ic flowing current holds the associated winding, because it is desirable and in the blocking conductor if lg · in its resistance state. In some cases it is also necessary that the control conductor flip-flop circuit is stable in this state during the entire operation of the cryotron and thus remains conductive, and the control winding is essentially bistable vacuum tubes -Flip-flop circuit, which is stable in borrowed the same magnetic fields · exposed to one or the other state. When the blocking conductor. Furthermore, in most applications, the current available from the power source is less than is desirable, the control conductor in the form of a winding double the value of the current that is determined, e.g. B. as winding 4 in Fig. 2, so that - is necessary to call the critical field strength only a current of the lowest possible strength 15, and if an Im needed to the control winding K 3 c in order to achieve the critical field strength. pulse is applied to a in the blocking conductor K 3 g

In Cryotron circuits, the blocking conductor will cause a conversion, so that the current path comprising the conductor Cryotron often shows a resistance with the control winding of another KZg, Cryotrons are connected in series, and therefore the current must be distributed in approximately equal parts to provide Cryotron with a current amplification when the 20 on the two current paths. Now the control circuit should work properly, that is, a current flows through the conductor if Ic, which does not have to be sufficient to power the blocking conductor of the cryotron to make the blocking conductor K 1 g stronger than the one to feed the associated state to keep. When the blocking conductor K Ig control winding required current. If the control of the resistance state into the superconducting conductor nieht designed as a winding, it can forward 25 state transitions, it forms a superconducting current coming that the current through the control conductor away, the c also through the control conductor K2 the must be sent to extend the for the blocking conductor from blocking conductor K 4 g · and the control conductor K6c ; Tantalum to achieve the required critical field strength, thus the entire available current flows through this generates a field that is strong enough to create a current path, so that in the blocking conductor K 2 g a so-called self-displacement of a conversion in series is brought about will. In this way switched blocking conductor made of tantalum to be effected. In the range of the flip-flop circuit its other stable practice, it has been shown that one means of a state.

Cryotrons achieve a suitable current gain in a similar way, causing an on the control conductor

can, if the diameter of the blocking conductor from K 4c applied current pulse of sufficient size,

Tantalum is about 0.23 mm and when the control 35 that the flip-flop circuit is in its previous state

winding from returns applied in a single layer. Depending on whether the superconducting

Turns of niobium wire with a diameter of current through the flip-flop circuit via the

of about 0.075 mm, whereby the number of the Win control ladder extends to K5 c or the control ladder if 6 c,

fertilize about 10 turns / cm. is either in the blocking conductor K Sg or in the

A simple bistable element, as it is required as a blocking conductor if 6 g · a conversion, and the basic element of a binary numeric calculator, therefore showing the conductivity states of this blocking required, can be used to trace the state of the flip-flop from cryotrons in the A way. Circuit if 1-if 2 on. build that one connects the blocking conductors of two such In view of the small dimensions and the low aggregates in parallel and ensures that the low costs forms the Cryotron an ideal basic or other blocking conductor conducts the entire current through 45 laying switching element for use with extensive the combination in the same way as devices for processing information, like a flip-flop circuit made up of vacuum tubes in which many thousands of such elements are used. According to FIG. 3, a known cryotron flip-flop circuit can be used in a number of basic circuits. B. in the manner of the flip-flop circuit according to FIG. 3, trone if 1 and if 2, whose blocking conductors if lg · 50 are connected to one another. Up to now, the ge and if 2 g · led to one end together with a current ring size of the individual cryotrons, which are connected in the source, which is shown in FIG ; in series with the blocking conductors, there is considerable difficulty in establishing a limiting resistor. The resistance position of the various circuits in which Cryoil possesses preferably a significantly higher 55 trone are used. The four terminals of each cryo-resistor act as the flip-flop circuit, so that the trons are generally connected to other superconducting power sources to provide a substantially constant current to circuit elements by welding. The blocking conductor KIg is connected in series with the control winding, the superconductivity at the connection points if 2 c, and the blocking conductor if 2 g Cryotron about connected on average. To complete the circuit, two welds; the flip-flop circuit after the control conductors are used for inputting Fig. 3 has z. B. ten inner welded joints, Cryotrone if 3 and if 4 as well as for removal which are denoted by the reference numerals 7 to 24. The result-serving cryotrone if 5 and if 6 in the diameter of the individual blocking and control conductors in a manner to be described below to earth. If 65 Cryotrone can down to about 0.025 to about the conductor if Ig-has a resistance - while it is 0.050 mm, and therefore one has to deal with these elements with these elements and with The constant superconducting current path through the blocking conductor position of the welded connections with the greatest pref2g and if 3 g as well as the expensive conductors if 1 c and if 5 c. sees work so that no breaks occur and that the current path through the series connection 70 connections is established in the correct manner.

the. In the. Practice becomes the gryotron postures therefore mostly under one. Microscope made and it This is a time-consuming one. and tedious Job. .- ■ -: ■ · .-:

An older proposal concerns a Gryotron circuit, in which the magnetic field of a control coil in such a way a number "of ladders acts that the ladder at Increase in the magnetic flux in a predetermined order one after the other from the superconducting go into the normally conducting state. Either an inhomogeneous control field is used for this, so that the field at the individual ladders comes into effect differently, or the material of the conductor is chosen so that the critical field strength for the individual conductors at different Values.

In contrast, it is the object of the invention to create a conductor arrangement for cryotron circuits, with any cryotron circles in a simple manner and with only a very small number of connection points can be produced. For this purpose, the invention provides at least one one-piece band- or wire-shaped conductor made of superconducting material, which adjoins one another over its length Has areas of different critical field strength. The order and size of the consecutive Sections can be different. The different sections advantageously follow each other periodically, and sections of the same field strength also have the same length.

With the new conductor arrangement one obtains in one operation and with a one-piece conductor material at the same time the controlled and the controlling ladder sections, which are essentially different differentiate between critical field strengths. This allows not only individual cryotron elements, but Build whole cryotron circles from the same one-piece conductor material. This simplifies Not only the production, but also the processing of the conductor material is essential. It is z. B. not infrequently that controlling and controlled superconductors are electrically in series. Such a circle leaves with the conductor arrangement according to the invention in a simple manner and a significantly lower number of solder points than in the known arrangements.

Accordingly, a composite conductor with two blocking conductor sections and two control conductor sections can be used in place of the blocking conductor KIg, the control winding K2c, the blocking conductor K & g and the control winding K6c according to FIG. 3; accordingly, a ladder of this type can be provided in place of the rest of the blocking and control ladder. The two assembled conductors are to be connected to one another at 7 and 24, and in this way the number of internal connections in the arrangement according to FIG. 3 is reduced to two, ie to 20% of the connection points previously required.

The composite cryotron conductor according to the invention can comprise a tantalum wire which is provided in sections with a coating of niobium, the sections not having a coating serve as blocking conductor sections, while the sections provided with coatings, in which a considerably greater critical field strength is required, act as control conductors. Alternatively, a different material can be diffused into a wire made from a base material with certain superconducting properties at every second section in order to change the properties of the sections concerned, so that different critical field strengths apply to the treated and the untreated sections.

In Fig. 5 is a manufactured according to "the invention composite cryotron conductor shown. ■ According to Fig. S comprises the overall designated 26 conductor Alternating control line segments 28 made of niobium and blocking conductor segments 30 made of a niobium-tantalum alloy. As from Fig. 4

ίο can be seen, the conductor 26 can be produced in such a way that that first on a wire 34 made of niobium at suitable intervals coatings 32 made of tantalum brings up. The coatings 32 can be made by any suitable method,

»5 z. B, by vapor deposition, electroplating, etc. The The wire carrying the coatings is then kept at a suitable elevated temperature for a sufficiently long time so that the tantalum coatings diffuse into the niobium conductor. This gives you

so the assembled conductor 26 according to Fig. 5, in which the untreated sections 28 made of niobium die Have properties of control conductors where a higher critical field strength is required while the sections 30 made of a niobium-tantalum alloy have the properties of blocking conductors, d. H. require a lower critical field strength.

Another cryotron conductor is shown in FIG. 6. In this case, the total of designated 36 includes Head a main conductor made of tantalum, which consists of control conductor sections 38 and 38 coated with niobium consists of blocking conductor sections 40 made of tantalum which have no coating. The coatings of niobium can similar to the coatings 32 of FIG. 4 by vapor deposition or electroplating be generated.

The diameter of the conductors 26 and 36 is preferably as small as possible and the lower limit for the diameter depends largely on the difficulties encountered in handling the conductors. In other words, the main conductors 34 and 40 are preferably made of wire having a diameter of about O ^1, 125 mm, and the non-treated portions of the finished composite conductor have the same diameter; in the case of the treated sections 30 and 38, the diameter can be somewhat larger; this is due to the introduction of additional material in these sections. The tantalum coatings 32 according to FIG. 4 should have a thickness which is sufficient to provide sections 30 whose conversion points differ so greatly from those of the control conductor sections 28 made of niobium that the circuit works properly; in other words, the difference between sections 28 and 30 with respect to the critical field strength should be at least 3: 1. The niobium coatings on sections 38 of FIG. 6 should be thick enough to ensure that the underlying sections of the ground conductor are completely covered.

Although the use of niobium and tantalum has been mentioned with regard to conductors 26 and 36, but it should be noted that other materials can also be used if they differ with regard to their transformation points differ considerably, so that when they are used in a cryotron circuit, the control line sections Remain superconducting, while the blocking conductor sections assigned to them are the critical ones Are exposed to field strength. It should also be noted that in an embodiment of the invention,

ι: bs T-i> i 3

seated ladder. - can be provided - the ex-. cut with. more than two different conversions include treatment points. For example, the " Head 36 according to Fig, 6 similar head in addition to those coated with niobium and those not treated '5 Delte sections of tantalum further. Have sections, that are coated with lead. With regard to the sections made of tantalum, a relatively small one would then be critical field strength · be given, while the lead-coated sections have a greater critical id Field strength and the sections coated with niobium require an even higher critical field strength.

In an embodiment of the invention, the superconducting wire can be used to build up several interconnected cryotrons as shown in FIG. In Fig. 7, the composite Lei have ¹ ter 42 and 44 respectively cutoff and drive lead portions 42 a and 42: bzw- 44a, and 44. These conductors can correspond to the embodiments of Fig. 5 or 6, and they are preferably wound with the aid of suitable machines to form a starting material with the desired number of sections, each section forming a single cryotron and each having a control conductor section of the one conductor is in the form of a winding surrounding a corresponding blocking conductor portion of the other conductor. Parts of the control conductor sections are also used as connecting wires between the various sections, so that when used later in operation, these connecting wires always remain superconducting within the circuit in question.

The superconductive starting material can be conveniently used in the manufacture of various kinds of Use cryotron circuits, both simple cryotron switches and the most intricate Circuits. As explained below, a suitable length can be used cut off the source material and perform various operations on it to create a Manufacture cryotron flip-flop circuit. Though The length of the various sections may vary, but it should be noted that it is generally desirable is that all sections with the same transformation points each have the same length, so that the starting material can be produced more easily.

FIG. 8 illustrates a flip-flop circuit constructed using the cryotron starting material of FIG. From the starting material there are six. Cryotrons separated as a finished unit ', and these form the cryotrons K1', K 2 ', KZ', K%, Ä5 ^A and K 6 'in FIG. 8. The conductors are welded together at one end in order to produce a connection 7 'similar to connection 7, and this connection point is connected to a battery 6' via a resistor R f. If the circuit according to FIG. 8 is followed from top to bottom, the connection point 7 'is followed by the cryotrons KV and K 2' , each of which is "" connected with its control winding to the blocking conductor section of the other conductor, as shown in FIG Fig. 3 is shown. At the Cryotron K 4 ', however, the starting material is changed by cutting it along the dashed lines 46 and 48 in order to isolate the control winding iT4'e, the connections of which are then used as input connections. The blocking conductor K4fg remains connected in series with the blocking conductor KX'g, as is the case in FIG. The connection between the blocking conductor if 3'g- and the control winding K 6'e is severed at 50, and the blocking conductor is made by a welded joint 52 ^; connected in series with the blocking conductor K2'g. The expensive winding KZ'c is isolated from the blocking conductors K5'g and K6'g ; as indicated by the dashed lines 54 and 56, and the cryotron KZ ' thus serves as the other input cryOtron: the blocking conductor iCö'g' isolated at -48 "and 54 and the blocking conductor K S'g insulated at 56 can then be used as a removal lock, for their control windings K6'c and K5'c are each ¹ with the input and locks K4tg KZ'g in series. the control windings and JT5'c K6'c are similar also by a weld 24 'of the weld 24 connected to one another in FIG. 3.

Thus, in terms of circuitry, the elements shown in FIG. 8 are in the same relationship to one another as their counterparts in Fig. 3, and the operation of the two circuits is identical. When switching 8, however, compared to the ten joints that are required; if if the circuit is built from individual cryotrons, only three internal connection points are required.

Claims (11)

PATENT CLAIMS: 1. Conductor arrangement for cryotron circuits with 'a controlled conductor section made of a superconducting Material with a predetermined critical field strength and a control conductor made of a superconducting Material of relatively high critical field strength, characterized by at least one one-piece strip or wire-shaped conductor made of superconducting material, which over its length to each other has subsequent areas of different critical field strength. 2. A ladder arrangement according to claim 1, characterized in that the areas with different critical field strength periodically follow one another. 3. A conductor arrangement according to claim 1 or 2, characterized in that the areas with the same critical field strength have the same length. 4. conductor arrangement according to claim 1 to 3, characterized in that the conductor consists of one Core consists of superconducting material, on which cladding sections from a superconducting material are applied, the critical field strength of which is different from that of the core is. 5. conductor arrangement according to claim 4, characterized in that; that the core of niobium and the Sheath sections consist of tantalum or an alloy containing tantalum. ■ 6. conductor arrangement according to claim 4, characterized in that the core made of tantalum and the Sheath sections consist of niobium. 7. ladder arrangement according to claim 6, characterized in that with two or more conductors in each case the areas with the higher critical "Field strength of one conductor, preferably in the form of a control winding, in the immediate vicinity of the areas with the lower critical field strength of the other conductor, and vice versa. 8. Method of making a conductor arrangement -according to claim 1 to 7, "characterized in that that; starting from at least "one · '· Ribbon or wire-shaped conductors made of superconductive! Material; the material of the conductor is so "influenced in some areas that its on a - certain 'temperature -related critical Field strength in successive areas varies, that in each case an area of high critical Field strength arranged in the immediate vicinity of an area with a lower critical field strength and that, if necessary, the individual cryotron units formed in this way from one another be separated. 9. The method according to claim 8, characterized in that lying on at mutual distances Areas of the one-piece conductor applied surface layers made of a material whose critical field strength differs from that of the conductor. 10. The method according to claim 9, characterized in that such a layer material with high critical field strength is used. 11. The method according to claim 9, characterized in that such a layer material with a lower critical field strength than the conductor material is used and that the conductor after application of the layer is heated to a temperature at which the layer material in the Conductor material can diffuse. Legacy Patents Considered:
German Patent No. 1 049 959. 1 sheet of drawings © 009 698/397 1.61