JPS6220205A - Manufacture of force cooled type superconductor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing a forced cooling type superconductor having a flow path for a cryogen (generally liquid helium) in the superconductor, and more specifically, The present invention relates to an effective method for preventing coupling current generated between wires.

[Conventional technology and its problems]

The four forced cooling type superconductors that flow cryogen inside the conductor include
■A superconducting wire wrapped around the outer circumference of a cooling pipe,
■Superconducting wire is buried inside the cooling pipe! -2
There are two types. Among them, the four superconducting bodies with structure ■ are:
When used in a pulsed magnetic field, the cooling pipe is generally made of high-resistance materials such as stainless steel or cypronickel to reduce eddy current loss that occurs in the cooling pipe due to sudden magnetic field fluctuations.

However, the four superconducting bodies using high-resistance cooling pipes
The drawback is that the alternating current loss in the conductor under a pulsed magnetic field is large, and the temperature of the conductor rises, causing a transition from superconductivity to normal conductivity (so-called quenching), similar to when eddy current loss occurs in a pipe. The cause of this is that coupling loss occurs between the superconducting wires via the cooling pipe.

Therefore, an object of the present invention is to prevent the temperature rise of the conductor due to the coupling current.

[Failure to solve the problem]

In order to achieve the above object, in this invention, an insulating thin film layer is formed in advance by blowing a gas made of fine ceramic powder into plasma on the outer surface of the cooling pipe around which the superconducting wire is wound. It is.

FIG. 1 is a cross-sectional view showing an example of four superconducting bodies obtained by this method, in which reference numeral 1 denotes a cooling pipe made of copper, stainless steel, or quibronickel, through which a cryogen is passed. be done.

2 is At203, BN% SiC% MgOXZr
An insulating thin film layer 3 is formed on the surface of the pipe 1 by spraying a ceramic plasma gas such as O2 or TiC, and numeral 3 indicates a superconducting wire. In addition, cooling pipe 1
In addition to pipes with a circular cross section, pipes with a square cross section are sometimes used.

The insulating thin film layer 2 has sufficient adhesion strength because high-energy particles sometimes diffuse inside the surface layer of the pipe 1 when plasma-like gas is sprayed, and the mechanical strength of the insulating thin film layer 2 is ensured by winding the superconducting wire 3. There is no need to worry about the strength decreasing significantly. Therefore, the wire winding maintains good electrical insulation afterward, and this blocks the movement of current between the pipe 1 and the wire 3, resulting in coupling loss that occurs even under sudden magnetic field fluctuations. No current flows. Therefore, the temperature rise of the conductor is also suppressed, and the performance of the superconducting device formed by the conductor is fully brought out.

Although ceramic is an insulator and does not have excellent thermal conductivity, coupling current can be prevented if the film is several to ten micrometers thick, and since a very thin film like this is sufficient, it can be used from superconducting wires to There is no adverse effect on heat transfer to the cooling pipes.

〔Example〕

Examples of the present invention and experiments conducted to confirm the effects are described below.

6. An alumina insulating layer with a thickness of 5 μm was formed on the surface of a stainless steel pipe with an outer diameter of 4.0 yφ and an inner diameter of 3.0 yφ by plasma spraying, and a superconducting wire of 81 Mφ was wound along the outer circumference ζ:〇. We fabricated four superconducting bodies with a diameter of 2 mm. Then, as shown in FIG. 2, this conductor 4 is wound around a coil bobbin 5, and the outer diameter is D-207 mm, the inner diameter is d-50 mm, and the height H=
125 mm, number of winding turns 216 turns, critical current 960
A-2T (Tesla), inductance L = 2.64mH
A superconducting magnet was manufactured. In the figure, reference numeral 6 indicates a current lead wire, 7 indicates an electrode, and 8.9 indicates a refrigerant inlet/outlet of a cooling pipe.

After cooling the magnet by passing cryogen through pipe 1, a pulse current is applied from a 100OA power supply to the target specification 1.
．． The magnetic field was set up at 8T/sec up to 6T. The excitation voltage at this time is 13.2V.

Next, hold 100OA-1,6T for 1 second, then -
Although it was demagnetized at 13.2V, the magnet operated normally without quenching. For comparison, when a magnet with the same target specifications using four superconducting bodies without an insulating film on the outside of the cooling pipe was tested under the same conditions, the conductor temperature rose and quenched.

〔effect〕

As described above, according to the present invention, the cooling pipe can be
A thin electrically insulating layer is formed between the superconducting wire and the cooling pipe by spraying a ceramic plasma gas on the surface of the product in advance, which is then wound around the superconducting wire, so that a product with stable performance that does not cause chi is obtained.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an example of four superconducting bodies obtained by the present invention, and Fig. 2 is a cross-sectional view of a superconducting magnet produced in order to test the performance of the four superconducting bodies obtained by the method of the embodiment. A front view of the fracture is shown in Figure 1. 1...Cooling pipe, 2...Insulating thin film layer, 3...Superconducting strand patent applicant Sumitomo Electric Industries, Ltd. Agent: Sickle
1) Sentence 2

Claims (1)

[Claims] A forced cooling type superconductor characterized by forming an insulating thin film layer by spraying a gas containing fine ceramic powder in the form of plasma on the outer surface of a cooling pipe around which the superconducting wire is wound (before winding the superconducting wire). How the body is manufactured.