CN100359325C - Method for measuring critical current homogenity of every portion for super conducting strip - Google Patents
Method for measuring critical current homogenity of every portion for super conducting strip Download PDFInfo
- Publication number
- CN100359325C CN100359325C CNB031497756A CN03149775A CN100359325C CN 100359325 C CN100359325 C CN 100359325C CN B031497756 A CNB031497756 A CN B031497756A CN 03149775 A CN03149775 A CN 03149775A CN 100359325 C CN100359325 C CN 100359325C
- Authority
- CN
- China
- Prior art keywords
- superconducting tape
- magnetic field
- critical current
- hall probe
- field
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Abstract
The present invention relates to a method for measuring critical current uniformity of each part of a superconductive belt material, which belongs to the technical field of superconductive electricians. The present invention is characterized in that a background field magnet is switched with direct current, a stable constant direct current magnetic field is generated to be used as a background magnetic field, and the superconductive belt material passes through the background magnetic field; when the superconductive belt material moves outside the background field magnet, a Hall probe is used to measure residual fields of the superconductive belt material, the space in which the superconductive belt material is placed has no background magnetic field when the residual fields of the superconductive belt material are measured, the ratio of the residual fields of each part of the superconductive belt material is equal to that of critical current of each part of the superconductive belt material, more specifically the uniformity of the critical current of the superconductive belt material. The present invention has the advantages of no physical damage to the superconductive belt material, small work amount and great improvement of speed; furthermore, the present invention is suitable for measuring superconductive belt material with longer length. Both the production and using manufacturers of the superconductive belt material can use the present invention to control the quality of products.
Description
Technical field
A kind of method of measuring superconducting tape each several part critical current uniformity belongs to the superconduction electrical field.
Background technology
Superconducting tape generally be length between 100 to 1000 meters, cross sectional dimensions is approximately the long ribbon shape material of 4*0.2mm.In actual applications, need to understand the variation of superconducting tape critical current in axial direction.The so-called superconducting tape each several part critical current uniformity of measuring just is meant: be one section with several millimeters or longer distance on the superconducting tape axial direction, measure the ratio of critical current between each section, purpose is to detect between each section of superconducting tape in axial direction whether critical current has very big variation.The total length of setting superconducting tape is N*L, the critical current properties of measuring N section superconducting tape successively in measuring process, and N is an integer, referring to Fig. 1.
The method of existing measurement superconducting tape each several part critical current uniformity is mainly four leads method, and the absolute value of the critical current by measuring each section superconducting tape obtains superconducting tape each several part critical current ratio, the just homogeneity of critical current.Need measure the voltage at tested superconducting tape two ends when four leads method are measured the critical current of superconducting tape and flow through the electric current of this section band, will on superconducting tape, weld like this and go between in a large number in order to measuring voltage, this process is unquestionable will destroy band, and workload is heavy.The method visible " superconducting technology and application thereof ", National Defense Industry Press, first published was compiled the translator and was: Jiao Zhengkuan, Zhu Zhengang, Ning Yuhong, Zhang Qirui in February, 1975.
Other modes of measuring superconducting tape each several part critical current uniformity also comprise some non-contact methods, such as:
By measuring the superconducting tape each several part in the homogeneity of inferring superconduction belt material critical current by the ratio of the remanent magnetism under the AC magnetic field situation.The key step of this method is:
1. superconducting tape is put into provided magnet.
2. to magnet indirect current stream, power frequency produces alternating magnetic field less than 10Hz.
3. detect the variation that adds alternating magnetic field, when the value of externally-applied magnetic field is zero, measure the remnant field of superconducting tape.
4. the ratio of superconducting tape each several part remnant field equals the ratio of superconducting tape each several part critical current, just the homogeneity of superconduction belt material critical current.
The visible Bennie ten of the method Haken, Rob A.M.Budde and Herman H.J.ten Kate, " Continuouse Recording of The Transport Properties of a SuperconductingTape Using an AC Magnetic Field Technique " IEEE TRANSCATIONS ONAPPLIED SUPERCONDUCTIVITY, VOL.9.NO.2, JUNE 1996
The major defect of the method is:
1. owing to the back of the body field that superconducting tape is applied is interchange back of the body field, if it is too high to exchange the frequency of carrying on the back the field, will produce eddy current among the superconducting tape, noise signal is bigger, and measuring accuracy descends, so the frequency of interchange back of the body field can not be too high.Because measure the remanent magnetism of superconducting tape at every turn is when externally-applied magnetic field is zero, will cooperate the frequency of the interchange back of the body field during measurement, if it is slower to exchange the frequency of back of the body field, then measuring speed is also slow.In addition, under the situation that sample frequency can't improve, improve the spatial accuracy of measuring if desired, spatial accuracy can be interpreted as every remnant field of how many range observations, just must further reduce the speed of superconducting tape, that is to say that finishing long band critical current measuring task need spend more time by hall probe.
2. the employed equipment of this measuring method is more complicated also, at first, the AC power that output frequency is very low is not in daily use, and next will use lock-in amplifier in measuring process, and the purpose of using lock-in amplifier is to measure the magnitude of voltage of hall probe in changing back of the body field.The price of lock-in amplifier is higher, and debugging is also relatively more difficult.
3. measuring accuracy is difficult to guarantee, the measuring-signal of hall probe be background magnetic field and superconducting tape with the result of the common influence in magnetic field, in order to obtain the magnetic field of superconducting tape, need the measuring-signal of hall probe be compensated, to eliminate the influence of background magnetic field, this process is easy to introduce error.
4. if wishing multiple signals measures simultaneously, such as in measurement axis in critical current uniformity, utilize the Hall plate array that the radially critical current uniformity of superconducting tape is measured, at this moment need to measure simultaneously the output of a plurality of Hall plates, if adopting, background magnetic field exchanges back of the body field, can cause measuring equipment complicated more, even may not realize.
5. may run into bigger impedance when producing the copper coil of background magnetic field when alternating current, the size of electric current is restricted, and might not produce satisfactory magnetic field.
Summary of the invention
For overcoming the shortcoming of above-mentioned prior art, the invention provides a kind of new contactless measurement that utilizes and detect the inhomogeneity method of superconduction belt material critical current, be mainly used in the quality testing of superconducting tape, be specially adapted to and destroy the situation long to superconducting tape with superconducting tape length.
Technical scheme of the present invention is as follows:
The present invention passes to direct current to provided magnet, produces steady D.C. magnetic field magnetic field as a setting, and superconducting tape passes through background magnetic field.In the time of outside superconducting tape moves to the background magnet, utilize hall probe to measure the remnant field of superconducting tape.When measuring the superconducting tape remnant field, superconducting tape space of living in does not have background magnetic field.The ratio of superconducting tape each several part remnant field equals the ratio of superconducting tape each several part critical current, the just homogeneity of superconduction belt material critical current.
Measuring process of the present invention is specific as follows:
(1) utilize voltage table to measure the magnitude of voltage of hall probe under the situation that does not have the influence of superconducting tape remnant field as zero point, the measuring voltage value when hall probe is measured the superconducting tape remnant field will deduct this zero point;
(2) provided magnet is passed to direct current and produce magnetic field, superconducting tape moves in as the gap between the several-layer solenoid coil of a pair of copper cash coiling of provided magnet, magnetizes; In the measuring process, the steady D.C. magnetic field that the superconducting tape each several part produces by provided magnet successively;
(3) arrange hall probe in a side of provided magnet, hall probe is perpendicular to superconducting tape, and superconducting tape is successively by hall probe, and hall probe is measured the remnant field of superconducting tape each several part;
(4) the working voltage table is measured the output of hall probe, according to the output of voltage table, and the remnant field of the superconducting tape that the calculating hall probe collects;
(5) repeat above-mentioned steps successively, obtain the remnant field of superconducting tape various piece, promptly the remnant field of superconducting tape is along the axial distribution of superconducting tape; The distribution vertically of the remnant field of superconducting tape can be regarded as the critical current distribution vertically of superconducting tape, has so far just finished all processes that the critical current uniformity of superconducting tape is measured.
Measuring method of the present invention is based on following principle: superconducting tape can be captured a part of magnetic flux by behind the direct current back of the body, and the size of residual flux is proportional to the size of the critical current of superconducting tape.Remnant field can measure by hall probe, and the ratio of measuring superconducting tape each several part remnant field successively just can obtain the ratio of superconducting tape each several part critical current, the just homogeneity of superconduction belt material critical current.
Contrast four leads method, principal feature of the present invention is, the present invention measures superconducting tape by the remnant field behind the externally-applied magnetic field, rather than welding current and voltage lead are measured the absolute value of critical current on superconducting tape.The present invention does not have physical damage to superconducting tape, and workload is very little, and measuring speed greatly improves with respect to four leads method; And can detect the very trickle mass defect of superconducting tape, that is to say that spatial accuracy improves greatly.
The measurement superconducting tape that contrasts prior art is exchanging the back of the body method of capturing magnetic field after the match, owing to background magnetic field used in the present invention is direct current back of the body field, rather than exchanges back of the body field; When measuring the remnant field of superconducting tape, superconducting tape is in outside the provided magnet, rather than is among the provided magnet; When the remnant field of superconducting tape was measured, superconducting tape space of living in did not have background magnetic field, rather than in exchanging back of the body field, the remnant field of superconducting tape when interchange back of the body field is changed to zero.Based on above some difference, there is not the problem that cooperates with the frequency that exchanges back of the body field in the present invention, measuring speed can be adjusted according to the needs of self.Under the situation that does not change measuring speed, can improve the spatial accuracy of measurement by changing sample frequency; Equipment is also simplified greatly, with respect to the prior art of measuring in exchanging back of the body field, needn't use instruments such as signal generator, AC power, lock-in amplifier; The present invention also can avoid some to introduce the step of measuring error, and hall probe is placed on the place that certain distance is arranged with magnet, and radome is equipped with in the magnet outside, so without the influence of compensate for background magnetic field to hall probe; The Usage data collection card can be realized the measured value to a plurality of Hall plates easily, promptly gathers multiple signals the time, and equipment is simply effective, and price is lower; Owing to be to use direct current back of the body field,, can determine the size of provided magnet by provided magnet the time according to user's needs so the impedance that electric current runs into reduces greatly.
After control survey speed freely, spatial accuracy, sample frequency, background magnetic field, the superconduction belt material critical current uniformity measurement has had very big extensibility, the gauger can be freely changes measuring process according to oneself idea, obtain the measurement result that oneself needs, such as:
1. when the critical current uniformity of superconducting tape is measured, pulling force on the superconducting tape requires smaller, if can control the measuring speed of superconducting tape, in design superconduction belt material critical current uniformity measurement equipment, just can find the pulling force that had both made on the superconducting tape in limited range so, again the design proposal of measuring with fast speeds.
2. for the quality of superconducting tape each several part critical current uniformity is discussed, the standard deviation and the average that need the analysis to measure result, if spatial accuracy that can control survey just can find the best spatial accuracy of Analysis of Superconducting band critical current uniformity.
3., so just can make the size of background magnetic field just equal the magnetic field that penetrates of superconducting tape if the tester can control the size of background magnetic field; And under the situation of needs, can measure the remnant field of superconducting tape under the background magnetic field of different sizes and the remnant field distribution of superconducting tape each several part.
In sum, the present invention can make measuring speed adjust according to gauger's needs, can obtain very high spatial accuracy, can reduce equipment cost and debugging difficulty greatly, can obtain the higher measurement data of precision, can measure simultaneously superconducting tape vertically and critical current radially distribute.Because above-mentioned advantage, the method that present disclosure proposed is realizing that several critical aspects that critical current uniformity is measured have had large increase, utilize this method can fast, simply, effectively, accurately realize the inhomogeneity measurement of superconduction belt material critical current.
The present invention does not have physical damage to superconducting tape, and workload is very little, and speed greatly improves.Be applicable to the long superconducting tape of length is measured.At present, in power engineering, among superconducting power transmission cable, superconductive current limiter, superconducting motor, superconducting transformer etc. were being developed, all above-mentioned application all required superconducting tape to have good homogeneity.In actual applications, the homogeneity of measurement superconducting tape each several part critical current has very important meaning.
Principle of the present invention is: after belt material of high temperature superconduct passes through externally-applied magnetic field, can capture a part of magnetic flux, remaining this part magnetic flux can be measured comes out in the superconducting tape, can reflect the ratio of superconducting tape each several part critical current with the ratio of superconducting tape each several part remnant field.The present invention utilizes hall probe to measure each section of superconducting tape by the later remnant field of applying dc magnetic field, obtains the homogeneity of superconducting tape each several part critical current.
Superconducting tape is imperfect type, owing in non-ideal type, have crystal defect, so its magnetization curve is irreversible.The remanent magnetism of superconducting tape can be found out from the irreversible magnetization curve: when temperature was lower than the critical transition temperature of superconducting tape, the value of establishing externally-applied magnetic field was H, at first externally-applied magnetic field was raise from null field, and the magnetic induction density of sample is B, B＜μ
0H is elevated to H again
C2, when promptly the upper critical of superconductor mixed state was above, sample changed normal state into, B=μ
0H reduces magnetic field again to H
C2When following, B＞μ
0At this moment H has just existed and has captured magnetic flux, and when the vanishing of magnetic field, there is remanent magnetism B in sample
r
Crystal defect in the superconductor has produced flux pinning force, and magnetic field can be stoped in the turnover superconducting tape.When magnetic field was reduced to zero, magnetic flux line was because by crystal defect, and the prevention of pinning just and being retained in the superconductor forms remanent magnetism.Enter mixed state when magnetic field raises from null field, the magnetic flux density of sample core is lower than the magnetic flux density near the sample surfaces place, reduces magnetic field from High-Field and enters mixed state, and the distribution of magnetic flux density is then opposite.
When switching on, superconductor can produce self-fields, flux pinning also can hinder self-fields magnetic flux line turnover superconductor, at this moment the field flux distribution of superconductor inside also is uneven, and the unevenness that distributes just because of the magnet interior flux provides condition for the generation of superconducting tape macroscopic view current density.The vortex current of magnetic flux line is superimposed to have formed macroscopical current density.
Wherein J is macroscopical current density, and B is macroscopical magnetic induction density.
In superconductor, non-homogeneous magnetic flux grid is subjected to flux pinning force F
pWith magnetic flux driving force F
DFrom the angle of dynamic balance, if:
| F
D|≤| F
p| then magnetic flux does not move
| F
D|＞| F
p| then magnetic flux moves
Critical current density is to be defined in F
DWith F
pUnder the situation about equating, that is to say:
Following formula is in the critical state that does not move corresponding to non-homogeneous magnetic flux grid.
Consider Bean model, Bean model hypothesis pining force is only proportional with the first power of magnetic induction density, even:
F
p(x) ∝ B (x) formula (3)
Utilize formula (2) and formula (3) to obtain:
Following literal can be referring to Fig. 2.
In Fig. 2, thickness of sample is 2d, and externally-applied magnetic field is H, in the Z direction.
The obstructed excess current of superconductor after externally-applied magnetic field is removed, can be captured a part of magnetic flux, and the magnetic induction density that the B among Fig. 2 (x) is illustrated in X-direction distributes, and the absolute value of its slope equals μ
0J
cAbsolute value.The residual flux of the superconductor of unit length can be tried to achieve by following formula:
When the penetration field of externally-applied magnetic field above superconductor, lower limit of integral is 0, and integral result is μ
0J
cd
2, that is to say that the remnant field of superconductor is proportional to the critical current of superconductor.
Therefore the flux pinning ability of superconductor is strong more, and the magnetic flux of capturing is just many more, and meanwhile, the unevenness that interior flux distributes is just obvious more, and the crystal grain current density is big more.In fact, macroscopical current density of superconducting magnet is also relevant with the crystal boundary current density, but concerning the same a collection of band that same manufacturer produces, because the consistance of production technology, can think that the critical current of superconducting tape is that flux pinning ability with superconducting tape is directly proportional.The flux pinning ability can also show from the remnant field of superconducting tape, that is to say that superconducting tape captures the ability of magnetic flux in externally-applied magnetic field, and promptly the flux pinning ability is directly proportional with the remnant field of superconducting tape.
So superconducting tape is placed under the low temperature, about 77K, this moment, it was in superconducting state, at the uniform velocity entering magnetic field magnetizes, at this moment the size in magnetic field will surpass the magnetic field that penetrates of superconducting tape, and magnetic field can be produced by the coil of a pair of copper cash coiling, magnetic field decay rapidly beyond coil.The complete magnetized time of superconducting tape is very short, can ignore, so superconducting tape is not subjected to the influence of magnetizing time by the speed in magnetic field.When applying magnetic field, magnetic field should be perpendicular to superconducting tape.If magnetic field is too small, then the remanent magnetism of superconducting tape also can reduce accordingly, can not obtain the remanent magnetism amount of the maximum that superconducting tape captures, the accuracy that influence is measured.Externally-applied magnetic field should be steady magnetic field.Superconducting tape leaves after the externally-applied magnetic field, and by hall probe, hall probe is gathered the remnant field of superconducting tape.Remnant field is perpendicular to superconducting tape, and hall probe is placed perpendicular to superconducting tape.The copper coil in hall probe and generation magnetic field will have certain distance, this mainly is that the remanent magnetism of considering superconducting tape can be decayed after leaving magnetic field, in fact, for most of bands, the rate of decay is very fast, just can reach stationary value in one second, also consider to reduce the influence of background magnetic field in addition hall probe.In actual measurement, can adjust distance between hall probe and the field coil according to the movement velocity of superconducting tape, distance just can satisfy measurement requirement greater than 40 centimetres.This process just is equivalent to superconducting tape is measured later on by externally-applied magnetic field the process of the remnant field of superconducting tape.
Belt material of high temperature superconduct is an oxide ceramics, and in the process that processing generates, along with increasing of core number, sausage effect and bridging effect are difficult to avoid in the band, and this homogeneity to the long band of practicality can produce very big influence.The crystal defect difference of band each several part, the ability of capturing magnetic field is also different, so residual flux also can be different, can obtain the critical current uniformity of superconducting tape according to the ratio of superconducting tape remnant field.
This method provides a kind of way of quickly and easily superconducting tape being carried out quality testing.Utilize this way can detect part second-rate in the superconducting tape easily.
Description of drawings
Fig. 1 is the segmentation synoptic diagram of superconducting tape.
Fig. 2 is the synoptic diagram of the remnant field of superconducting tape.
Fig. 3 is principle of the invention figure.Among Fig. 3,1 is superconducting tape, and 2 is hall probe, and 3 is externally-applied magnetic field.
Fig. 4 is a specific embodiment of the invention synoptic diagram.Among Fig. 4,1 is superconducting tape, and 2 is hall probe, and 4 is provided magnet, and 5 is voltage table, and 6 is channel scanner, and 7 is computing machine, and 8 is radome, and 9 is liquid nitrogen, and 10 is direct supply, and 11 is shunt.
Fig. 5 is the relative position synoptic diagram of Hall plate array and superconducting tape, and 12 is Hall plate.
Fig. 6 is for measuring gained result's comparison diagram respectively with four leads method and the present invention.
Embodiment
The invention will be further described below in conjunction with the drawings and specific embodiments.
Fig. 3 a is for to apply externally-applied magnetic field to superconducting tape, and externally-applied magnetic field 3 requires the penetrate magnetic field of externally-applied magnetic field 3 greater than superconducting tape perpendicular to superconducting tape 1, and is direct current back of the body field.Externally-applied magnetic field 3 is produced by the provided magnet among Fig. 44, provided magnet 4 is the several-layer solenoid coil of a pair of copper cash coiling, provided magnet 4 is passed to direct current, produce D.C. magnetic field, the size of externally-applied magnetic field 3 just can satisfy the needs of measuring existing superconducting tape each several part critical current uniformity more than 400Gs.
Fig. 3 b is for measuring superconducting tape remanent magnetism, and the direction of superconducting tape remnant field is also perpendicular to superconducting tape 1, hall probe 2 place superconducting tape 1 directly over or under.In the measuring process, hall probe 2 remains unchanged with the distance of band.
In addition, consider the problem of electromagnetic compatibility, the magnetic field that provided magnet 4 is produced shields, and can reduce the influence of 3 pairs of hall probes 2 of background magnetic field so as far as possible.In order to reach the purpose of shielding, radome 8 is equipped with in provided magnet 4 outsides.Pass through for ease of superconducting tape, have seam on the radome 8, the direction of seam is consistent with magnetic field, and the non-cutting magnetic line of force is in order to avoid influence shield effectiveness.
With reference to Fig. 4, the function of each equipment and annexation are as follows among Fig. 4:
Among Fig. 4, superconducting tape 1 is successively by provided magnet 4 and hall probe 2, and after superconducting tape 1 magnetized in provided magnet 4, hall probe 2 was measured the remnant field of superconducting tape 1.Provided magnet 4 and hall probe 2, superconducting tape 1 all place liquid nitrogen 9.Power supply 10 is provided magnet 4 power supplies, magnetic field conductively-closed cover 8 shieldings that provided magnet 4 is produced.Shunt 11 will change magnitude of voltage into by the current value of provided magnet 4 so that measure.Hall probe 2 and shunt 11 are output as the input of channel scanner 6, and channel scanner 6 can be selected between the two at hall probe 2 and shunt 11.The output of channel scanner 6 is received in the input of voltage table 5, and after channel scanner 6 was selected, voltage table 5 was measured.Computing machine 7 control channel scanners 6 and read in the measured value of voltage table 5.
Measuring process is as follows:
1. utilize voltage table 5 to measure the magnitude of voltage of hall probes 2 under the situation that does not have the influence of superconducting tape remnant field, and with this measured value as zero point, when hall probe 2 is measured the superconducting tape remnant fields, from measured value, deduct this zero point.
2. provided magnet 4 is passed to direct current and produce the steady D.C. magnetic field, the size in magnetic field will surpass the magnetic field that penetrates of this superconducting tape 1, and the direction of background magnetic field 3 and superconducting tape 1 are mutually orthogonal.
3. in the measuring process, the intermittent motion of superconducting tape 1 between a pair of coil of provided magnet 4, the various piece of superconducting tape 1 is magnetized by the steady D.C. magnetic field that provided magnet 4 produces.The movement velocity size of superconducting tape 1 can be regulated as required voluntarily.
4. arrange a hall probe 2 in a side of provided magnet 4.Hall probe 2 just can satisfy the measurement needs apart from the distance of provided magnet 4 greater than 40 centimetres.The size of remnant field was more stable when superconducting tape 1 moved to hall probe 2 positions, and in addition in this position, the influence of 4 pairs of hall probes 2 of background magnetic field is also smaller.Superconducting tape 1 is successively by hall probe 2, and hall probe 2 is measured the remnant field of superconducting tape 1 each several part, and this moment, superconducting tape 1 was positioned at outside the provided magnet 4, and superconducting tape 1 space of living in does not have background magnetic field.
5. the output of using channel scanner 6 and voltage table 5 to measure hall probe 2.According to the output of voltage table 5, the remnant field of the superconducting tape 1 that calculating hall probe 2 collects.Magnetic field that hall probe 2 detects and its output voltage values are directly proportional, and scale-up factor can obtain from the manufacturer of hall probe 2, and the experimenter also can do experiment and oneself demarcate.The voltage that hall probe 2 is collected multiply by the value that scale-up factor just can obtain magnetic field.
6. repeat above-mentioned steps successively, obtain the remnant field of superconducting tape 1 each several part, just the remnant field of superconducting tape 1 is along the axial distribution of superconducting tape.The distribution vertically of the remnant field of superconducting tape 1 can be regarded as the critical current distribution vertically of superconducting tape 1, has so just finished all processes that the critical current uniformity of superconducting tape 1 is measured.
In above-mentioned measuring process, superconducting tape 1 be placed 77K or lower temperature environment, the also way of less expensive commonly used is to be placed in the liquid nitrogen environment.In order to measure the remnant field of superconducting tape 1, hall probe 2 also will be positioned in the liquid nitrogen environment.Consider the size of big or small direct ratio of the background magnetic field 3 that provided magnet 4 produces by the electric current of provided magnet, utilize shunt 11 and voltage table 5 to measure by behind the electric current of provided magnet 4, the electric current of crossing provided magnet 4 by monitor flows can calculate the size of the background magnetic field 3 that provided magnet 4 produced, so can monitor whether the size of background magnetic field 3 satisfies the needs of measuring.If the linearity of the hall probe that uses in the measuring process is fine, linear error is less than 0.1%, can directly utilize the distribution of the magnitude of voltage that hall probe measures to represent the distribution of the remnant field of superconducting tape so, promptly represent the critical flow homogeneity of superconducting tape each several part.
In experiment of the present invention, get one section superconducting tape 1, carry on the back field, band and magnetic field orthotropic with the speed of 10cm/sec by the direct current of 400Gs.Magnetic field is produced by provided magnet 4, central magnetic field 1000Gs during energising 33A, the long 15cm of magnet.
One section of superconducting tape 1 after the magnetization is passed through hall probe 2, and voltage table 5 is measured the output voltage of hall probes 2, multiply by scale-up factor, obtains the remnant field 30.12Gs of superconducting tape.Hall probe 2 can adopt the monolithic Hall plate, also can adopt the Hall plate array of being made up of a row Hall plate 12, and this method adopts a kind of mode in back, and the sensitizing range of every Hall plate is 100 μ m*100 μ m, and the spacing 600 μ m between the Hall plate can be referring to Fig. 5.Hall probe be placed on superconducting tape vertical directly over the 0.5mm place.The hall probe 2 that uses in this method not only can detect the ratio of superconducting tape elongatedness direction critical current, also can check superconducting tape to prolong the ratio of Width critical current.
The voltage of repeated acquisition hall probe 2 records the remnant field 31.36Gs of other one section superconducting tape, obtains the ratio 31.36/30.12 of two parts remnant field, is 1.04, just the ratio of their critical current.
Length direction along superconducting tape 1 is taken a sample successively, measures their remnant field.The ratio of superconducting tape remnant field can be used for representing the ratio of superconducting tape each several part critical current.
In the present embodiment, one section one section ground of superconducting tape is measured, the mass defect of superconducting tape can be detected easily.
The visible Fig. 6 of measurement data, Fig. 6 fundamental purpose is the validity of checking non-contact measurement method, and this is the silver-colored jacket superconducting tape of a segment length about 220cm, and transverse axis is a length, the left side longitudinal axis is the voltage of hall probe, and the right side longitudinal axis is the absolute value of critical current.The result who utilizes the method for the invention to measure represents with fine line that in the drawings the result that four leads method are measured represents with " ● ".Consider that the linearity of employed hall probe is fine in experiment, the magnitude of voltage of hall probe is not changed into the magnetic field value of superconducting tape.The distribution of superconducting tape each several part critical current is represented in the distribution of the voltage of hall probe among the figure, i.e. the homogeneity of critical current.
The present invention measures the ratio of the critical current of superconducting tape each several part, the just homogeneity of superconduction belt material critical current by the remnant field of measuring the superconducting tape each several part.The production of superconducting tape and use producer all can utilize the present invention to carry out the quality control of product.
Claims (9)
1. a method of measuring superconducting tape each several part critical current uniformity in the method, passes to direct current to provided magnet [4], produces steady D.C. magnetic field magnetic field [3] as a setting, and superconducting tape [1] is by background magnetic field [3]; In the time of outside superconducting tape [1] moves to background magnet [4], utilize hall probe [2] to measure the remnant field of superconducting tape [1], when measuring superconducting tape [1] remnant field, superconducting tape [1] space of living in does not have background magnetic field [3]; The ratio of superconducting tape [1] each several part remnant field equals the ratio of superconducting tape each several part critical current, and the homogeneity of superconduction belt material critical current just is characterized in that measuring process is as follows:
(1) utilize voltage table [5] to measure the magnitude of voltage of hall probe [2] under the situation that does not have the influence of superconducting tape remnant field as zero point, the measuring voltage value when hall probe [2] is measured the superconducting tape remnant field will deduct this zero point;
(2) provided magnet [4] is passed to direct current and produce magnetic field, superconducting tape [1] moves in as the gap between the several-layer solenoid coil of a pair of copper cash coiling of provided magnet [4], magnetizes; In the measuring process, the steady D.C. magnetic field that superconducting tape [1] each several part produces by provided magnet [4] successively;
(3) arrange hall probe [2] in a side of provided magnet [4], hall probe [2] is perpendicular to superconducting tape [1], and superconducting tape [1] is successively by hall probe [2], and hall probe [2] is measured the remnant field of superconducting tape [1] each several part;
(4) working voltage table [5] is measured the output of hall probe [2], according to the output of voltage table [5], and the remnant field of the superconducting tape [1] that calculating hall probe [2] collects;
(5) repeat above-mentioned steps successively, obtain the remnant field of superconducting tape [1] various piece, promptly the remnant field of superconducting tape [1] is along the axial distribution of superconducting tape; The remnant field distribution vertically of superconducting tape [1] can be regarded as the critical current distribution vertically of superconducting tape, has so just finished all processes that the critical current uniformity of superconducting tape is measured.
2. according to the method for the described measurement superconducting tape of claim 1 each several part critical current uniformity, it is characterized in that measuring speed can adjust according to the needs of self; Under the situation that does not change measuring speed, can improve the spatial accuracy of measurement by changing sample frequency.
3. according to the method for the described measurement superconducting tape of claim 1 each several part critical current uniformity, it is characterized in that described provided magnet [4] outside is equipped with radome [8], radome [8] has the seam consistent with magnetic direction.
4. according to the method for the described measurement superconducting tape of claim 1 each several part critical current uniformity, it is characterized in that superconducting tape [1] and hall probe [2] place 77K or lower temperature environment, both economical method is to place liquid nitrogen environment.
5. according to the method for the described measurement superconducting tape of claim 1 each several part critical current uniformity, it is characterized in that the size of described background magnetic field [3] will surpass the magnetic field that penetrates of superconducting tape [1], background magnetic field [3] is perpendicular to superconducting tape [1].
6. according to the method for the described measurement superconducting tape of claim 1 each several part critical current uniformity, it is characterized in that and can adjust distance between hall probe and the field coil according to the movement velocity of superconducting tape [1], distance just can satisfy measurement requirement greater than 40 centimetres.
7. according to the method for the described measurement superconducting tape of claim 1 each several part critical current uniformity, it is characterized in that utilizing shunt [11] and voltage table [5] to measure the electric current that passes through provided magnet [4], the electric current of crossing provided magnet [4] by monitor flows can monitor whether the size of background magnetic field [3] satisfies the needs of measuring.
8. according to the method for the described measurement superconducting tape of claim 1 each several part critical current uniformity, it is characterized in that if the linearity of the hall probe that uses in the measuring process [2] is fine, linear error is less than 0.1%, can directly utilize the distribution of the magnitude of voltage that hall probe [2] records to represent the distribution of the remnant field of superconducting tape, promptly represent the critical current uniformity of superconducting tape each several part.
9. according to the method for the described measurement superconducting tape of claim 1 each several part critical current uniformity, it is characterized in that hall probe [2] can adopt the monolithic Hall plate, also can adopt the Hall plate array of forming by a row Hall plate [12].
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB031497756A CN100359325C (en) | 2003-08-06 | 2003-08-06 | Method for measuring critical current homogenity of every portion for super conducting strip |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB031497756A CN100359325C (en) | 2003-08-06 | 2003-08-06 | Method for measuring critical current homogenity of every portion for super conducting strip |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1580803A CN1580803A (en) | 2005-02-16 |
| CN100359325C true CN100359325C (en) | 2008-01-02 |
Family
ID=34579665
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB031497756A Expired - Fee Related CN100359325C (en) | 2003-08-06 | 2003-08-06 | Method for measuring critical current homogenity of every portion for super conducting strip |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100359325C (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100582789C (en) * | 2005-06-17 | 2010-01-20 | 中国科学院电工研究所 | Compensation coil device for high temperature superconductive magnet test |
| CN1967281B (en) * | 2006-11-08 | 2011-05-18 | 中国科学院电工研究所 | Method and apparatus for measuring critical current uniformity of practical length YBCO high-temperature superconductive material |
| CN1963477B (en) * | 2006-11-08 | 2011-03-30 | 中国科学院电工研究所 | Method and apparatus for non-contact serial measurement of uniformity of n index of superconducting line/ strip steel rolled stock |
| CN101446612B (en) * | 2008-11-25 | 2011-09-14 | 中国电力科学研究院 | Measurement method of critical current properties of high-temperature superconducting tape |
| CN101788594B (en) * | 2010-01-08 | 2011-11-09 | 清华大学 | Non-contact type superconduction belt material critical current measuring device |
| CN101833027B (en) * | 2010-04-29 | 2011-11-09 | 清华大学 | Non-contact type superconducting tape current-carrying capacity measuring device |
| CN104483530B (en) * | 2014-12-24 | 2017-04-12 | 北京航空航天大学 | Method and device for measuring non-uniformity of critical current density of surface layer of high-temperature superconducting bulk material |
| CN107144802B (en) * | 2017-05-10 | 2019-04-16 | 清华大学深圳研究生院 | A kind of rapid survey superconducting thin film is averaged the method for critical current |
| CN108107385B (en) * | 2017-12-22 | 2020-07-24 | 武汉船用电力推进装置研究所（中国船舶重工集团公司第七一二研究所） | High-temperature superconducting magnet performance detection system and detection method |
| CN108152766B (en) * | 2018-01-04 | 2020-04-10 | 北京交通大学 | Superconducting tape magnetizing device |
| CN108279267A (en) * | 2018-02-11 | 2018-07-13 | 西南交通大学 | The continuous non-destructive testing device of Cable-in-conduit conductor local defect |
| CN108490066A (en) * | 2018-03-06 | 2018-09-04 | 西南交通大学 | The continuous non-destructive testing device of hyperconductive cable local defect |
| CN110873817A (en) * | 2018-08-30 | 2020-03-10 | 西部超导材料科技股份有限公司 | Method for guaranteeing accuracy and stability of critical current measurement system |
| CN110133561B (en) * | 2019-07-01 | 2021-02-05 | 合肥工业大学 | Main magnet uniformity detection and analysis device and method of MRI (magnetic resonance imaging) equipment |
| CN110579680B (en) * | 2019-08-07 | 2021-04-23 | 湖北工业大学 | Nondestructive testing device and method for superconducting cable |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4218633A1 (en) * | 1992-06-05 | 1993-12-09 | Siemens Ag | Critical current density measurer for high temp. superconducting films - contains direct magnetic field source and Hall probe device with several elements |
| JP2927537B2 (en) * | 1990-11-26 | 1999-07-28 | 株式会社チノー | Superconductivity test evaluation method |
| CN1580757A (en) * | 2003-08-05 | 2005-02-16 | 北京有色金属研究总院 | High temperature super conducting strip contactless nondestructive magnetic measuring method and device |
-
2003
- 2003-08-06 CN CNB031497756A patent/CN100359325C/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2927537B2 (en) * | 1990-11-26 | 1999-07-28 | 株式会社チノー | Superconductivity test evaluation method |
| DE4218633A1 (en) * | 1992-06-05 | 1993-12-09 | Siemens Ag | Critical current density measurer for high temp. superconducting films - contains direct magnetic field source and Hall probe device with several elements |
| CN1580757A (en) * | 2003-08-05 | 2005-02-16 | 北京有色金属研究总院 | High temperature super conducting strip contactless nondestructive magnetic measuring method and device |
Non-Patent Citations (1)
| Title |
|---|
| 感应法测量高温超导筒临界电流研究. 何砚发，宗曦华，孙晶，王金星.低温物理学报，第24卷第1期. 2002 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1580803A (en) | 2005-02-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN100359325C (en) | Method for measuring critical current homogenity of every portion for super conducting strip | |
| EP0898706B1 (en) | Device for highly sensitive magnetic detection of analytes | |
| EP0874246B1 (en) | Method and apparatus for contactless longitudinal and vertical homogeneity measurements of the critical current density jc in superconducting tape | |
| DE1473696A1 (en) | Method and device for static and dynamic material testing by means of magnetic feedback | |
| CN1967281B (en) | Method and apparatus for measuring critical current uniformity of practical length YBCO high-temperature superconductive material | |
| WO2015028569A1 (en) | Method and apparatus for analysing a sample volume comprising magnetic particles | |
| Tsukamoto et al. | Development of eddy current testing system using HTS-SQUID on a hand cart for detection of fatigue cracks of steel plate used in expressways | |
| CN113203792A (en) | TMR multi-array deep defect weak magnetic detection device | |
| Hartmann et al. | A system for measurement of AC Barkhausen noise in electrical steels | |
| DE112020007090T5 (en) | MAGNETIC PARTICLE IMAGING DEVICE | |
| Liu et al. | Stress measurement of ferromagnetic materials using hybrid magnetic sensing | |
| Liang et al. | A real time high sensitivity high spatial resolution quantum well hall effect magnetovision camera | |
| DE1573837C3 (en) | Testing device for non-destructive testing of magnetizable materials | |
| Fryskowski | Experimental evaluation of magnetic anisotropy in electrical steel sheets | |
| Charubin et al. | Mobile ferrograph system for ultrahigh permeability alloys | |
| Trisnanto et al. | Long-range stray field mapping of statically magnetized nanoparticles using magnetoresistive sensor | |
| Tumański | The application of permalloy magnetoresistive sensors for nondestructive testing of electrical steel sheets | |
| JP2912003B2 (en) | Method for measuring magnetic properties of superconductors | |
| EP2023131B1 (en) | Method and device for interference-free testing of an object containing material fractions which are magnetic and conductive | |
| Beckley | Continuous power loss measurement with and against the rolling direction of electrical steel strip using nonenwrapping magnetisers | |
| Chankji et al. | A method for mapping magnetic fields generated by current coils | |
| DE2643664C2 (en) | Device for the localization of substances in a body with a weakly magnetic base material | |
| JPH04218764A (en) | Detecting device of deterioration and damage of metal material | |
| Morad et al. | The design and use of secondary shielding in MRI systems-experiments from 4 years of operation | |
| Charubin et al. | Automatic measurement station for ferrite materials testing |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20080102 Termination date: 20150806 |
|
| EXPY | Termination of patent right or utility model |