JPS60764B2 - superconducting coil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a superconducting coil, and more particularly to a superconducting coil in which, for example, a plurality of superconducting partial coils are housed in a cryogenic container containing a cooling medium.

Generally, superconducting coils are often used as devices for generating high magnetic fields, but unlike ordinary electromagnets, superconducting coils need to be cooled to extremely low temperatures, primarily to the temperature of liquid helium.

FIG. 1 is a partially cutaway perspective view of a conventional pancake-shaped superconducting coil.

This superconducting coil 5 has a structure in which a plurality of pancake coils, each of which is a superconducting wire 1 wound with an inter-turn smoother 3 interposed therebetween, are fixed in a cumulus manner within a winding frame 2 via an interlayer smoother 4. The superconducting wire 1 is electrically insulated both between turns and between layers by an interturn spacer 3 and an interlayer spacer 4, and the interlayer spacer 4 forms a gap 41 through which a cooling medium such as liquid helium flows. This gap 41 not only allows air bubbles of the cooling medium generated on the surface of the superconducting wire 1 to escape, but also has the role of replenishing the cooling medium. Figure 2 shows the excitation protection circuit for the superconducting coil.

The superconducting coil 5 corresponds to the pancake-shaped superconducting coil 50 shown in FIG. With this excitation protection circuit, the superconducting coil 5
is immersed in a low temperature container 7 in which a cooling medium 6 is stored,
With the switch 8 closed, the magnet is excited to the rated operating current L by the excitation power source 9. By the way, during operation of the superconducting coil 5, the superconducting coil 5 may be quenched (superconducting breakdown in which the original superconducting state cannot be restored).

Note that the occurrence of quench in the superconducting coil 5 is normally detected when the resistive voltage generated in the superconducting coil 5 reaches a predetermined value, but it can also be detected by measuring the temperature rise. In some cases.

When a quench occurs in the superconducting coil 5, it is necessary to rapidly remove the magnetic energy stored in the superconducting coil 5 and suppress the temperature rise of the superconducting coil 5 within a certain limit (about room temperature).

The excitation protection circuit shown in FIG. 2 is widely used for protection when quench occurs in the superconducting coil 5, and a protective resistor 10 is connected in parallel with the superconducting coil 5 to provide protection when quench occurs. In this case, the switch 8 is opened and the magnetic energy stored in the superconducting coil 5 is rapidly absorbed by one protective resistor. In this way,
Most of the magnetic energy stored in the superconducting coil 5 is consumed by the protective resistor 10, and some of the magnetic energy is consumed in the cooling medium, so the superconducting coil 5 does not burn out and the cooling medium is not consumed. It becomes less.

In such a conventional pancake-shaped superconducting coil 50', quench begins to occur at a portion of the superconducting wire 1 of the pancake coil 101, for example.

However, over time, the quenched portion not only propagates to other parts of the superconducting wire 1 of the same pancake coil 101, but also spreads to other parts of the superconducting wire 1 adjacent to the pancake coil 101 due to evaporation of the cooling medium due to the quench.
And it spread rapidly to 102 as well. The speed at which the quench propagates to adjacent pancake coils is farther than the speed at which the quench propagates through the superconducting wire of the same pancake coil. Such a conventional pancake-shaped superconducting coil 5...
．． Let's calculate the energy consumption in the superconducting coil when a quench occurs in a river.

The resistance Rc(t) when one pancake coil of the pancake-shaped superconducting coil 50 is quenched is Rc,(t)
=rct . . . { Assume that it increases linearly as shown in 11.

rc (Qnos) can be said to be the resistance increase rate. In the subordinate pancake-type superconducting coil 50, this holds true even if it is assumed that each pancake coil starts quenching at the same time, so the resistance of the pancake-type superconducting coil 50 having n pancake coils is Rc(t)= nrct
...It is represented by """river"" [2}.

t=0 is the time when the quench starts, and if the switch 8 in FIG. 2 is opened at the same time as the quench, the superconducting coil 5
The current lo flowing through the protective resistor Rp attenuates as it flows through the protective resistor Rp. The circuit equation at this time is L group 10 (RC+mCt
)i=. ...(3}(Initial condition: when t=0, i=lo
), and the energy consumed by the superconducting coil 5 is W
It becomes n=nrCt no hair dt---...-■.

Here, L is the inductance of the superconducting coil 5.
Here, by solving the above equation (3), i = 10exp [1 (wave pt + nrct2)/phantom].
・．． ...(5) is obtained, so Wn = Body, Zero - ■ Earth. eXp[R2P/nLrC]. E
MC (by vessel)...becomes side nrc.

k=R2c/Lrc・・・・・・・・・・・・
...[If we set it as 7', then n=Wn/(Kyo L1-tei)
---...-----...-■The energy consumption rate in the superconducting coil is wn=1-2 k/n. e×p [k/n]
・Er has (ノk/n)...■.

Here, “EMC (Gen Sannobishi e t2dt…
...00 indicates an error function.

A concrete numerical calculation will be made regarding the conventional pancake-shaped superconducting coil 50.

For example, if inductance L = 10 plates, superconducting coil resistance increase rate r = 0.010/s, protective resistance Rp = 10, and number of pancake coils n = 4, k = 1, Ehc (0
．． 5)=0.4249, so the energy consumption rate is 4=0.4544. Thus, in the conventional pancake-shaped superconducting coil 50, the energy consumption rate is 45% under the above conditions, but this value is not small and further improvement is desired.

Therefore, the main object of the present invention is to provide a superconducting coil that can reduce energy consumption when, for example, a pancake-shaped superconducting coil quenches.

In summary, this invention provides a partition plate between a plurality of superconducting partial coils in a low-temperature container to make each superconducting partial coil spatially independent, and further provides good heat conduction at the connecting portion between each superconducting partial coil. This is a superconducting coil in which block members having special characteristics are brought into contact with each other, whereby quench generated in one superconducting partial coil does not propagate to other superconducting portions, thus reducing consumption of cooling medium.

The above objects and other objects and features of the invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 3 is a partially cutaway perspective view showing one embodiment of the present invention.

In the configuration, adjacent pancake coils (which will be referred to as superconducting partial coils) 100, 101, 10
A partition plate 11 is provided between the two superconducting partial coils, and each superconducting partial coil forms an independent space with respect to the cooling medium. By providing this partition plate 11, when a certain superconducting partial coil, for example 101, quenches and the cooling medium evaporates,
It is possible to prevent the quench from immediately propagating to the adjacent superconducting partial coils 100 and 102. In this way, in the pancake-shaped superconducting coil 51 of the present invention, quenching can be limited to some superconducting partial coils, but the energy consumption rate in this case is calculated as follows.

There is only one superconducting partial coil to quench, so n=1
The other conditions are the conventional pancake type superconducting coil 5
Assuming that Ehc{1-=0.1394, the energy consumption rate decreases to 0.2421, that is, 24%. Although the partition plate 11 in the low temperature container in this invention does not need to have complete airtightness,
It is desirable to have airtightness against a surface pressure of about lk9/c and strength to withstand a differential pressure of this order.

Further, the material of the partition plate 11 may be any material such as an insulator, stainless steel, copper, etc., or may be a composite material having a metal surface treated with insulation. However, in a superconducting coil placed in an alternating magnetic field, it is desirable to use an insulating partition plate. Due to the presence of the cutting plate 11 in this invention, even if one superconducting partial coil is quenched and the cooling medium evaporates, the quench remains only in that superconducting partial coil, but the effect is not necessarily complete. do not have. This is because the quench propagates along the superconducting wire of the quenched superconducting partial coil, and the adjacent superconducting partial coil may be quenched through the connection portion with the adjacent superconducting partial coil. It is a figure which shows the connection part 13 between pancake coils.

Two superconducting wires 1 are overlapped and the contacting part is made of Pb-S.
Connected with solder such as n. However, in a pancake-type superconducting coil having such a connection portion 13, it is very difficult to prevent quench propagation from propagating from one superconducting partial coil to another superconducting partial coil. FIG. 5 shows an embodiment of the connecting part which eliminates the above-mentioned drawbacks.

In structure, the connecting part 14 has a structure in which metal blocks 15 (for example, copper) are brought into contact with both sides of the connecting part 13 shown in FIG. In this way, the metal block 15 is attached to the connection part.
By providing this, it can be expected that the heat capacity of the metal block 15 will suppress the temperature rise due to quench occurring in one superconducting wire, and the quench will not propagate to other superconducting wires. Note that the contact between the metal block 16 and the superconducting wire 1 may be made by soldering or by mechanical tightening.Furthermore, this contact portion 14 does not necessarily have to be in contact with the cooling medium; The contact has the effect of reducing the temperature rise of the connecting portion 14.Also, the connecting portion 14 of this embodiment has one metal block 15 on each side of the connected superconducting wire 1, One metal block 15 may be provided on either side, or the metal block 15 may be placed between the superconducting wires 1 for connection.In this way, the partition plate 11 may be placed between the superconducting partial coils. In a pancake-type superconducting coil in which a superconducting partial coil indirect twill portion 14 having a metal block 15 is provided, the quench generated in one superconducting partial coil can be completely limited to only that superconducting partial coil. Therefore, the energy consumed by the superconducting coil during quenching can be made considerably smaller than that of conventional superconducting coils.

In the above description, a pancake-shaped superconducting coil was used as an example of the superconducting coil, but the present invention is not limited to the pancake-shaped superconducting coil.

FIG. 6 is a sectional view showing another embodiment of the invention.

This is a superconducting coil in which a solenoid coil 52 in which a superconducting wire 1 is wound through a spacer 3 between turns is housed in a low temperature container 7, and a partition plate 11 is provided between each of the one-layer solenoid coils 500 to 503, which are superconducting partial coils. . Due to this partition plate 11, even if the superconducting partial coil, for example, the single-layer solenoid coil 500, is quenched, the cooling medium between the two partition plates 11, 11 only evaporates.
Therefore, the speed at which the quench propagates to other superconducting partial coils can be slowed down, and the energy consumed in the superconducting coils can be reduced. In addition, if the connecting portions between the partial coils are made into the connecting portions 14 shown in FIG. 5, it is even more effective in reducing energy consumption.

In addition, in FIG. 6, illustration of the coil winding frame and interlayer smoother is omitted.

Furthermore, in the invention shown in FIGS. 3 and 6, one pancake coil and one-layer solenoid coil are respectively used as partial coils, but it is also possible to use a plurality of pancake coils and a multi-layer solenoid coil as partial coils. Of course. As detailed above, the present invention provides a partition plate between a plurality of superconducting partial coils to make each superconducting partial coil spatially independent,
Furthermore, since a metal block is brought into contact with the connecting portion between each superconducting partial coil, the quench generated in one superconducting partial coil is prevented from propagating to other superconducting partial coils, thereby further reducing energy consumption in the superconducting coil. have

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway view of a conventional pancake-shaped superconducting coil. FIG. 2 is a circuit diagram of a superconducting coil excitation protection device. FIG. 3 is a partially cutaway view of a pancake-shaped superconducting coil according to an embodiment of the present invention. FIG. 4 shows a conventional connection part of a superconducting coil. FIG. 5 shows a connecting portion which is an embodiment of the present invention. FIG. 6 is a sectional view of a superconducting solenoid coil according to another embodiment of the present invention. In the figure,
The same reference numerals indicate the same or corresponding parts, and 100
500 to 503 are superconducting partial coils, 51 is a pancake-shaped superconducting coil, and 52 is a superconducting solenoid coil. 7 is a low-temperature container, 11 is a partition plate, 14 is a connecting portion, and 15 is a metal block. Figure 6 Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. A low-temperature container containing a cooling medium, a plurality of superconducting partial coils housed in the low-temperature container, a connection portion connecting each of the superconducting partial coils, and a good heat source brought into contact with the connection portion. A superconducting coil comprising: a block member having conductive properties; and a partition plate disposed between each of the superconducting partial coils to make the superconducting partial coils spatially independent. 2. The superconducting coil according to claim 1, wherein said block member is made of metal.