JPH02252214A - Cooling method for forcible cooling type superconducting coil - Google Patents

Abstract

PURPOSE:To efficiently cool a superconducting coil by injecting refrigerant helium gas when the temperature of the superconducting coil is high, externally precooling the coil, and feeding the gas into the the coil to cool it when the temperature of the coil drops. CONSTITUTION:When the temperature of a superconducting coil 21 is high, a helium injection valve 29 is opened to inject refrigerant helium gas from a refrigerator from the valve 29, and the coil 21 is externally precooled. The injected gas is sucked from a suction valve 31, and returned to the refrigerator. When the temperature of the coil 21 is reduced by precooling, the valves 29, 31 are closed, and the gas is fed in the coil 21. In this case, since the coil 21 is precooled, the gas is smoothly fed into the coil 21. Remaining gas in a vacuum tank 12 is discharged by a vacuum pump 14. Thus, the desired coil can be efficiently cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for cooling a forced cooling type (caple-in-conduit type) superconducting coil used in the field of nuclear fusion and the like.

<Conventional technology> Superconducting coils used for plasma confinement in nuclear fusion reactors are used under extremely strong magnetic fields, so in order to withstand the electromagnetic force, a pipe-shaped conduit material is required. The forced cooling type (caple-in-conduit type), which consists of superconducting wires (see Figure 3) stacked in a coil shape, is used (see Figure 4). has been done.

As shown in FIG. 7, this type of cooling method for the superconducting coil 1 conventionally involves supercritical pressure cryogenic energy sent from a refrigerator (not shown) through a cooling passage 20 in a vacuum chamber 4. After the refrigerant helium gas was further cooled by the heat exchanger 3 in the liquid helium boiler 3, it was forced to flow into the superconducting coil 1 through the cooling passage 2b, and the superconducting coil 1 was forcibly cooled by the refrigerant helium gas.

In addition, as another cooling method, a copper plate fin is inserted between the layers of the superconducting coil, and a cooling pipe is provided in this fin to bypass the cooling piping, and cooling is performed through this fin for initial precooling. (For example, the Proceedings of the 37th Society of Cryogenic Engineering (P2O)).

<Problems to be Solved by the Invention> However, in the former case, since the temperature of the superconducting coil 1 is high during precooling (initially room temperature), the temperature of the refrigerant helium gas absorbs heat and becomes high, resulting in increased viscosity. Then, the pressure loss of the refrigerant helium gas within the superconducting coil 1 became large, and as a result, the flow rate of the refrigerant helium gas became small, and precooling took a long time.

In the latter case, the pre-cooling time can be shortened, but since the cooling device is used in an alternating current magnetic field, the copper plate fins generate extra eddy currents, reducing the stability of the superconducting coil 1. was there.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a method for cooling a forced-cooling superconducting coil that can efficiently precool a superconducting coil in a short time without reducing the stability of the superconducting coil.

Means for Solving the Problem> The technical means of the present invention for solving this problem is to cool the forcibly cooled superconducting coil 2 through the cooling channel in the vacuum chamber 12.
1 in which the coil 21 is forcibly cooled by flowing a refrigerant through the superconducting coil 21, the ejected refrigerant is passed through the cooling channel upstream of the forced cooling type superconducting coil 21 to the superconducting coil 21.
At the same time, the forced cooling type superconducting coil 21
The point is that the forced cooling type superconducting coil 21 is pre-cooled by drawing in from the cooling flow path on the more downstream side.

<Example> Hereinafter, the present invention will be explained according to the illustrated example.
In the figures and FIG. 2, 11 is a vacuum container, and 12 is a vacuum chamber. Reference numeral 13 denotes a heat insulating tank provided around the outer periphery of the vacuum tank 12, and is made of foam material, perlite, or the like. 14 is a vacuum pump. 15 is a liquid helium boiler in which liquid helium 16 is stored.

18a, 18b, 18c are cooling channels, cooling channel 1
Supercritical pressure cryogenic refrigerant helium gas cooled by a refrigerator (not shown) is pumped from the 8a side. A heat exchanger 19 is interposed between the cooling channels 18a and 18b, and is connected to the cooling channel 1.
The refrigerant helium gas pumped from 8a is further cooled in the liquid helium boiler 15.

21 is a forced cooling type superconducting coil (caple-in-conduit type), and as shown in FIG.
4 are stacked in a coil shape as shown in FIG. As shown in FIG. 3, a cooling channel 25 is formed between the conduit material 22 of the superconducting wire 24 and the superconducting wire 23.

One end of this superconducting coil 21 is communicated with the cooling channel 18b, and the other end is communicated with the cooling channel 18c, and refrigerant helium gas passes through the cooling channel 25 of the superconducting coil 21 and from the cooling channel 18c to the liquid helium boiler. 15, and at this time, the superconducting coil 21 is forcibly cooled by the refrigerant helium gas.

27 is an expansion valve provided in the cooling channel 18c. Reference numeral 28 denotes a delivery channel for delivering the helium gas in the liquid helium boiler I5 to the refrigerator (not shown).

Reference numeral 29 denotes a helium jetting valve, which is provided in the middle of the cooling channel 18b on the upstream side of the superconducting coil 21 via a branch channel 30. 31 is helium inhalation pulp,
It is provided in the middle of the cooling channel 18c downstream of the superconducting coil 21 via a branch channel 32.

In the above configuration, when cooling the superconducting coil 21, first, when the temperature of the superconducting coil 21 is high (approximately 100 K or more), the helium injection valve 29 is cooled.
and the helium suction pulp 31 is opened, and the refrigerant helium gas from the refrigerator is sent under pressure through the cooling channel 18a, the heat exchanger 19, and the cooling channel 18b, and the helium injection valve 2 is opened.
9 into the vacuum chamber 12, and the superconducting coil 21 is precooled from the outside by the ejected refrigerant helium gas. The pressure of the vacuum chamber 12 is approximately 1 atm, and the refrigerant helium gas ejected into the vacuum chamber 12 is absorbed into the helium suction pulp 31.
The air is sucked in from the air and returned to the refrigerator through the cooling channel 18c and the delivery channel 28. At this time, since the vacuum container 11 is also cooled by the refrigerant helium gas, the insulation tank 13 provides insulation from the room temperature.

When the superconducting coil 21 is cooled down to about 100% by pre-cooling, the jet valve 29 and the suction valve 31 are both closed as shown in FIG. 18a, heat exchanger 19,
It flows into the superconducting coil 21 via the cooling channel 18b and the cooling channel 18c. At this time, since the superconducting coil 21 has already been cooled down to about too K or less by pre-cooling, the refrigerant helium gas flows smoothly within the superconducting coil 21. Note that the helium gas remaining in the vacuum chamber 12 is exhausted by the vacuum pump 14.

FIG. 5 shows another embodiment, in which a three-way helium injection valve 34 is provided in the middle of the cooling channel 18a on the upstream side of the superconducting coil 21.
A three-way helium suction valve 35 is provided in the middle of the cooling flow path 18c on the downstream side. When cooling the superconducting coil 21, first, the helium gas is ejected from the helium injection valve 34 into the vacuum chamber 12, and the ejected refrigerant helium gas is sucked in by the helium suction valve 35, thereby cooling the superconducting coil 21 with the refrigerant helium gas. Pre-cool from outside. Thereafter, refrigerant helium gas is flowed into the superconducting coil 21 through the cooling channel 18a, the heat exchanger 19, the cooling channel 18b, and the cooling channel 18c to cool the superconducting coil 21.

FIG. 6 shows another embodiment, in which the insulation tank 13 is omitted,
A vacuum container 37 is provided in the vacuum chamber 12 so as to surround the superconducting coil 21, and a branch channel 38 that communicates with the vacuum container 37 is provided in the middle of the cooling channel 18b on the upstream side of the superconducting coil 21. A helium jetting valve 39 is provided in the middle of the branch channel 38, and a branch channel 40 communicating with the inside of the vacuum vessel 37 is provided in the middle of the cooling channel 18c on the downstream side of the superconducting coil 21. A helium suction valve 41 is provided in the middle of 40. and,
When cooling the superconducting coil 21, first open the helium injection valve 39 and the helium suction valve 41, and eject helium gas from the helium injection valve 39 into the vacuum container 37, and at the same time, transfer the ejected refrigerant helium gas to the helium suction valve 41. By inhaling the refrigerant helium gas, the superconducting coil 21 is precooled from the outside. Thereafter, the valves 39.41 are closed and the cooling channels 18a
, flowing refrigerant helium gas into the superconducting coil 21 via the heat exchanger 19, the cooling channel 18b and the cooling channel 18c,
The superconducting coil 21 is cooled.

<Effects of the Invention> According to the present invention, refrigerant is jetted from the cooling channel upstream of the forced cooling type superconducting coil 21 to the superconducting coil 21, and the jetted refrigerant is transferred to the forced cooling type superconducting coil 2.
Since the forced cooling type superconducting coil 21 is pre-cooled by suction from the cooling channel downstream from 1, when the temperature of the superconducting coil 21 is high, refrigerant helium gas flows outside the superconducting coil 21. , superconducting coil 2
The flow rate of refrigerant to the superconducting coil 21 increases, and therefore the superconducting coil 21
cooling rate becomes faster. Moreover, since no copper plate fan is attached, excess eddy current heat generation can be prevented, and the stability of the superconducting coil will not be reduced, which is a significant effect.

[Brief explanation of drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is a side sectional view of the cooling device showing the state during precooling, and FIG. 2 is a side sectional view of the cooling device showing the steady state. , FIG. 3 is a sectional view of a superconducting wire, and FIG. 4 is a sectional view of a forced cooling type superconducting coil. FIG. 5 is a sectional view of a cooling device showing another embodiment, and FIG. 6 is a sectional view of a cooling device showing another embodiment. 7th
The figure is a sectional view of a conventional cooling device. 12... Vacuum chamber, 18a, 18b, 18c...
Cooling channel, 21... forced cooling type superconducting coil.

Claims (1)

[Claims] (1) A refrigerant is passed through the forced cooling type superconducting coil (21) through the cooling channel in the vacuum chamber (12) to cool the coil (21).
In a device configured to forcibly cool the superconducting coil (21), a refrigerant is ejected from the cooling channel upstream of the forced cooling superconducting coil (21) to the superconducting coil (21), and the ejected refrigerant is transferred to the forced cooling superconducting coil (21). ) A cooling method for a forced cooling type superconducting coil, characterized in that the forced cooling type superconducting coil (21) is precooled by suction from a cooling channel on the downstream side.