JPS6160030A - Signal repeater for use in cryostat - Google Patents

Abstract

PURPOSE:To prevent thermally adverse effects on a device in a cryostat by using only a light guide and an optical fiber transmission line to a connecting part between the inside and outside of the cryostat when a repeater is set in the cryostat. CONSTITUTION:An output signal of sensors 4-6 in the cryostat 1 is led exter nally via the repeater 11. In this case, a control terminal 22 of an electrooptic signal converter 14 is connected to signal leads 23-25 provided airtightly through a wall of a thermal insulation package 12 and an output terminal of a stabilizing circuit 27 of a photoelectric motive force device 15 is connected to a power lead 28 provided airtightly through the wall of the thermal insulation package 12. Further, one end of the light guide 29 made of an optical fiber and one end of an optical fiber transmission line 30 are inserted through the wall of the package 12 airtightly. Thus, the elements connecting the inside and outside of the cryostat 1 are the light guide 29 and the optical fiber trans mission line 30 with bad heat conduction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a signal relay device for use in a cryostat, which is used when transmitting a signal from the inside of the cryostat to a normal temperature atmosphere field.

[Technical background of the invention and its problems]

Recent advances in cryogenic technology have been remarkable and are being applied to various fields. The main part of a device that applies such cryogenic technology, for example a superconducting magnet, is usually constructed by accommodating a superconducting coil in a cryostat and containing liquid helium to cool the superconducting coil to a cryogenic temperature. ing.

By the way, in a cryostat that contains cryogenic liquid and equipment that is cooled to a cryogenic temperature by this liquid, the status of the equipment can be checked using various electrical methods during testing or operation. Frequently, measurements must be made using sensors of the type transducer, which convert the measured quantity into the form of a current or voltage level. In such cases, conventionally,
One end of at least two lead wires is connected to a sensor set inside the cryostat, and the other end of these lead wires is passed through the wall of the cryostat in an airtight manner to the outside.
In other words, a method is adopted in which it is extended to a room-temperature atmosphere field.

However, in this type of system, for example, as the number of sensors increases, the number of lead wires also increases, and these lead wires are generally made of a material with good thermal conductivity. A large number of heating devices enter the cryostat through the cryostat, which not only has an adverse thermal effect on the equipment housed inside the cryostat, but also requires the use of large-capacity refrigeration hoes, etc. was there.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to suppress the amount of heat entering the cryostat to a sufficiently small value, and to direct multiple sources from inside the cryostat toward the room temperature atmosphere field. It is an object of the present invention to provide a signal relay device for use in a cryostat that can transmit signals well and is highly effective when, for example, a plurality of transducer type sensors are set inside the cryostat.

[Summary of the invention]

A relay device according to the present invention includes: a heat insulating container disposed in a cryostat containing a cryogenic liquid; and at least one system of electrical-to-optical signal converting device housed in the heat insulating container and converting an electrical signal into an optical signal. a photovoltaic device housed in the heat insulating container and serving as a power source for the electrical-to-optical signal conversion device; a light guide that guides light towards the heat-insulating container; an optical fiber transmission line that has one end that airtightly penetrates the wall of the heat-insulating container and guides the optical signal sent from the electrical-to-optical signal converter to the outside; It is comprised of a power supply lead wire that is provided to airtightly penetrate a wall and extend the output terminal of the photovoltaic device to the outside, and a signal lead wire that leads an electrical signal from the outside to the electrical-optical signal converter. ing.

〔Effect of the invention〕

With the above configuration, when this relay device is actually set in a cryostat, the only parts that connect the inside of the cryostat and the room temperature atmosphere are the light guide and the optical fiber transmission line. These light guides and optical fiber transmission lines are thermally insulating materials. Therefore, a signal can be transmitted from inside the cryostat to the normal temperature atmosphere without allowing heat to enter the cryostat. Therefore, there is no risk of adverse thermal effects on equipment etc. housed in the cryostat, and there is no need for a freezing rock or the like with a particularly large capacity.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

The figure shows an example in which a relay device according to an embodiment of the present invention is actually incorporated into a cryostat and transmits signals.

In the figure, 1 indicates a cryostat formed with an inner and outer tank structure, 2 indicates a device housed in the inner tank of the cryostat 1, and 3 indicates a device housed in the inner tank of the cryostat 1. A cryogenic liquid, for example liquid helium, is shown which cools the device 2 to a cryogenic temperature.

In the cryostat 1, a sensor 4.5 in the form of a transducer is placed in close contact with the surface of the device 2 and detects the surface distortion of the device 2 in the form of an electrical signal level.
Also provided is a transducer-type sensor 6 that detects the temperature around the device 2 in the form of an electrical signal level.

The output signals of these sensors 4, 5, and 6 are led to the outside of the cryostat 1 via a signal relay device 11.

The relay device 11 is configured as follows.

That is, the heat insulating container 12 is arranged so as to be immersed in the liquid helium 3. This heat insulating container 12 has a U heat layer 13 formed in the outermost part, and this super heat insulating layer 13
The presence of this prevents the inside from being cooled below, for example, 0°C.

Inside the heat insulating container 12, an electric-to-optical signal converter 14, a photovoltaic device 15, and a powder 16 having a large heat capacity, such as alumina, are housed.

In this example, the electrical-to-optical signal converter 8 and 14 are comprised of three systems: a first, second, and third system 17, 18, and 19. Each system is substantially equally configured, and each system is comprised of a semiconductor laser 20 and a drive circuit 21 that drives this laser 20. The drive circuit 21 is configured to control the drive current of the semiconductor laser 20 in accordance with the level of a signal applied to its control terminal 22. And each of the above drive circuits 2
The control terminals 22 of 1 are connected to signal lead wires 23, 24, and 25, which are respectively provided by penetrating the wall of the heat insulating container 12 in an airtight manner.
It is connected to the. Note that the portions of the lead wires 23, 24, and 25 that penetrate the super-insulating layer 13 are several hundreds of wires each.
The wire diameter is on the order of [cμm].

The photovoltaic device 15 includes a photovoltaic element 26 composed of a solar cell or the like, and a stabilizing circuit 27 that includes a capacitor that stores the output of this element and a stabilizing element that stabilizes the voltage across the capacitor. It is made up of.

The output terminal of the stabilizing circuit 27 is connected to each drive circuit 21.
It is connected to the power supply lead wire 28 which is provided to pass through the wall of the heat insulating container 12 in an airtight manner. The power supply lead wire 28 is connected to the power supply terminal of each of the sensors 4.5.6, and the output ends of these sensors 4.5.6 are connected to the aforementioned signal leads 23, 24, 25.

Therefore, inside the insulating container 12, this insulating container 12
One end of a light guide 29 formed of an optical fiber and one end of an optical fiber transmission line 30 are inserted through the wall of the optical fiber in an airtight manner.

One end of the two light guides located inside the heat insulating container 12 is arranged to face the light receiving surface of the photovoltaic element 26, and the other end passes through the upper wall of the cryostat 1 in an airtight manner. It is coupled to a light source device 31 provided outside the cryostat 1. On the other hand, the optical fiber transmission line 30 is actually composed of three bundled optical fibers. The end of each optical fiber located inside the heat insulating container 12 is coupled to the optical output sending end of the corresponding semiconductor laser 20 of the electrical-to-optical signal converter 14, and the end of each optical fiber located outside the heat insulating container 12 The portions hermetically penetrate the earthen wall of the cryostat 1 and are coupled to the light receiving elements 32a, 32b, and 32C. The outputs of the light receiving elements 32a, 32b, and 32c are introduced into a recording device 33 and a display device 34.

Note that 35 in the figure indicates liquid nitrogen for pre-cooling stored between the inner tank and the outside (■).

With such a configuration, when the light source device 31 is operated now, the light emitted from the light source device 31 will be directed to the light guide 29.
The light is received by the photovoltaic device 15 via. therefore,
A DC voltage of a predetermined level appears at the output ends of the photovoltaic devices 1 and 5. This voltage puts each sensor 4.5.6 into operation and also puts each drive circuit 21 into operation. Each drive circuit 21 applies a drive current to the corresponding semiconductor laser 20 according to the output signal level of the corresponding sensor.
supply to. Therefore, each semiconductor laser 20 emits a light output with an intensity corresponding to the output of the corresponding sensor. The optical output of each semiconductor laser 20 is introduced into light receiving elements 32a, 32b, and 32c via each optical fiber constituting an optical fiber transmission line 30, and is converted into an electrical signal by these elements, and this signal is transmitted to a recording device. 33 and display device 34. Therefore, the recording device 33 records the ever-changing amount of surface distortion of the open lid 2 and the 8 degrees around it, thereby achieving the objective.

In this case, the light guide 29, which has poor heat conduction, is used as an element to communicate between the inside and outside of the cryostat 1.
The target rA amount is measured using only the optical fiber transmission line 30 and the optical fiber transmission line 30. Therefore, it is possible to carry out measurements while suppressing the amount of heat entering into the cryostat 1 to a sufficiently small value, and as a result, the effects of the present invention described above are exhibited.

Note that the present invention is not limited to the embodiments described above. That is, by connecting a temperature control circuit and a heater in series between the output terminals of the photovoltaic device 15 and appropriately energizing the heater with the circuit, the inside of the heat insulating container 12 is prevented from becoming too cold below the allowable temperature of the semiconductor laser. It may also be possible to prevent this. Further, in the embodiment, three signals are relayed, but it is of course possible to relay more signals. Further, other semiconductor light emitting devices may be used in place of the semiconductor laser.

[Brief explanation of drawings]

The figure is a schematic configuration diagram of an example incorporating a signal relay device according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Cryostat, 2... Equipment, 3... Liquid helium, 4.5.6... Sensor, 11... Signal relay device, 12... Heat insulation container, 14... Electricity- Optical signal converter, 15... Photovoltaic device, 23.24.2
5...Signal lead wire, 28...Power lead wire,
29... Light guide, 30... Optical fiber transmission line.

Claims (2)

[Claims] (1) A device that is placed in a cryostat containing a cryogenic liquid and relays signals, and includes an insulating container and at least one electrical system housed in the insulating container that converts electrical signals into optical signals. - an optical signal converter; a photovoltaic device housed in the heat insulating container and serving as a power source for the electrical-to-optical signal converter; a light guide that guides light toward the electromotive force device; an optical fiber transmission line that has one end that airtightly penetrates the wall of the heat insulating container and guides the optical signal sent out from the electrical-to-optical signal converter to the outside;
A power supply lead wire that airtightly penetrates the wall of the heat insulating container and extends the output terminal of the photovoltaic device to the outside, and a signal lead wire that guides an electric signal from the outside to the electric-optical signal converter. A signal relay device for use in a cryostat, comprising: (2) A signal relay device for use in a cryostat according to claim 1, wherein a substance having a large heat capacity is housed in the heat insulating container together with each of the elements.