JPS6128285B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a superconducting liquid level gauge used, for example, in a liquid helium level gauge.

Fig. 1 shows a conventional superconducting liquid level gauge of this kind, in which 1 is a liquid level sensor whose lower half is immersed in, for example, liquid helium 3 stored in a cryostat 2, and 1a is this liquid level sensor. 1 upper end connection part,
1d is the lower end connection part of the liquid level sensor 1, 4 is the upper end connection part 1a of the liquid level sensor 1, and the lower end connection part 1.
An indicator 5 is connected to the indicator d, and a constant current power source 5 is connected in parallel to the indicator 4.

The liquid level sensor 1 is for measuring the liquid level of, for example, liquid helium 3 stored in the cryostat 2, and is slightly higher than the boiling point (4.2K) of liquid helium. It is made of a metal that transforms into a superconducting state at high temperatures. In other words, the part of the liquid level sensor 1 that is immersed in liquid helium 3 is in a superconducting state and has zero electrical resistance, and the lower gas layer part that is not immersed in liquid helium 3 is in a normal conducting state. It takes advantage of the fact that there is electrical resistance, and now,
The level of the liquid helium 3 can be measured by passing a constant current from a constant current power source 5 through the liquid level sensor 1 and reading the voltage generated at both ends with an indicator 4. In addition, in the normally used superconducting liquid level gauge, the current value flowing through the liquid level sensor 1 is about 200 mA, and the voltage generated in the normal conductive state is about 1.5 V per 10 cm of the liquid level sensor length.
Therefore, the Joule calorific value is approximately 0.3 W per 10 cm of the length of the liquid level sensor.

Recently, large superconducting magnets for use in nuclear fusion devices or energy storage devices are being planned, but cryostats for these large superconducting magnets are several meters in height. In order to avoid sudden changes in temperature, it is necessary to gradually accumulate liquid helium. Therefore, the liquid helium level sensor is provided with a length extending from the bottom to the top of the cryostat so that it can operate at low liquid levels. In this type of operation, the amount of heat generated from the normally conducting part of the liquid level sensor is approximately 0.3W per 10cm of its length, as described above.
Therefore, for example, the length of the gas layer part is 2m
If it is, the amount of heat generated will be as much as 6W, and this value will be added to the amount of heat entering the cryostat.
This results in a loss of liquid helium. In other words, when a superconducting liquid level gauge is manufactured using the conventional method described above (FIG. 1), it has the disadvantage that it generates a large amount of heat and is extremely uneconomical.

This invention was made with attention to this point, and generates heat by dividing a relatively long liquid level sensor into a plurality of parts in the length direction and supplying current only to the necessary divided liquid level sensors. The purpose is to provide a superconducting liquid level gauge with a small volume.

That is, FIG. 2 shows an embodiment of the present invention, in which 1 is a liquid level sensor whose lower half is immersed in, for example, liquid helium 3 stored in a cryostat 2, and 1a is this liquid level sensor 1. The upper end connection part, 1d is the lower end connection part of the liquid level sensor 1, 1
b, 1c are a plurality of intermediate connecting portions provided at the intermediate portion of the liquid level sensor 1; one end 4 is connected to the lower end connecting portion 1d of the liquid level sensor 1, and the other end is connected to the An indicator 5 that can be selectively connected to each of the connection parts 1a, 1b, and 1c has one end connected to the lower end connection part 1d of the liquid level sensor 1, and the other end connected to the lower end connection part 1d of the liquid level sensor 1 through the changeover switch 6. This is a constant current power source that can be selectively connected to each of the connecting portions 1a, 1b, and 1c.

Since the superconducting liquid level gauge of this invention is constructed as described above, it is possible to use, for example, liquid helium 3
When the liquid level is between the intermediate connection part 1c and the lower end connection part 1d of the liquid level sensor 1, the constant current power supply 5 and the indicator 4 are switched between the intermediate connection part 1c and the lower end connection part 1d by the changeover switch 6. 1c, each connected to a constant current power supply 5
The current flows only between the intermediate connection part 1c and the lower end connection part 1d of the liquid level sensor 1, and the current from the connection part 1
Since there is no flow between the liquid level sensor 1 and the intermediate connection part 1c, there is no heat generation in the liquid level sensor 1 during this period. Also,
The liquid level of the liquid helium 1 is higher than the intermediate connection part 1b and 1.
Even if the changeover switch 6 is between
It goes without saying that the constant current power supply 5 and the indicator 4 are switched by , so that the liquid level sensor 1 in the gas layer section generates less heat.

In the embodiment described above, liquid helium was used as the liquid to be measured, but it goes without saying that other liquefied gases such as liquid hydrogen can also be used in addition to liquid helium.

As described above, according to the present invention, the liquid level sensor can be divided into a plurality of parts in the length direction, current can be supplied only to the necessary divided liquid level sensors, and the voltage of only these parts can be measured. This has the effect of providing a superconducting liquid level gauge that generates extremely little heat.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing a conventional superconducting liquid level gauge.
FIG. 2 is a circuit diagram showing an embodiment of the present invention. In the drawing, 1 is a liquid level sensor, 2 is a cryostat, 3 is liquid helium, 4 is an indicator, 5 is a constant current power source, and 6 is a changeover switch. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A liquid level sensor whose lower half is immersed in a liquid stored in a cryostat and which is divided into a plurality of pieces in the length direction by a plurality of intermediate connections; a constant current power source that supplies a constant current; an indicator that indicates the height of the liquid level based on the voltage generated by the liquid level sensor; and a constant current source that supplies the constant current only to predetermined sections divided by the liquid level sensor A superconducting liquid level gauge, comprising: a changeover switch for switching the constant current source so as to flow the current, and switching the indicator so as to measure only the voltage in the predetermined section. 2 Claim 1 characterized in that liquid helium is used as the liquid in the cryostat.
Superconducting liquid level gauge as described in section.