JPS58143506A - Superconductive device - Google Patents

Abstract

PURPOSE:To simplify the release of a permanent current without overheating and burning a superconductive coil and a permanent current switch. CONSTITUTION:When current is supplied to a superconductive coil 1, if a mechanical permanent current switch 21 is kept opened, no current will flow through the permanent switch circuit even if the superconductive coil 1 is subjected to the normal conductive transfer, accordingly, a thermal permanent current switch 22 is prevented from overheating. Moreover, the resistance of a discharge resistor 3 is not restricted by the value of the resistance when the thermal permanent current switch 22 is opened and this makes it possible to set a high resistance, whereas the magnetic energy of the superconductive coil 1 is mostly consumed in the discharge resistor 3. As a result, the superconductive coil 1 is never overheated. When the permanent current condition is released, it is only necessary to open the thermal permanent current switch 22. Since the switch takes partial charge of the extinction of arc, the mechanical permanent current switch 21 is not burned by the arc and the superconductive coil 1 can be demagnetized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a superconducting device, and firstly, to a superconducting aIili that uses a horizontal spear type permanent DC switch and is most suitable for a nine superconducting device.

Superconductor TH11, which uses a superconductor whose electrical resistance becomes zero when cooled to an extremely low temperature to form a coil and serves as a magnetic field generation source, is used for nuclear fusion, energy storage, magnetic levitation, and high energy applications. It is applied to a wide range of applications such as physics. The power loss of the superconducting coil itself is zero, and if you short-circuit both ends of the coil using a switch with zero or almost negligible electrical resistance, the attenuation of the current will be zero. It is possible to maintain a so-called persistent current state with almost no attenuation.

The formation of a persistent current will be explained using the circuit of FIG. In FIG. 1, 1 is a superconducting coil, 2 is a persistent current switch, 3 is a discharge resistor, and 4 is an excitation power source. One minute surrounded by the block 5 indicated by two-dot chain lines is kept at a cryogenic temperature. First, the persistent current switch 2 is set to the open state, and then a current is supplied from the ft source at a constant increasing rate, and the direct current flows through the superconducting coil 1 and the discharge resistor! Flows to s3.

When the supercharging current from the power supply reaches the value 2, if that value is held constant, the current flowing through the discharge resistor 3 will be determined by the inductance of the superconducting coil l and the resistance value of the discharge resistor 3. The superconducting coil IK shifts with a time constant. When the 1 m flowing to the discharge resistor 1113 finishes transferring to the superconducting coil 1, the persistent current switch 2 is closed. At the time of closing, no current flows into the permanent switch 2.

'When the current supplied from the power source 4 is reduced at a constant rate, the current flowing through the permanent TA switch 2 increases while the current flowing through the superconducting coil IK is kept at a constant value. In addition, current flows again into the discharge resistor a3.While the current supplied from the power supply is decreasing, the current supplied from the power supply, the current flowing through the switch 2, and the wL current flowing through the discharge resistor. The sum of is equal to the current flowing in the superconducting coil IK/IIK.

The supply from the power supply (after the current has become zero, the current flowing through the discharge resistor 3 is switched to the persistent current switch 2 with the above-mentioned time constant).
to move to. When the current in the discharge resistor 1113 becomes zero, the current flowing in the superconducting coil 1 and ttIt flowing in the persistent current switch 2 become equal, and the continuous circulation JjiIIIE
It becomes a flow.

Next, eternity will be explained with reference to the release of the flowing state.

In the permanent ItflL state described above, current is delivered from the power source 4 at a constant increasing rate. At this time, the voltage across the persistent current switch 20 is zero, and no current flows into the discharge resistor 3. When the current supplied from the power supply becomes equal to the current flowing through the superconducting coil 1, the current supplied from the power supply is kept at a constant value, and at this time no current flows to the persistent current switch 2. Next, after opening the persistent current switch 2, the current supplied from the power source is decreased at a constant rate of decrease.

After some of the current that was sold in the superconducting coil IK is transferred to the resistor 4, it decreases at a constant rate.
After the I current becomes zero, the current in the superconducting coil 1 attenuates according to the above-mentioned time constant.

Another way to release the persistent current state is to open the persistent current switch 2 while persistent current is flowing. If the impedance of the excitation power source 4 is set to an h value that is much larger than the value of the discharge resistor, after the persistent current switch 2 is opened, the current will flow according to the time constant determined by the inductance of the superconducting coil 1 and the resistance value of the discharge resistor. is attenuated. This method has the advantage that permanent current can be removed without turning on the power supply.

As the permanent TA switch 2, we use a so-called mechanical persistent current switch that mechanically opens and closes the contact, and a superconducting wire as the gate wire. It has a so-called thermal persistent current switch that generates.

The resistance value of the discharge resistor 3 is determined from the permissible value of the voltage applied to both ends of the superconducting coil 10, and the larger the resistance value, the lower the resistance value. This is because when the superconducting coil 1 transitions to normal conductivity due to some reason, the magnetic energy stored in the superconducting coil IK is consumed by the seed discharge resistor with a large discharge resistance value, and the magnetic energy consumed by the superconducting coil IK is small. This is because the superconducting coil 1 will not be overheated. When using an aged persistent current switch as the permanent 1m switch 2, the value of the discharge resistance is the thermal type persistent current switch tlI.
Be sure to select a value that is considerably smaller than the resistance value during running.
<must not. This is to reduce the energy consumed by the persistent current switch 2 and to prevent the persistent current switch 2 from burning out when the superconducting coil l transitions to normal conductivity due to some reason and runs. Most of the stored magnetic energy is consumed by the superconducting coil itself, and there is a risk that the superconducting coil 10 will be heated or burnt out.

The method of opening the persistent current switch 2 without operating the power supply when canceling the persistent current state is extremely simple to operate;
Mechanical persistent current switches cannot be used; mechanical persistent current switches do not have the ability to extinguish arcs.
This is because if the contact is opened while energized, the contact will burn out, and the contact resistance will become extremely large when the contact is closed next time. First, the persistent current switch 2 is placed in a cryogenic area and requires a great deal of cost and time to roll and replace the contacts.

The purpose of the first embodiment is to provide a superconducting device in which the persistent current can be released simply without overheating or burning out the superconducting coil or persistent current switch. Figure 2 is a circuit diagram showing an example of the present invention. be.

In addition, in FIG. 112, the same members as shown in FIG. 1 are given the same reference numerals. The permanent current switch is composed of a mechanical permanent current switch 21 and a thermal permanent II current switch 22 connected in series. Further, a series circuit of a switch 23 and a discharge resistor 31 is connected to the discharge resistor 3 and the lid side. With this configuration, nine persistent current switches have been obtained by incorporating the advantages of the thermal persistent current switch and the mechanical persistent current switch. The operation of the entire superconducting device is the same as that shown in FIG. 1, so a description thereof will be omitted.

When sending current to the superconducting coil l, a mechanical permanent (
If the fi switch 21 is opened, even if the superconducting coil 1 undergoes a normal conduction transition, the lll1 current will not flow to the persistent current switch circuit, and the thermal water-immersed current switch 22 will not overheat. Furthermore, the resistance value of the discharge resistor is3 is not limited to the value of the open resistance value of the thermal persistent current switch 22, so it is possible to set a high resistance value. Most of the magnetic energy is consumed by the discharge resistor 3, and the superconducting coil 1 does not overheat.

To release the persistent current state, use the thermal permanent current switch 2.
2, the switch shares the arc (14 arcs), so the superconducting coil 1 can be demagnetized without the mechanical permanent current switch 21 being burned out by the arc. Thermal permanent The current switch 22 will not overheat.

As is clear from the above, according to the book@mei, a persistent current switch that takes advantage of the advantages of both mechanical persistent current switches and thermal permanent*i switches can be obtained, so that persistent current can be released without overheating or burnout. can be done.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional super-cooling device, and FIG. 2 is a circuit diagram of an embodiment of the present invention. 1... Superconducting coil, 3.31... Discharge resistor, 4
... Excitation power supply, 21... Mechanical persistent current switch, 22... Thermal persistent current switch.

Claims (1)

[Claims] 1. A superconducting coil that is kept at an extremely low temperature and a discharge resistor are connected to a DC power source in a parallel manner, and both ends of the superconducting coil are short-circuited at a predetermined time using a persistent current switch whose electrical resistance is negligible. In the superconducting wire a that generates a persistent current state, the persistent current switch is a mechanical permanent LT current switch having transverse contacts and the superconducting wire is used as a gate wire, and is connected to the heating collar of a heating heater. A superconducting device characterized in that it is configured by connecting in series a thermal persistent current switch that exhibits a switching function according to the switching function.