SU1455327A1 - Method of determining transverse electric resistance of multifibre superconducting wire - Google Patents

Abstract

The invention relates to the measurement of active electrical transverse resistance of a multi-fiber superconducting wire. The accuracy of determining the transverse resistance is achieved by eliminating errors due to the shunting effect of a stabilizing sheath made of normal metal, the inability to control the quality of the junctions and the shunt effect of solder, the complexity of sample preparation, a decrease in useful signal. When measuring the transverse resistance, an electric current is passed along the wire, an electrical voltage is recorded along the wire, and the transverse resistance is determined using the experimentally derived formula. iS

Description

one

The invention relates to a method for measuring electrical characteristics, namely, a method for measuring active electrical resistance, more precisely, the transverse resistance of a multifilament superconducting wire.

The purpose of the invention is to improve accuracy.

The relationship between the transverse resistance of the multi-fiber superconducting wire R and the voltage U is due to the universal feature of the superconductor, namely the exponential shape of the current-voltage characteristic of the superconductor in a wide range of electric fields E.

E E, exp (-ill),

ten

- 15

I i. where E is the electric field in the superconductor;

current flowing through superconductor /

the critical current of the superconductor, the magnitude of the current I corresponds to the electric field Ef., usually taken to be equal to I-V / CM; The current parameter of the rise of the electric field in the superconductor (as the current I increases by „the electric field increases in e focHosa natural logarithms 2,718 ...) times.

I ate ate

05

Indeed, the differential resistance of the superconductor is 20

R

cti

Cn

R,

dE / dl

EC -rr-exp

0

 E / I,

(-)

 o

Cn

Those. The differential resistance of a superconductor increases in proportion to the electric field in it. Consequently, the transverse resistance of the drive in the region from the current contact to the point with the X coordinate can be both greater than the resistance of the superconductor, or less, depending on the level of the electric field.

R x

EX 1o

In this case, the current flows mainly either along or across the wire, respectively.

The non-linear connection between the electric field and the current in the superconductor does not provide an analytical solution for the redistribution of the transport current in the multi-fiber superconducting wire. But the result1455327

preparing the sample (since it does not require mounting the sample from individual pieces of wire), decreasing the weights f. signal (since it allows the choice of the coordinate of the first potential contact to obtain the desired value of the useful signal for its accurate measurement), i.e. As a result, the accuracy of determining the transverse resistance of a superconducting multifilamentary wire is improved.

The method is carried out in the following manner.

15 Take a sample of the wire selected for the test, diameter d, length. The fulfillment of this condition is not necessary for the measurement, but is necessary for

20 ensure high accuracy, since at this length, even in the presence of resistive barriers at the boundary of the superconductor and the normal matrix, the distribution

25 current density, over the wire cross-section, allows to obtain the maximum value of the measured signal. One of the cross sections of the sample parameter on the strip width is soldered

experimental studies

and mathematical modeling show- 30 first current lead, for example, from that

It is claimed that the maximum electric field due to the current redistribution over the wire cross section:

Consequently, the corresponding voltage between pins X and X along the wire is described by the expression:

Hg

and.

Е dV 2RI,

.

R

Up X, Xa 2X0 Xj-X

Xj- X X, Xj

(one)

Thus, the errors caused by the shunting effect of the stabilizing shell from

45 Nala is reduced due to overflow at the second tone contact. The method of soldering the second tone contact is not regulated, since it does not affect measurements at an extra-normal metal (such as the condition. The sample is mounted on a measuring probe, cooled to a temperature lower than T for a given superconductor, and removed the current characteristic 55 using the standard four-point method.

on the conduction of this path is extremely small compared to the flow of current into the superconductor due to the choice of sample length 1 1OOd), the inability to control the quality of the layers and the shunting effect of solder (since there are no such junctions between the potential contacts between the potential contacts), the difficulty of pressing the wire. Fulfillment of this condition makes it possible to consider the current lead linear.

At a distance X, B from the first current lead, the first potential is soldered

35 Social contact from a normal metal with a diameter of d, i.d. The fulfillment of these conditions makes it possible to increase the accuracy of counting contact coordinates. The second potential contact is implemented similarly to the first, but at a distance X, from the first tone contact to obtain the maximum signal, since, subject to the condition, the value of the useful signal is reduced due to the overflow from the second tone contact. The method of soldering the second tone contact is not regulated, since it does not affect measurements when it is applied to a measuring probe, cooled to a temperature lower than T for a given superconductor, and the current-voltage characteristic 55 is removed using the standard four-point method. At this or after this, the current-voltage characteristic is logarithmized and, by the slope of its linear portion (exponential),

the current parameter of the rise of the electric field IQ, and the parameter U .. is determined at the beginning of the linear section. The values of X ,, are measured (determined) on a measuring microscope. From the values obtained, the magnitude of the transverse resistance is determined.

Claims (1)

Invention Formula A method for determining the transverse electrical resistance of a multi-fiber superconducting wire, which involves passing an electric current through a wire using current contacts, registering an electrical voltage using potential contacts, and determining the resistance, characterized in that the Editor of L. Pcholinsk is passed to improve accuracy Compiled by L. Sorokin Tech red by M. Khodiich Order 7454/54 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 Production and printing company, Uzhgorod, st. Project, 4 The current along the wire, using current contacts located at the ends of the wire, records the dependence of the electric voltage between potential contacts along the wire on the magnitude of the transmitted electric current, determines by means of the logarithm of this dependence, the current parameter of the rise of 1 electric voltage in the exponential section and voltage start exponential plot and the transverse electrical resistance of the wire R is determined by the formula p "L2 Xg Xtt 2I / (Xj-X,) 20 where X and X are the distances from current contact to potential contacts. Proofreader V. But ha Circulation 711 Subscription