CN102568705A - Producing method of niobium three stannum cable-in-conduit conductors of large superconducting magnets - Google Patents

Abstract

The invention discloses a producing method of niobium three stannum cable-in-conduit conductors of large superconducting magnets, which includes steps of conducting cleaning, pressing leakage detecting and flaw detection on a stainless steel tube serving as the conductor armor; welding the stainless steel tube into a homogeneous tube, and detecting probable flaws of welding beads; enabling superconducting cables of multistage stranded cables to penetrate into the stainless armor; conducting hole shrinkage and molding on the conductor by using multistage rollers, controlling the voidage inside the conductor within about 30%, and producing the conductor into a rectangle conductor; and pre-bending the molded rectangle conductor, conducting pressing leakage detecting and flaw detection of the whole to produce the niobium three stannum cable-in-conduit conductors. By means of the producing method, the niobium three stannum cable-in-conduit conductors can decrease and even eliminate the degradation of conductor superconducting performance caused by the electric magnetic circulation.

Description

A kind of manufacture method of niobium three tin-tube inner cable conductors of large-scale superconducting magnet

Technical field

The present invention relates generally to the superconducting magnet technical field, is specifically related to a kind of manufacture method of niobium three tin-tube inner cable conductors of large-scale superconducting magnet.

Background technology

Pipe inner cable conductor is that niobium titanium or niobium three tin superconducting wires are become hyperconductive cable through multistage twisting, hyperconductive cable is penetrated in the stainless-steel pipe again, through undergauge, moulding, is made into pipe inner cable conductor, adopts supercritical helium or superfluid helium to compel the stream cooling.This method has improved the contact area of superconducting line and helium; Improved heat transfer condition; And make pipe inner cable conductor have characteristics such as good self-supporting, lower A.C.power loss, required coolant are few, safe and reliable to operation, performance height; Become the first-selected conductor of large-scale superconducting magnet, successful is applied in the middle of tokamak device, stellarator device and the large-scale high field super magnet.Yet; In the process that the niobium three tin-tube inner cable conductors of international thermonuclear fusion device ITER are researched and developed, find in recent years; After repeatedly electromagnetism circulated, irreversible performance degradation appearred in the superconductivity of niobium three tin superconducting conductors, and this will directly have influence on long-term stability operation of large-scale superconducting magnet.

Find through a large amount of experiments; Because niobium three tin materials after the heat treatment have very strong fragility; Lorentz force in the electromagnetism circulation makes superconducting conductor produce very big horizontal magnetic pressure; Cause the internal structure of niobium three tin materials that variation has taken place, produced trickle crackle in the part, thereby caused the degeneration of superconducting conductor performance.Therefore can not directly adopt the design concept of original niobium titanium pipe inner cable conductor; Need to improve again the pipe inner cable conductor of employing niobium three tin superconductors and the design of hyperconductive cable; Make it to have good self-supporting, minimizing even elimination are because the performance degradation that the electromagnetism circulation causes.

Summary of the invention

Be the irreversible performance degenerate problem that niobium three tin-tube inner cable conductors in the solution prior art occur after repeatedly electromagnetism circulates, producing can the large-scale superconducting magnet of moving steady in a long-term.

The present invention provides a kind of manufacture method of niobium three tin-tube inner cable conductors of large-scale superconducting magnet; Multistage stranded cable niobium three tin hyperconductive cables, poling, the undergauge of adopt optimizing, be molded into the rectangle conductor; And reduce the voidage of conductor; Making to manage between the inner strand of inner cable conductor to have better self-supporting, reduces because displacement and the distortion that horizontal magnetic pressure causes.

The niobium three tin-tube inner cable conductors of large-scale superconducting magnet provided by the invention; Also will adopt the armor of improved 316LN stainless steel tube as conductor; Material after the improvement has the Thermal Contraction Coefficient that more approaches niobium three tin superconducting wires at low temperatures; The strain of the hyperconductive cable that reduces to produce owing to armor is different with the hyperconductive cable Thermal Contraction Coefficient improves the performance of superconducting magnet.

The present invention adopts following technical scheme:

The manufacture method of the niobium three tin-tube inner cable conductors of large-scale superconducting magnet is characterized in that may further comprise the steps:

(1) adopts improved 316LN stainless steel tube, steel pipe is cleaned, guarantee no grease, dust or other finely ground particles in the steel pipe; And every steel pipe carried out eddy current test, ultrasonic inspection, suppresses with vacuum and take out leakage, require leak rate≤10 ^-10Pam ³/ s.

(2) with stainless steel tube butt welding, be welded into a homogeneous tube, postwelding inspection weld seam surfaces externally and internally does not allow depression, burr, overlap, outer lug boss≤0.1mm in the weld seam; The per pass weld seam is carried out that surface colour inspection, endoscope are inspected, X-ray and ultrasonic detection, beats withstand voltage and vacuum leak hunting, and the per pass weld seam is tried to lead to drift.

(3) make and to wear cable joint reliably, niobium three tin hyperconductive cables and the steel cable of multistage stranded cable coupled together, hyperconductive cable is penetrated in the stainless steel tube, monitor pulling force and poling speed in real time, guarantee that cable can smooth poling, the while is not damaged cable surface.

(4) utilize multistage pair of rollers conductor to carry out undergauge and moulding, the stainless steel tube with circle carries out undergauge to a certain degree earlier, is pressed into rectangular conductor again, and the voidage in the conductor is controlled at 29-30%.30% voidage had both guaranteed to have in the conductor enough spaces through liquid helium, had guaranteed the excellent support between strand in the conductor again; Electromagnetic pressure when rectangular conductor structure has reduced the superconducting magnet energising in the conductor has reduced displacement and the deformation of the superconduction strand that horizontal magnetic pressure that electromagnetic force produces causes.

(5) the rectangle conductor after the moulding is carried out pre-bending, receive on reel, and integral body suppresses 3MPa and hunt leak, make leak rate less than 1 * 10 ^-10Pam ³/ S is made into niobium three tin-tube inner cable conductors.

Conductor armor of the present invention adopts improved 316LN stainless steel tube; The content of control carbon and nitrogen, and change and limit other constituent contents, the stainless steel material after the improvement has higher intensity at low temperatures; Has the Thermal Contraction Coefficient that more approaches niobium three tin superconducting wires simultaneously; The strain of the hyperconductive cable that reduces to produce owing to armor is different with the hyperconductive cable Thermal Contraction Coefficient improves the performance of superconducting magnet, and the chemical composition of 316LN is required as follows:

Composition (wt%)

C

Si

Mn

P

S

Cr

Ni

Mo

N

Co

Improved 316LN

<0.02 target <0.015

< 0.75

< 2.0

< 0.045

< 0.03

16.0- 18.0

11.0- 14.0

2.0- 3.0

0.14-0.18

<0.05

The present invention adopt dyeing, ultrasonic, x-ray, in several different methods such as peep stainless steel tube and weld seam detected a flaw, guarantee the sealing property of superconducting conductor.

The present invention adopts the multistage stranded cable niobium three tin hyperconductive cables of optimization, in preceding what sub-cable, adopts long torque, in the afterbody, adopts short torque, and making can have better contact and support between the inner strand of hyperconductive cable.

The present invention penetrates hyperconductive cable in the stainless steel tube; Utilize multistage pair of rollers steel pipe to carry out undergauge and moulding; Make the inner voidage of conductor reach 29%-30%, make superconducting conductor be shaped to the rectangle conductor simultaneously, guarantee in the magnet High-Field place magnetic field B and operating current I amass and the ratio of conductor broadside width W less than 11Mpa; When reducing superconducting magnet work, because the displacement and the deformation of the superconduction strand that the horizontal magnetic pressure that Lorentz force produces causes.Conductor after the moulding is carried out pre-bending, and carry out integral body and suppress 3MPa and hunt leak, make leak rate less than 1 * 10 ^-10Pam ³/ S.

Beneficial effect of the present invention:

(1) the multistage stranded cable niobium three tin hyperconductive cables of the present invention through adopt optimizing, reduce the voidage of conductor and be made into the rectangle conductor; Making to manage between the inner strand of inner cable conductor to have better self-supporting, has reduced because the displacement and the distortion of the superconduction strand that horizontal magnetic pressure causes.

(2) the present invention is through adopting the armor of improved 316LN stainless steel tube as conductor; Make armor have the Thermal Contraction Coefficient that more approaches niobium three tin superconducting wires at low temperatures; The strain of the hyperconductive cable that reduces to produce owing to armor is different with the hyperconductive cable Thermal Contraction Coefficient has improved the performance of superconducting magnet.

(3) the present invention detects the defective that stainless steel tube and weld seam possibly exist through the whole bag of tricks, and the conductor after the moulding is carried out integral body suppress leak detection, has guaranteed the sealing property of superconducting magnet.

(4) the present invention is through the niobium three tin-tube inner cable conductors of this method making; Improved the self-supporting between strand in the conductor; Can effectively reduce even eliminate because the performance degradation problem that the electromagnetism circulation causes; Produce can operation steady in a long-term large-scale superconducting magnet, in the middle of the test magnet that is applied to the outer superconducting magnet of 40T hybrid magnet that the manufacture method of these niobium three tin-tube inner cable conductors is successful.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Embodiment

Embodiment 1:The manufacture method of the niobium three tin-tube inner cable conductors of large-scale superconducting magnet may further comprise the steps:

(1) stainless steel tube as the conductor armor is suppressed, hunted leak and detects a flaw;

(2) stainless steel tube is welded into a homogeneous tube, and the possible defective of butt welded seam detects;

(3) hyperconductive cable with multistage stranded cable penetrates in the stainless steel armor;

(4) utilize multistage pair of rollers conductor to carry out undergauge and moulding, the voidage in the conductor is controlled at 29-30%, and conductor is made into the rectangle conductor;

(5) the rectangle conductor after the moulding is carried out pre-bending, and carry out integral body and suppress leak detection, be made into niobium three tin-tube inner cable conductors.

Embodiment 2:The manufacture method of the niobium three tin-tube inner cable conductors of large-scale superconducting magnet may further comprise the steps: stainless steel tube 1 is welded into a homogeneous tube, and the defective that stainless steel tube and weld seam possibly exist is detected a flaw and suppressed leak detection; The hyperconductive cable 2 of multistage stranded cable is penetrated in the stainless steel armor 1, carry out undergauge and moulding through multistage roller 3 again, the voidage in the conductor is controlled at about 30%, and conductor is made into rectangular pipe inner cable conductor 4; Conductor after the moulding 4 is carried out pre-bending, be fixed on the wire winding tube 5, and carry out integral body and suppress leak detection, be made into niobium three tin-tube inner cable conductors.

Claims (1)

1. the manufacture method of the niobium three tin-tube inner cable conductors of a large-scale superconducting magnet is characterized in that may further comprise the steps:

(1) stainless steel tube of conductor armor is suppressed, hunted leak and detects a flaw;

(2) stainless steel tube is welded into a homogeneous tube, and the possible defective of butt welded seam detects;

(3) hyperconductive cable with multistage stranded cable penetrates in the stainless steel armor;

(4) utilize multistage pair of rollers conductor to carry out undergauge and moulding, the voidage in the conductor is controlled at 29-30%, and conductor is made into the rectangle conductor;

(5) the rectangle conductor after the moulding is carried out pre-bending, and carry out integral body and suppress leak detection, be made into niobium three tin-tube inner cable conductors.

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