JPS62276806A - Apparatus and method for controlling superconducting device - Google Patents

Abstract

PURPOSE:To improve diagnostic efficiency by providing a current reference changing by a comparatively slow sweeping gradient altering superconducting coil currents and a current reference, which does not vary superconducting coil currents and which changes by a fast sweeping gradient altering other supply currents and the currents of a superconducting wire. CONSTITUTION:When coil currents caused to flow through a superconducting coil 1 are made to rise, the superconducting coil 1 is kept previously under a superconductive state while a heater 5 is conducted and a superconducting wire 4 is brought to a normal conductive state, and output currents from a power supply 2 for the superconducting coil are controlled so as to augment coil currents up to a final command at a current increase rate where a quenching accident is not generated in the superconducting coil 1. The heater 5 is turned OFF for a period when the superconducting wire 4 can maintain the normal conductive state by its own Joule heat generation, the heater 5 is turned ON again before and after coil currents reach the final command, and the output currents from the power supply for the superconducting coil and the coil currents are equalized. Supply currents are minimized up to a zero value at a current reduction rate where a quenching accident is not generated in the superconducting line, and the operation of the power supply for the superconducting coil is stopped.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Object of the Invention) (Industrial Application Field) The present invention provides a medical diagnostic device (NHR-
The present invention relates to superconducting devices for creating superconducting persistent current loops, such as CT) and power storage magnets that convert and store electric power into magnetic energy.

(Prior Art) FIG. 6 is a block diagram of a conventional superconducting device that creates a persistent current loop. The conventional superconductor 4 device is a superconducting coil power source (hereinafter referred to as a DC power source) for exciting the superconducting coil 1.
2, a persistent current switch 3 connected in parallel with this superconducting coil 1 to create a persistent current loop together with this superconducting coil 1, and a superconducting wire 4 in this persistent current switch 3.
a heater 5 for heating the heater 5, a heater power supply 6 for energizing the heater 5, and a superconducting coil 1 and a DC power supply 2 in the event of an abnormality.
The superconducting coil 1 is constructed of a DC breaker 7 for interrupting the current, and a protective resistor 8 for consuming the magnetic energy stored in the superconducting coil 1 to protect the superconducting coil 1 when the DC breaker 7 is interrupted. ing. The superconducting coil 1
and persistent current switch 3 to achieve superconducting state,
It is stored in a cryogenic container (thaliostat) 9.

The shunt resistor 10 is used as a current detector during constant current control of the DC power supply 2, and the detected power supply current 11 is added to the adder/subtractor 12 via the amplifier 11.

The persistent current switch 3 is composed of a superconducting wire 4 and a heater 5, and when the heater 5 is not energized from the heater power source 6, liquid helium (not shown) in the cryogenic container 9 is released.
), the temperature becomes below the critical temperature Tc, and the superconducting wire 4 enters a superconducting state. When the heater 5 is energized from the heater power supply 6, the superconducting wire 4 is heated to a temperature equal to or higher than the critical temperature TC, becomes a normal conductive state, and has an electrically constant finite resistance value R.

With the above configuration, the operation for creating a persistent current loop is as shown in the time chart of FIG. 7.

First, it is assumed that the superconducting coil 1 and persistent current switch 3 in the cryogenic container 9 are already in a superconducting state, and the DC power supply 2 is not outputting voltage or current. When a current is applied to the superconducting coil 1 from this state, first, at time T1, the heater power source 6 is turned ON, and the heater 5 heats the superconducting wire 4 of the persistent current switch 3 to bring it into a normal conducting state, thereby resisting the superconducting wire 4. Give it the value R.

Next, at time T2, the DC power supply 2 is activated to generate voltage and current output, and the superconducting coil 1 is energized.

At this time, if a large current is suddenly passed through the superconducting coil 1, quenching will occur and the superconducting state will not be maintained.
The DC power supply 2 is controlled so that the current I3 flowing through the superconducting coil 1 is gradually increased at a limited rate of change.

Therefore, a reference value I ref is given to the adder/subtractor 12 so that the power supply current 11 of the DC power supply 2 changes from O to Io at a predetermined rate of change. That is, the DC power supply 2 is driven according to the deviation ε between this reference value I rcf and the current detection value (feedback value) obtained from the shunt resistor 10 via the amplifier 11, and the superconducting current is passed through the superconducting current loop in the cryogenic container 9. The power supply current 11 is controlled by IL. As a result, the power supply current 1
1 gradually increases from O to Io at a constant rate of change according to the reference value Ire.During this time, the DC power supply 2 maintains a very small constant voltage ■
A small constant current I2 flows through the superconducting wire 4 in accordance with this voltage V. Therefore, the superconducting coil 1 is supplied with a current 13, which is obtained by subtracting the minute constant current 2 from the power supply current 11.
(I3=11-12> flows as shown in FIG. 7).

The power supply current 11 continues to increase and eventually reaches the final target current value Io.
When the deviation ε becomes zero, the voltage generated by the DC power supply 2 becomes approximately O. As a result, the current ■2 that had been flowing through the superconducting wire 4 until then is reduced to the resistance valve R of the superconducting wire 4.
and the time constant determined by the inductance of superconducting coil 1 (
τ = L/R) and becomes O (I 2 = O)
. Therefore, at this point, the current flowing through the superconducting coil 1 is
3 and the power supply current 11 are equal, and the current value becomes 1o (
11=13=Io).

Next, in this state, when the heater power source 6 is turned off at time T3, the superconducting wire 4 is cooled by liquid helium,
It becomes a superconductor and its resistance value becomes zero.

After time T4 when the resistance value of the superconducting wire 4 becomes zero,
The power supply current 11 flowing through the DC N source 2 is gradually reduced, and the reduced power supply current 1 is transferred to the superconducting wire 4 in the opposite direction.
Run as 2. That is, after time T4, the coil current I3 does not change, and this current ■3 is divided into the power supply current 11 and the current I2 of the superconducting wire 4, and the current I2 that gradually decreases the current ■1 is shown in the figure. Gradually increases in the opposite direction of the arrow. Note that if the current 11 is suddenly decreased at this time, the current I2 flowing through the superconducting wire 4 will suddenly increase, and there is a risk that the superconducting wire 4 will return to the normal conductive state. Based on No. 11, the current is controlled to gradually fall according to the Q value I ref.

As a result, the power supply current ■1 becomes completely O at time T5,
A circulating superconducting persistent current loop of persistent current 13=12=IO is obtained by being disconnected from the DC power supply 2.

(Problems to be solved by the invention) Medical diagnostic device (N)I applying this conventional superconducting device
The target atomic nucleus to be imaged in R-CT is only one type of proton (hydrogen nucleus), and it has generally been a type that is fixedly installed at a hospital for diagnosis. For this reason,
In the conventional N1 (I?-CT), the intensity of the magnetic field generated by the superconducting coil 1 described above can be kept constant, and a method is adopted in which this superconducting persistent current loop is maintained for a long period of time, and many patients are diagnosed during this period. Ta.

That is, there was little need to frequently change the strength of the magnetic field generated by the superconducting device.

However, in recent diagnostic medicine, nuclei other than protons (hydrogen nuclei), such as fluorine (F) and sodium (
There is a demand for more precise diagnosis by imaging atomic nuclei such as Na> and phosphorus (P). To achieve this requirement, it is necessary to create a magnetic field of optimal strength matching the nuclear magnetic resonance frequency of the target atomic nucleus. Of course, the value of this generated magnetic field varies depending on the target atomic nucleus to be imaged, and in order to obtain images of different atomic nuclei, it is necessary to change the intensity of the generated magnetic field of the superconducting device.

Generally speaking, in recent diagnostic medicine, an MRI diagnostic vehicle (nuclear magnetic resonance medical diagnostic vehicle) is being considered, which carries a set of medical diagnostic equipment including the above-mentioned superconducting device on a large trailer and travels around to diagnose various locations.

In this case, it is necessary to first reduce the strength of the magnetic field generated by the superconducting device operating in a persistent current loop to zero or extremely weak before moving. This means that the magnetic field generated during diagnosis generally ranges from 0.3 Te5la to 2.0 Te5la (1 tes
This is because the magnetic field is as strong as la=10,000 Gauss, so it is impossible to move it by trailer as it is.

In this way, in the case of MRI diagnostic vehicles as well, there is a need to frequently change the strength of the magnetic field generated by the superconducting device.

However, in the conventional superconducting device control method described above,
As shown in Fig. 7, the superconducting coil 1 is
Once the persistent current loop is obtained, the power supply current 11 is decreased (since the drawn gradient is the same, the specified persistent current loop can be obtained. There was a problem in that it took a very long time until the power supply 2 stopped.

To explain this in terms of the medical diagnostic equipment (NMR-CT) mentioned above, the series of control times can reach several hours, and during this time it is a waste time during which the patient cannot be diagnosed and the original diagnostic function cannot be performed. becomes.

This is a serious defect from the standpoint of diagnostic efficiency, and improvements have been sought.

As roughly shown in FIG. 7, while the current I3 of the superconducting coil 1 is being started up using the DC power supply 2,
Since the heater 5 is kept in the ON state, the inside of the cryogenic container 9 is heated unnecessarily, and the expensive liquid helium used as a coolant is unnecessarily evaporated, resulting in economic damage to the equipment. There was also a problem in that it had an adverse effect on the lifespan.

The first object of the present invention has been made based on the above circumstances, and it is possible to solve the problem without increasing the rating of the superconducting power source or changing the structure of the superconducting coil to improve the current rate of change, which would increase the cost. Obtaining a given persistent current loop,
It is an object of the present invention to provide a control method for a superconducting device that minimizes a series of control times until stopping the power supply and improves diagnostic efficiency.

A second object of the present invention is to provide an economical and highly reliable superconducting device that can suppress evaporation of expensive liquid helium and extend the life of the device.

A third object of the present invention is to provide a superconducting device that can obtain images of different atomic nuclei by changing the intensity of the magnetic field generated by the superconducting device.

[Structure of the invention]

(Means for solving the problem) In order to achieve the above purpose, a permanent current switch (consisting of a superconducting coil and a persistent current switch (superconducting wire and a heater for bringing it into a normal conduction state) connected in parallel with the coil is used. )
is housed in a cryogenic container, and a DC power source whose output can be arbitrarily changed is connected to the superconducting coil and persistent current switch, and a closed loop formed by the superconducting coil and superconducting wire has a predetermined size. In a superconducting device that creates a persistent current loop by circulating a current of a reference generator having a current reference value having a second sweep gradient that changes the current flowing through the DC power source and the superconducting wire without changing the current after the coil current reaches the target value; A timing control means is provided for switching the current reference value and the energization timing of the heater at a predetermined timing, and the absolute value of the first sweep gradient is
This is characterized by increasing the absolute value of the second sweep gradient.

(Function) When starting up the coil current flowing through the superconducting coil, the present invention
After maintaining the superconducting coil in a superconducting state in advance and turning the superconducting wire into a normal conducting state by energizing the heater,
The output current of the superconducting coil power supply is controlled so that the coil current increases to the final target value at a current increase rate that does not cause a quench accident in the superconducting coil, and in the process of increasing the coil current, the superconducting wire The heater is turned off for a period during which the normal conductivity state can be maintained due to Joule heat generation of R: resistance of the superconducting wire), and after the output current of the superconducting coil power source and the coil current become equal, the current reduction rate is such that a quenching accident of the superconducting wire does not occur. The power supply current is reduced to zero and the operation of the power supply for the superconducting coil is stopped.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure shows a method of controlling a superconducting device according to an embodiment of the present invention. In the figure, the same reference numerals as in FIG. 6 indicate the same or corresponding parts, and the differences from FIG.
6. A timing control section 17, an operation command switch 18, and an operation mode changeover switch 19 are added.

The above setting device 13A is used to set the j1 draft angle A used when changing the superconducting coil current.
Reference numeral 33 is for setting a sweep gradient B used when changing only the voltage, the current, and the current of the superconducting wire without changing the coil current. Further, the setting device 15 is a setting device for setting the target current Io similarly to the conventional device. Reference generator 1
6 is the target current Io set by the target current setter 15 and the sweep gradient A set by the sweep gradient setter 13A or 1313.
or B, and set the setting device 13A or 1 until the current 11 flowing to the power supply reaches the target current 1o or zero.
It is a device that outputs a current reference IA or IB that changes according to the sweep gradient A or B set in step 33. The timing control unit 17 is a device that reads the power supply current (1) and the target current Io, compares them with each other, and detects ON-OFF timing of the heater power supply and switching timing of the current reference IA or IB.

FIGS. 2(8), 2(B) and 2(C) are detailed control flowcharts of the reference generator, and FIG. 2(D) is a detailed control flowchart of the reference generator.

(E) and (F) show detailed il control flowcharts of the timing control unit V, respectively.

Based on FIG. 1, FIG. 2 (8) to ([), and FIG. 3 explained above, the operation when creating a persistent current loop of a predetermined current magnitude in the superconducting coil 1 from a non-excited state will be explained. do. In this case, by turning on the side switch 18 that starts the operation mode changeover switch 19 from the non-excited state, the timing 1llll control section H is set as shown in Fig. 2 (D).
, (E) After performing the predetermined processing indicated by # and ([) (setting Io (I4) on the setting device 15, capturing the target current Io (14), storing it, and determining whether or not it is non-excited), the heater Turn on the power supply 6 (time 11). As a result, the superconducting wire 4 is heated.

Next, the timing control unit 17 sets the current reference to the reference generator 16 at a scheduled time T12 after a predetermined time t11 required for the superconducting gland 4 to change from the superconducting state to the normal conducting state after turning on the heater power source 6. Issue an IA output command. On the other hand, the reference generator 16 is also
) cl”; and the predetermined processing shown in (C) (setting device 1
Setting of gradient A by 3A, importing and storing gradient A,
Setting of slope B by setter 13B, loading and storing slope B, setting of target current Io (I4) by setting unit 15, loading and storing of IO (I4), count value N=
0. a=A (4rm drag slope), b=o settings). This IA is a reference value for gradually changing the power supply current 11 to the target current Io set by the target current setting device 15 according to the sweep gradient A, that is, the rate of change of current, which is preset by the setting device 13A. What is important here is that since the superconducting coil (3) also changes according to this target current IA, this rate of change is
The point is that the rate of change is set below the rate of change determined by the @ structure of the coil. Therefore, while the coil current I3 is changing according to this rate of change, the coil 1 is not quenched.

The DC power supply 2 is controlled to raise the power supply current 11 at a constant rate of change based on the deviation signal ε from the adder/subtractor 12.

As a result, a minute constant voltage V is generated from the DC power supply 2,
The current (3) is passed through the superconducting coil and the current (2) is passed through the superconducting wire 4 as described above. However, in the case of this embodiment, in order to prevent unnecessary evaporation of liquid helium, the superconducting wire
When it becomes normal conductivity, the heater power source 6 is turned to 0FFt, and thereafter normal conductivity is maintained by self-heating.

Therefore, at time T13 after the waiting time t12 from time T12 until the superconducting wire 4 can maintain the normal conductivity state, the timing controller 17 outputs a stop command and turns off the heater power supply 6.

On the other hand, the timing control unit 17 that has read the target current value Io from the setting device 15 calculates in advance a current value 1o - α = I6 that is smaller than this Jo by a predetermined value α, and detects it from the shan 1 - the resistor 10. When it is detected that the power supply current 11 has reached this current value I6, a start command is outputted to the heater power supply 6 again at time T14, and the power supply 6 is turned on.

If the power supply current 11 becomes equal to the current C and the current Io, the current 2 decreases as described above, so normal conductivity cannot be maintained only by the Joule heat (RI22) generated in the superconducting wire 4 itself. By turning on the heater power source 6 in advance, the normal conducting state of the superconducting wire 4 is maintained. In addition,
R4 is the resistance value when the superconducting wire 4 is in a normal conducting state. As a result, superconducting coil current (13) = target current (I
o) can be realized. The timing control unit 17 is at time T14.
A command to turn off the heater power source 6 is output at time T15 after the elapse of time t13 until the current I3 reaches the target current Io. Heater power supply 6 at time T15
0FFL, the superconducting wire 4 is cooled by liquid helium LHe (not shown) and enters a superconducting state.

The time required for the superconducting wire 4 to enter the superconducting state from time T15 is determined in advance by the cooling capacity of LHe and the heat capacity of the persistent current switch 3, and is the predetermined time t14. When the predetermined time t14 has elapsed since the heater power supply 6 was turned off, the timing control section 17 issues an output command of the current reference IB to the reference generator 16. This IB gradually changes from the target current Io set by the setter 15 to zero current according to the jIchikawa gradient B set in advance by the setter 13B. The DC power supply 2 controlled by the deviation of the adder/subtractor 12 is
Since the reference value II3 gradually decreases, the power supply current ■125! , and lower it. What is important here is that the sweep gradient B of 1B changes the current at a much faster gradient than the (hanging gradient A) of IA.

As mentioned above, this is because the load side viewed from the power supply 2 side, that is, the superconducting coil 1 and the superconducting wire 4, are in a superconducting state with the resistor U. Roughly speaking, in this section, the superconducting coil current 3 does not change, and the superconducting wire Only the current (2) and the power supply current (2) are changing.

On the other hand, the timing control section 17 receives this power supply current 11 as input, and detects the timing when I1 reaches the opening. This is time T17, and from now on a predetermined time t11
After 3 lapses, a command to stop the current reference IB is output to the reference generator 16, and at the same time, the DC power supply 2 is completely stopped to complete the series of controls.

Next, the operation when creating a persistent current loop state of another predetermined current (4) from a persistent current loop state of a predetermined current Io will be explained with reference to FIG. In this case, the operation mode selector switch 19 is switched to the side that starts from the excitation state. At this point, the reference generator 16 outputs the target current I that was operated last time.
o is stored, another target current I4 is set using the current setting device 15, and this I4 is input.

First, at time T21, the operation command switch 18 is turned on.
By doing so, the timing control section 17 is controlled by the reference generator 16.
An output command of current uQII3 is issued to the current uQII3.

This IB is a reference value for gradually changing the power supply current 11 up to the target current 1o set during the previous operation at 15 according to the current change rate of the sweep gradient B that must be set in advance with the setting device 13b as described above. be. What is important here is that the superconducting coil 1 and the superconducting wire 4 on the load side are in a persistent current state in which a persistent current I3 with zero resistance flows back, and the above-mentioned sweep gradient B side with a fast rate of change can be used. The power supply 2 is operated according to this current reference IB to raise the power supply current 11 to the target value 1o. At time T22, the timing control 81) detects the timing when the power supply current 11 reaches the target value Io during the previous operation, and then controls the timing control 81) for a predetermined time t22.
The heater power supply 6 is turned on at time T23.
Outputs the ZAZZER command. Here, the heater power is turned on and a predetermined time ↑23 has elapsed. When the superconducting wire 4 becomes normal conductive, the superconducting wire 4 waits for a finite resistance value R, and the power supply current ■1 becomes the superconducting coil current I3 and the persistent current switch current ■2. Divided into. The timing setter 17 issues a switching command to the reference current generator 16 to output the current reference IA after a predetermined time t23 has elapsed after turning on the heater power supply. This time is time T24 in the figure. This current reference IA is a reference value that changes at a sweep gradient A toward the target current 4 set before operation.

The superconducting coil current 3 also changes due to the power supply 2 controlled according to this IA. In addition, the timing control unit 17 outputs the superconducting wire 4 from time T24 in the figure when it outputs the signal to the current base QI.
After a time t24 sufficient for maintaining the normal conductivity state, a command to turn off the heater power source 6 is output. This is time T25.

On the other hand, the timing control unit 17 inputting the final target current I4 and the power supply current 11 calculates 14 to α-I4, which is smaller than this current 4 by a predetermined value α, so that the power supply current 11 reaches this I4. detect the signal. And T26 in the figure
In response to this signal, a command is issued to turn on the heater power supply 6 again. As a result, the superconducting coil current 13=final target current I4 can be realized as described above. and time T
By turning off the heater power source 6 at step 27, the superconducting wire 4 enters a superconducting state, and this state is at time T2B.

The timing control unit 17 then outputs a signal to the reference current generator 16 to switch to the current reference IB. This I
a changes according to the sweep gradient B until the current is zero. In this section, the superconducting coil current I3 does not change, and only the current (2) of the superconducting wire 4 and the power supply current (2) change, so that the power supply current 11 can be lowered with a fast sweep gradient B. ■At time T29 when 1 becomes zero, the timing control unit detects this and outputs a command to stop the current reference IB to the current reference generator 16 after a predetermined time t28 has elapsed, and at the same time completely shuts off the DC power supply 2. Stop and complete the series of controls.

Further, in this explanation, the target current (4) is set higher than Io, but it can also be set lower than Io, and furthermore, it can be set to zero to put the coil in a non-excited state.

In general, in the embodiment described above, the superconducting or normal conducting state of the superconducting wire 4 is detected after a predetermined period of time has elapsed since the heater power source 6 was turned on or off. By attaching a temperature sensor or the like to directly monitor the temperature of the wire 4, it is also possible to reliably detect the superconducting or normal conducting state. By doing so, it is possible to roughly shorten the period between 0Ntll1 of the heater power source 6, and it is possible to further suppress the consumption of liquid helium.

Further, although the above-described embodiment deals with the case where the superconducting coil current I3 is started up, it goes without saying that the same can be applied to the case where the superconducting coil current I3 is turned down.

A time chart of this embodiment of the current (3) fall is as shown in FIG.

(Effects of the Invention) As described above, according to the present invention, there is a current reference that changes with a relatively slow sweep gradient that changes the superconducting coil current, and a superconducting coil current that does not change and other power supply currents or superconducting wires. By providing a current reference that changes with a fast sweep gradient that changes the current of It is possible to provide a control method for a superconducting device that minimizes a series of control times until the power supply is stopped and improves diagnostic efficiency.

Furthermore, according to the present invention, the superconducting wire of the persistent current switch is turned on in a normal conductive state, and the heater power source is turned off to
By suppressing unnecessary heat generation in the cryogenic container, we can suppress the consumption of expensive liquid helium and extend the life of the equipment, creating an economical and highly reliable superconducting device. is obtained.

Also, when changing the magnetic field generated by the superconducting coil 1, the setting value of the current setting device 15 is changed from, for example, Io to 14,
By controlling the DC power supply 2 and the heater power supply 6 by operating the timing control unit 17 in the same manner as the control in the case of the target current Io, efficient liquid helium (L
It is possible to provide an economical superconducting device that consumes less He 2 ).

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram that does not show one embodiment of the present invention, and FIG. 2 (A)
, (B) and (C) are detailed control flowcharts of the reference generator 16 of the present invention; FIGS. 2(D) and (t)
3 and 4 are time charts showing the control operation of the present invention. FIG. 5 is a time chart of another embodiment. The figure is a block diagram of the conventional device, and FIG. 7 is a time chart showing the 1 til control operation of the conventional device. 1...Superconducting coil 2...DC power supply 3...
Persistent current switch 4...Superconducting wire 5...Heater
6... Heater power supply 7... DC breaker
8...Protective resistance 9...Cryogenic container 10
...Signal resistor 11...Amplifier 12
...Adder/subtractor 13A, B...Sweep gradient setter 15...Current setter 16...Reference generator 1
7...Timing control section 18.19...Switch. Agent Patent Attorney Noriyuki Chika Yudo Hirofumi Mitsumata Figure 1 Figure 2 (A) Figure 2 1. ) Figure 2 (ρ) Ttt 7'/2Tt3 T14 7/s
Ttt Tt7TtBSpecial F, 7 T2/ T2y million J Tya T2s
T2t It T, e Try 7'+? +
Unpublished period Fig. 5 Fig. 6 A1 Gi F7.7 Fig. 7

Claims (9)

[Claims] (1) A persistent current switch that is installed in a cryogenic container and forms a current loop together with a superconducting coil (this persistent current switch is connected to a superconducting wire connected in parallel to the superconducting coil and a heater placed near the superconducting wire). a superconducting coil power supply that is provided outside the cryogenic container and supplies current to the current loop, and a heater power supply that supplies current to the heater, thereby giving the current loop a predetermined size. In a superconducting device that circulates a current to create a persistent current loop, a first current reference having a first sweep gradient that changes the superconducting coil current;
a sweep gradient setting means having a second current reference having a second sweep gradient that changes the current flowing through each of the superconducting coil power supply and the superconducting wire without changing the superconducting coil current; A superconducting device characterized in that it is provided with a target current setting means for determining a target current, and a control means for switching the operation mode of the two current-based superconducting devices at a predetermined timing. (2) In the superconducting device according to claim 1, the heater power source is turned on only for a predetermined time when the DC power source is turned on or off, and for a predetermined time when the current in the superconducting coil reaches a predetermined current. A superconducting device characterized in that it is provided with a control means for controlling. (3) In claim 1, the control means is a reference generation unit that inputs the first current reference, the second current reference, and the target current setting value to generate a current reference for the superconducting coil power source. and a timing control section that inputs a signal corresponding to a power supply current, an operation command, and an operation mode switching command to switch the operation mode. (4) A persistent current switch that is installed in the cryogenic container and forms a current loop together with the superconducting coil (this persistent current switch is connected to a superconducting wire connected in parallel to the superconducting coil and a heater placed near the superconducting wire). a superconducting coil power supply that is provided outside the cryogenic container and supplies current to the current loop, and a heater power supply that supplies current to the heater, thereby giving the current loop a predetermined size. In a superconducting device that creates a persistent current loop by circulating a current, when starting up the coil current flowing through the superconducting coil, the superconducting coil is maintained in a superconducting state in advance, and the heater is energized to make the superconducting wire normally conductive. After the state is set, the output current of the superconducting coil power source is controlled so that the coil current is increased to the final target value at a current increase rate that does not cause a quench accident in the superconducting coil, and in the process of increasing the coil current. The heater is turned off for a period during which the superconducting wire can maintain a normal conducting state due to its own Joule heat generation, and the heater is turned off again before and after the coil current reaches the final target value at a predetermined time constant τ=L/R (where L: The output current I of the superconducting coil power supply is
Control of a superconducting device in which the power supply current is reduced to zero at a current reduction rate that does not cause a quench accident of the superconducting wire after _1 and the coil current become equal, and the operation of the power supply for the superconducting coil is stopped. Method. (5) A persistent current switch that is installed in the cryogenic container and forms a current loop with the superconducting coil (this persistent current switch is connected to a superconducting wire connected in parallel to the superconducting coil and a heater placed near the superconducting wire). a superconducting coil power supply that is provided outside the cryogenic container and supplies current to the current loop, and a heater power supply that supplies current to the heater, thereby giving the current loop a predetermined size. In a superconducting device that creates a persistent current loop by circulating a current, when starting up the coil current already flowing in the superconducting coil, the power supply current is made equal to the magnitude of the coil current, and then the heater is energized. After bringing the superconducting wire into a normal conducting state,
The output current of the superconducting coil power supply is controlled so that the coil current increases to the final target value at a current increase rate that does not cause a quench accident in the superconducting coil, and in the process of increasing the coil current, the superconducting wire The heater is turned off for a period during which the normal conductivity state can be maintained due to Joule heat generation of R: a current reduction rate that does not cause a quench accident of the superconducting wire after the output current I_1 of the superconducting coil power source becomes equal to the coil current by turning on for a desired time calculated from (resistance of the superconducting wire) A control method for a superconducting device in which the power supply current is reduced to a zero value and the operation of the power supply for the superconducting coil is stopped. (6) A persistent current switch that is installed in the cryogenic container and forms a current loop together with the superconducting coil (this persistent current switch is connected to a superconducting wire connected in parallel to the superconducting coil and a heater placed near the superconducting wire). a superconducting coil power supply that is provided outside the cryogenic container and supplies current to the current loop, and a heater power supply that supplies current to the heater, thereby giving the current loop a predetermined size. In a superconducting device that creates a persistent current loop by causing a current to flow through the superconducting coil, when stopping the coil current already flowing in the superconducting coil, the power supply current is made equal to the magnitude of the coil current, and then the heater is energized. After bringing the superconducting wire into a normal conducting state,
The output current of the superconducting coil power source is controlled so that the coil current is reduced to the final target value at a current reduction rate that does not cause a quench accident in the superconducting coil, and in the process of decreasing the coil current, the superconducting wire The heater is turned off for a period during which the normal conductivity state can be maintained due to Joule heat generation of R: a current reduction rate that does not cause a quench accident of the superconducting wire after the output current I_1 of the superconducting coil power source becomes equal to the coil current by turning on for a desired time calculated from (resistance of the superconducting wire) A control method for a superconducting device in which the power supply current is reduced to a zero value and the operation of the power supply for the superconducting coil is stopped. (7) Claims 2 and 4 of the superconducting device characterized in that the heater is turned on again when the coil current becomes a value smaller than the final target value by a predetermined value. Control method. (8) In claims 1 to 6, in the section where only the power supply current is changed without changing the superconducting coil current, the current is changed at a faster rate of change than the section where the superconducting coil current I_3 is changed. 1. A method for controlling a superconducting device. (9) A method for controlling a superconducting device according to claim 3, wherein the final target value of the coil current is zero or a value other than zero.