JPS60105284A - Cryostat - Google Patents

Abstract

PURPOSE:To prevent the direct inflow of heat into a helium tank, and to maintain unnecessary consumption of liquid helium at a minimum by transmitting heat from a port section over an evaporated gas in order to avoid the inflow of heat from the port section. CONSTITUTION:A stepped section 71 is formed to a helium tank 7, a gas reservoir section 7a accumulating an evaporated gas is shaped to the upper section of the helium tank 7, and a power lead 3, a liquid helium port 4, a measuring lead port 5 and a spare port 6 are fitted or bored to the gas reservoir section 72. Consequently, heat flowing from each port section 4-6 is received within the range of the gas reservoir section 72, heat transmitted over helium in the section is introduced instantaneously into a recovery pipe section space 32 in the power lead 3 by the flow 22 of helium, and an adverse effect on helium 2 in the helium tank 7 or a superconducting coil 1 is eliminated. Accordingly, heat flowing into the helium tank 7 is reduced so much, and the consumption of liquid helium lost by evaporation is minimized.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a cryostat, and more specifically, a superconducting coil, a helium tank containing liquid helium for immersion freezing the superconducting coil, and a helium tank outside the helium tank. The present invention relates to a cryostat comprising a radiation shield arranged to block radiant heat flowing into a helium tank, and a vacuum container forming a vacuum space outside the radiation shield.

[Prior art]

Conventionally, the device shown in FIG. 1 has been common as a device of this type. Namely, a liquid helium tank that freezes the superconducting coil l, a power lead that collects evaporated gas to cool itself, and at the same time sends a current to the coil l.3. Liquid helium tank for injecting liquid helium, side fixed lead 1. Measurement lead for drawing out f, etc., 1e-
It consisted of a preliminary vent, a helium tank 7, a radiation shield g to block radiant heat from the outside, and a vacuum tank 9 to keep the outside of the helium tank in a vacuum.

Superconducting coils are immersed in liquid helium to maintain the liquid helium temperature, generally <4.2 K, and can operate stably; however, in order to maintain temperature changes and minimize the amount of evaporation of liquid helium, they are generally immersed in a helium bath. On the outside of the housing 7, there is provided a radiation shield g for blocking radiant heat, and a vacuum container 9 that houses and holds the entire shield and at the same time forms a vacuum space for heat insulation.

Furthermore, a current lead to the superconducting coil 1 is required, and a gas heat exchange type is generally used for this, and the power lead 3 is attached to the superconducting coil 9 by penetrating the vacuum vessel 9. The excitation current of the superconducting coil l flows through the power lead 3, and in order to cool the heat generated, the evaporated gas of the liquid helium in the helium bath 7 is collected through the space 32 around the conductor 31 in the power lead. Ru.

On the other hand, an opening part 1 for injecting liquid helium is formed in a tubular shape from the vacuum container to the helium tank 7, and a liquid helium port <z is attached.

In addition, a left measurement lead port for pulling out a plurality of measurement lead wires 31 and a spare port 6 are generally installed.

However, since the conventional device was configured as described above, the port opening was located directly in the helium tank, so heat conduction from the port tube wall could not be ignored, and the amount of helium evaporation was reduced. The drawback was that it could not be avoided from growing larger.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above.In order to avoid heat inflow from the port part, this invention provides heat directly to the helium tank by giving this heat to the evaporated gas. The object of the present invention is to provide a cryostat that can keep unnecessary consumption of liquid helium to a minimum by preventing liquid helium from flowing into the cryostat.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

In the figure, a step 71 is provided in the helium tank 7 to form a gas reservoir 72 in the upper part of the helium tank 7 in which evaporated gas and helium are accumulated. Power lead 3. Liquid helium portli. The measurement lead boat 3 and the reserve port 6 are attached to or opened in the gas reservoir section 72. λl indicates the gas stored in the gas reservoir section 72, and Koni indicates the helium leakage into the gas/helium recovery section of the power lead 3. others,
The same parts as in Fig. 1 are given the same reference numerals.

The explanation of this part will be omitted.

Next, let us explain the action. Conventionally, the discharge from each port was directly transmitted to the helium tank.

With the above configuration, the gas reservoir section 72 has been replaced with the one that promoted heat generation by disturbing the flow of gas near the opening.
Moreover, the heat transferred to the helium in this part is immediately led to the recovery tube space 32 of the power lead 3 by the helium flow 1, and is transferred to the helium 2 or superconducting coil 1 in the helium tank 7. The negative impact on is eliminated.

Therefore, the amount of heat flowing into the helium tank is reduced accordingly, and the amount of liquid helium consumed by evaporation and lost is reduced. Further, by providing the gas reservoir part, the distance between the port opening and the helium liquid level becomes large, and direct thermal adverse effects on the helium liquid level are reduced.

〔Effect of the invention〕

As described above, according to the present invention, since the gas reservoir is provided in the upper part of the helium tank, it is possible to prevent heat from flowing in from the ports, and it is possible to save the amount of liquid helium that is lost through evaporation. Also, the operating time of the superconducting coil for the same amount of liquid helium storage.

It is possible to extend by this amount, and finally, if the operating time is the same, it is also possible to reduce the amount of liquid helium stored, and in this case, it is possible to reduce the volume of the entire cryostat.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional device, and FIG. 2 is a side sectional view of an embodiment of the present invention. l...superconducting coil, c...liquid helium, 3...power lead, da...liquid helium port. S...Measurement lead port, 6...Spare holder, 7...Helium tank,...Radiation shield, Ri...Vacuum chamber, ? /・
- Stepped part, 72... Gas reservoir part. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Teru So Ga Michi

Claims (1)

[Claims] A helium tank containing superconducting coils and liquid helium, a radiation shield placed around the helium tank,
In a cryostat equipped with a vacuum container that forms a vacuum space around the outer periphery of the radiation shield, a gas reservoir section that is formed in the upper part of the helium tank and forms a space for temporarily accumulating evaporated gas and helium; Located in the department,
A cryostat comprising an open power lead, a liquid helium reservoir, and a measurement lead port.