JP6983629B2 - How to operate the superconducting magnet device and the superconducting magnet device - Google Patents

Description

An embodiment of the present invention relates to an operation technique of a superconducting magnet device capable of operating in a permanent current mode.

Conventionally, in a superconducting magnet device, there is a possibility that a quench may occur in which the superconducting state suddenly disappears. In order to operate this superconducting magnet device stably, the idea was to raise the temperature of the PCS (permanent current switch) when setting the permanent current mode, and then lower the temperature of the PCS to the temperature in the actual use state. be.

Japanese Unexamined Patent Publication No. 8-203723

In the above idea, since the temperature of the PCS is raised when the permanent current mode is set, there is a risk that quenching will occur when the temperature rises. In other words, the specific control content was not completed, and it was not a practical technology. Further, in recent years, with the spread of superconducting magnet devices, opportunities for long-term operation have increased, and the possibility of quenching during operation has increased. Therefore, there is a demand for a superconducting magnet device that can reduce the occurrence of quenching and operate stably.

An embodiment of the present invention has been made in consideration of such circumstances, and an object of the present invention is to provide an operation technique of a superconducting magnet device capable of reducing the occurrence of quenching and stably operating the device.

The method of operating the superconducting magnet device according to the embodiment of the present invention uses a heater to cool the superconducting coil and the permanent current switch using a cooling unit and transfer the superconducting current switch to superconducting, and to continue cooling by the cooling unit. The step of making the permanent current switch higher than the critical temperature and transferring it to normal conduction, the step of supplying current to the superconducting coil using the main power supply, and the step of controlling the heater to control the temperature of the permanent current switch. A step of starting to lower the current to a steady operation temperature lower than the critical temperature, and a step of starting to flow the current flowing through the superconducting coil to the permanent current switch by starting to lower the current supplied from the main power supply. include.

An embodiment of the present invention provides an operating technique for a superconducting magnet device capable of reducing the occurrence of quenching and stably operating the device.

The cross-sectional view which shows the superconducting magnet apparatus of this embodiment. The block diagram which shows the superconducting magnet apparatus of this embodiment. The circuit diagram which shows the superconducting magnet apparatus of this embodiment. A schematic diagram of the current density distribution of this embodiment and a cross-sectional view of a superconducting wire. Schematic diagram of current density distribution in the prior art and cross-sectional view of superconducting wire. The graph which shows the operation pattern of the superconducting magnet apparatus of this embodiment. The graph which shows the operation pattern of the superconducting magnet apparatus of the prior art. The graph which shows the operation pattern of the superconducting magnet apparatus of this embodiment. The graph which shows the operation pattern of the superconducting magnet apparatus of the prior art. The graph which shows the critical current value and the temperature of the superconducting wire material of this embodiment. The graph which shows the test result of the superconducting magnet apparatus of this embodiment. The schematic diagram which shows the superconducting coil and the permanent current switch of this embodiment. The figure which shows the permanent current switch of this Embodiment and a comparative example. The flowchart which shows the operation method of the superconducting magnet apparatus of this embodiment. The cross-sectional view which shows the modification of the superconducting magnet apparatus of this embodiment.

Hereinafter, this embodiment will be described with reference to the accompanying drawings. First, the superconducting magnet device of this embodiment will be described with reference to FIGS. 1 to 15. Reference numeral 1 in FIG. 1 is a superconducting magnet device that can be operated in the permanent current mode. The permanent current mode is an operation mode in which a circuit constituting the superconducting magnet device 1 forms a closed loop, and when this circuit is cooled and transferred to superconductivity, a current flows along the closed loop indefinitely. ..

As shown in FIG. 1, the superconducting magnet device 1 includes a superconducting coil 2 (main coil), a permanent current switch 3 that constitutes a superconducting circuit together with the superconducting coil 2, and a main power supply 4 that supplies power to the superconducting coil 2. , A cooling unit 5 for cooling the superconducting coil 2 and the permanent current switch 3, a conduction unit 6 connected to the superconducting coil 2 and the permanent current switch 3 to conduct heat to the cooling unit 5, and the superconducting coil 2 and the permanent current switch 3. A vacuum vessel 7 accommodating the current switch 3, a heater 8 for heating the permanent current switch 3, a heater power supply 9 for supplying power to the heater 8, a temperature sensor 10 for detecting the temperature of the permanent current switch 3, and a temperature sensor 10. A control device 11 for controlling each component and an analysis unit 12 for preliminarily analyzing the correspondence between the critical current and the temperature of the superconducting current used for the permanent current switch 3 are provided. In the following description, the permanent current switch may be abbreviated as PCS (Persistent Current Switch).

Inside the vacuum container 7, a radiation shield 21 for shielding heat transferred from the outside to the inside is provided. The superconducting coil 2 and the permanent current switch 3 are surrounded by a radiation shield 21. The radiation shield 21 is connected to the cooling unit 5 via the shielding unit 23.

The cooling unit 5 is provided with a first cooling stage 24 for cooling the radiation shield 21 and a second cooling stage 25 for cooling the superconducting coil 2 and the permanent current switch 3. Further, by cooling at the respective cooling stages 24 and 25, the superconducting coil 2 and the permanent current switch 3 are cooled to the assumed temperature. Further, by providing the radiation shield 21, it is possible to prevent the temperatures of the superconducting coil 2 and the permanent current switch 3 from rising due to heat radiation from the outside.

The superconducting magnet device 1 of the present embodiment exemplifies a conduction cooling system in which a superconducting coil 2, a permanent current switch 3, and a cooling unit 5 are thermally connected by a conduction unit 6. The conductive portion 6 is formed of a material exhibiting good thermal conductivity such as aluminum or copper. The cooling unit 5 is composed of a cryogenic refrigerator (GM refrigerator or the like). Since the cooling unit 5 is a conduction cooling type, a refrigerant such as liquid helium is not required, so that the superconducting coil 2 and the permanent current switch 3 can be easily cooled. Further, since the permanent current switch 3 and the heater 8 are not immersed in liquid helium or the like, the temperature of the permanent current switch 3 reacts sensitively to the amount of heat input of the heater 8 when the permanent current switch 3 is heated.

Next, the system configuration of the superconducting magnet device 1 will be described with reference to the block diagram shown in FIG. As shown in FIG. 2, the control device 11 includes a main control unit 13 that controls each component in an integrated manner, a main power supply control unit 14 that controls the main power supply 4, and a permanent current switch at the start of the permanent current mode. The temperature control unit 15 that controls the temperature of 3, the heater control unit 16 that controls the heater power supply 9, the cooling control unit 17 that controls the cooling unit 5, and the temperature of the permanent current switch 3 are controlled at the start of the permanent current mode. It is provided with a setting storage unit 18 for storing temperature control settings for monitoring, and a time measuring unit 19 (RTC: Real-Time Clock) for measuring the passage of time.

Further, the analysis unit 12 analyzes in advance the correspondence between the critical current and the temperature of the superconducting wire used for the permanent current switch 3, and determines the temperature control setting. Various data such as the material of the superconducting wire used for the permanent current switch 3 are input to the analysis unit 12. The correspondence between the critical current and the temperature of the superconducting wire used for the permanent current switch 3 may be obtained by an experiment (actual measurement). Further, this correspondence may be obtained by analyzing (calculating) the experimental results.

The control device 11 of the present embodiment has hardware resources such as a CPU, ROM, RAM, and HDD, and the CPU executes various programs to realize information processing by software using the hardware resources. Consists of. Further, the operation method of the superconducting magnet device 1 of the present embodiment is realized by causing a computer to execute a program.

The superconducting coil 2 and the permanent current switch 3 are coils in which a superconducting wire (winding wire) having a conductor of a superconducting material is wound. As shown in FIG. 3, both ends of the permanent current switch 3 are connected to both ends of the superconducting coil 2. That is, the superconducting coil 2 and the permanent current switch 3 form a parallel circuit. Then, in the permanent current mode, the closed loop L (permanent current coil) is formed by the superconducting coil 2 and the permanent current switch 3.

Further, the heater 8 may have any configuration as long as the heat can be transferred to the permanent current switch 3. For example, a film-shaped heater, a heating wire-shaped heater, or the like can be mentioned. When a film-shaped heater is used, it is desirable to bond the heater 8 to the surface of the permanent current switch 3 or to insert and bond the heater 8 between layers of the superwire material constituting the permanent current switch 3. When a heating wire-shaped heater is used, it is desirable to wind the heating wire around the surface of the permanent current switch 3 or to co-wound the heating wire along the superconducting wire material constituting the permanent current switch 3.

Further, the conductor of the superconducting material can flow a current in a state where the electric resistance is zero (superconducting state) in an environment where the three conditions of the critical temperature or less, the critical magnetic field or less, and the critical current or less are satisfied. Therefore, when a current is passed through the closed loop L formed by the superconducting coil 2 and the permanent current switch 3 in a state where the electric resistance is zero, the current can be maintained at a substantially constant value with almost no attenuation. Further, since the current flowing in the closed loop L is less likely to fluctuate, it is possible to continue to generate a constant magnetic field having extremely high stability. Such superconducting technology is applied to, for example, medical MRI requiring high magnetic field stability of 0.1 ppm / h or less, NMR for molecular structure analysis, and the like.

Further, the permanent current switch 3 can switch between a normal conduction state (OFF state) with high electric resistance and a superconducting state (ON state) with zero electric resistance. Here, when the permanent current switch 3 is turned on, the operation in the permanent current mode becomes possible in the closed loop L between the superconducting coil 2 and the permanent current switch 3. On the other hand, when the permanent current switch 3 is turned off, the operation of the permanent current mode in the closed loop L becomes impossible due to the high electric resistance of the permanent current switch 3. The permanent current switch 3 is turned off in order to reduce the amount of heat input when the permanent current switch 3 is changed from the ON state to the OFF state and to reduce the cooling time required when the permanent current switch 3 is changed from the OFF state to the ON state. In the state, it is desirable to generate high electrical resistance with as little conductor as possible.

The superconducting wire (winding) of the permanent current switch 3 is composed of a plurality of superconducting filaments and a base material (stabilizing material) around these superconducting filaments. The superconducting filament is generally formed of NbTi, but may be a superconducting material other than NbTi such as _{Nb 3} Sn and MgB _2. The base material is generally formed of high-resistance CuNi, but other copper alloys or high-resistance metals may be used. For example, when the temperature of the permanent current switch 3 is cooled to a critical temperature (superconducting transition temperature) or lower to bring it into a superconducting state, the electric resistance of each superconducting filament becomes zero, and current continues to flow through these superconducting filaments. On the other hand, when the temperature of the permanent current switch 3 is set higher than the critical temperature to bring it into a normal conduction state, high electric resistance is generated. The superconducting coil 2 can be excited by the electric resistance of the permanent current switch 3.

The permanent current switch 3 formed of CuNi as a base material is less stable than the case where a low electric resistance metal such as copper is used as a base material. For example, in the permanent current switch 3, quenching may occur due to a small disturbance (fluctuation) such as a slight change in temperature or a change in current density due to the state of the cooling unit 5.

A state in which a current corresponding to the critical current density is flowing through the superconducting filament is referred to as a saturated state and will be described below. Further, in the cross-sectional view of the superconducting wire, the region where the superconducting filament in which the current is flowing exists is referred to as an energized region and will be described below.

Quenching is likely to occur if a saturated superconducting filament is present in the permanent current switch 3 during operation in the permanent mode. Therefore, in the present embodiment, in order to prevent the occurrence of quenching, the temperature of the permanent current switch 3 is lowered while being controlled at the start of the permanent current mode. The temperature of the permanent current switch 3 is controlled by the heater 8. The heater 8 is supplied with a current from a heater power supply 9 different from that of the main power supply 4. Further, after the temperature of the permanent current switch 3 is monotonically decreased, the temperature is controlled to be the steady operating temperature.

Here, the steady operation temperature is a normal temperature when the superconducting magnet device 1 is operated in the permanent current mode, and is when the superconducting coil 2 and the permanent current switch 3 are cooled by using the cooling unit 5. This is the target temperature. By maintaining this steady operating temperature, the superconducting magnet device 1 is operated for a long time in the permanent current mode. The steady-state operating temperature is not always a constant value, but is a value that may fluctuate slightly up and down depending on an external factor or an operating mode. Further, the fluctuation range of the steady operating temperature is within the predicted range. Further, the minimum value and the maximum value of the fluctuation range of the steady operating temperature can be specified in advance by various configurations such as the current value flowing through the superconducting coil 2 and the permanent current switch 3, the material of the conductor, and the conductor length.

Further, in the present embodiment, at the start of the permanent current mode, the current flowing through the permanent current switch 3 is controlled and increased. The current flowing through the permanent current switch 3 is controlled by the amount of current supplied by the main power supply 4. For example, when the superconducting coil 2 and the permanent current switch 3 are cooled to the critical temperature or lower and the current is supplied from the main power supply 4 to the superconducting coil 2, the current supplied from the main power supply 4 is reduced. Then, the current flowing through the permanent current switch 3 increases with this decrease.

In the present embodiment, the temperature of the permanent current switch 3 is lowered at a rate of decrease (ratio) corresponding to the rate of increase of the current flowing through the permanent current switch 3. Further, before the start of operation (at the time of manufacture) of the superconducting magnet device 1, the correspondence relationship between the critical current value and the temperature of the superconducting wire material of the permanent current switch 3 is obtained by experiment or analysis in advance. Based on this obtained correspondence, the rate of increase in current and the rate of decrease in temperature of the permanent current switch 3 at the start of the permanent current mode are controlled. For example, control is performed to increase the current flowing through the permanent current switch 3 within a range not exceeding the critical current value that increases in response to the decrease in the temperature of the permanent current switch 3.

By doing so, it is possible to set the rate of increase in current and the rate of decrease in temperature suitable for the correspondence between the critical current value of the permanent current switch 3 and the temperature. Further, since the current flowing through the permanent current switch 3 does not exceed the critical current value, it is possible to reduce the occurrence of quenching at the start (transition) of the permanent current mode.

Next, the operation method of the superconducting magnet device 1 of the present embodiment will be described with reference to FIGS. 4 to 11. In addition, in order to help understanding, the present embodiment and the prior art will be compared and described. 4, FIG. 6 and FIG. 8 are views relating to the superconducting magnet device 1 of the present embodiment. FIGS. 5, 7, and 9 corresponding to these figures are views relating to the superconducting magnet device of the prior art.

The figures on the left side of FIGS. 4 and 5 are graphs showing the distribution of the current density J of the superconducting wire of the permanent current switch 3. The figures on the right side of FIGS. 4 and 5 are cross-sectional views of the superconducting wire of the permanent current switch 3. The cross-sectional view of these superconducting wires is a schematic view omitting the illustration of a plurality of superconducting filaments and a base material around them.

6 (A) and 7 (A) are graphs showing the output of the heater 8 (the value of the current output from the heater power supply 9). 6 (B) and 7 (B) are graphs showing the temperature of the permanent current switch 3 (PCS temperature T). 6 (C) and 7 (C) are graphs showing the value of the current output from the main power supply 4 (power supply output value I _OP). 6 (D) and 7 (D) are graphs showing the values of the current flowing through the superconducting coil 2 (superconducting coil current value _Im). FIG 6 (E) and FIG. 7 (E) is a graph showing the value of the current flowing through the permanent current switch 3 (PCS current value _{I t).}

8 (A) and 9 (A) are graphs showing the PCS temperature T when approaching steady operation. Figure 8 (B) and FIG. 9 (B) is a graph showing the critical current value I _C of the superconducting wire of the permanent current switch 3. Figure 8 (C) and FIG. 9 (C) is a graph showing the PCS current value _{I t.} Figure 8 (D) and FIG. 9 (D) is a graph showing the superconducting wire of the load factor of the permanent current switch 3 _(I t / I _c). Figure 8 (E) and FIG. 9 (E) is a graph showing the current increase rate of the permanent current switch _{3 (dI t / dI c)} .

In each graph of FIGS. 6 to 9, the horizontal axis is time t. In these graphs, t1 is the timing when the permanent current switch 3 is turned off. t2 is the timing at which the supply of current from the main power supply 4 to the superconducting coil 2 is started. t3 is the timing at which the value of the current flowing through the superconducting coil 2 becomes maximum. t4 is the timing at which the temperature of the permanent current switch 3 starts to be lowered. t5 is the timing at which the current starts to flow through the permanent current switch 3. t6 is the timing at which the current flowing through the permanent current switch 3 reaches the value during steady operation. t7 is the timing when the permanent current switch 3 reaches the steady operating temperature. T1 is the steady operating temperature of the permanent current switch 3. T2 is the temperature at which the current flowing through the permanent current switch 3 reaches the value at the time of steady operation. T3 is the critical temperature of the permanent current switch 3. T4 is the temperature of the permanent current switch 3 in the OFF state. Z is the maximum value of the current increase rate of the permanent current switch 3.

As shown in FIG. 6, when starting the operation of the superconducting magnet device 1 of the present embodiment, first, with the outputs of the main power supply 4 and the heater power supply 9 stopped, the superconducting coil 2 and the permanent superconducting coil 2 are used by the cooling unit 5. Cool the current switch 3. Here, the cooled superconducting coil 2 and the permanent current switch 3 have a steady operating temperature T1 which is a temperature equal to or lower than the critical temperature T3, and are transferred to superconductivity.

Next, a current is supplied from the heater power supply 9 to the heater 8, and the heating of the permanent current switch 3 is started by the heater 8. The temperature of the permanent current switch 3 rises as the output (current value) of the heater power supply 9 rises.

At the time t1 of FIG. 6, the output value of the heater power supply 9 immediately reaches the maximum value. On the other hand, the temperature of the permanent current switch 3 gradually rises. Then, at time t2, the temperature of the permanent current switch 3 exceeds the critical temperature T3. Here, the permanent current switch 3 is transferred to the normal conduction state (OFF state).

At the time t2 of FIG. 6, the supply of current from the main power supply 4 to the superconducting coil 2 is started. Here, the superconducting coil current value I _m is increased with an increase in the power output value I _OP. Even if the current supply of the main power supply 4 is started, the permanent current switch 3 is in the normal conduction state, so that the current flowing through the permanent current switch 3 is small, and most of the current supplied from the main power supply 4 is the superconducting coil 2. Flow to. Then, the power supply output value I _OP and the superconducting coil current value _Im become the maximum values, and the permanent current switch 3 becomes the temperature T4 exceeding the critical temperature T3, and these states are temporarily maintained.

At the time t4 of FIG. 6, the output value of the heater power supply 9 starts to decrease, and the temperature of the permanent current switch 3 starts to decrease. In the present embodiment, the temperature of the permanent current switch 3 is gradually lowered by gradually lowering the output value of the heater power supply 9. The rate of decrease in the PCS temperature does not have to be constant. That is, it is not necessary that the passage of time and the decrease in PCS temperature are proportional to each other. Further, the rate of decrease in the PCS temperature may be changed on the way. Note that FIG. 6 illustrates a graph in which the passage of time and the decrease in PCS temperature are proportional (a graph that tilts linearly from time t4 to time t7).

At the time t5 of FIG. 6, the current supplied from the main power supply 4 starts to be lowered at the timing during the temperature drop of the permanent current switch 3 and at the timing when the temperature of the permanent current switch 3 becomes the critical temperature T3 or less. .. Here, PCS current value _{I t} with a decrease in the power output value _{I OP} starts to rise. That is, the increase in the current flowing through the permanent current switch 3 is started. Then, the closed loop L (see FIG. 3) begins to be formed by the superconducting coil 2 and the permanent current switch 3. In the present embodiment, the rate of increase of the current flowing through the permanent current switch 3 is controlled by controlling the output value of the main power supply 4. Further, by controlling the output value of the heater power supply 9, the rate of decrease in the temperature of the permanent current switch 3 is controlled.

At the time t6 of FIG. 6, the value of the current supplied from the main power supply 4 becomes zero at the timing during the temperature drop of the permanent current switch 3. That is, the main power supply 4 is stopped. Here, the closed loop L (see FIG. 3) is completed by the superconducting coil 2 and the permanent current switch 3. At this time t6, the current flowing through the permanent current switch 3 becomes the value at the time of steady operation. The temperature of the permanent current switch 3 is further lowered.

At time t7 in FIG. 6, the value of the current supplied from the heater power supply 9 becomes zero. That is, the heater power supply 9 is stopped. Here, the temperature of the permanent current switch 3 becomes the steady operation temperature T1. In this state, steady operation of the superconducting magnet device 1 of the present embodiment is started.

In the present embodiment, the temperature of the permanent current switch 3 is lowered while being controlled during the period from time t4 to time t7. By doing so, the occurrence of quenching can be reduced and stable operation can be performed.

On the other hand, in the prior art, the operation pattern in the period from the time t4 to the time t6 (t7) is different. In the prior art, the time t6 at which the current flowing through the permanent current switch 3 reaches the value during steady operation and the time t7 at which the permanent current switch 3 reaches the steady operating temperature coincide with each other.

For example, as shown in FIG. 7, in the prior art, the output value of the heater power supply 9 is sharply lowered at time t4. This is a control in which the heater power supply 9 is simply turned from ON to OFF at time t4. Therefore, the temperature of the permanent current switch 3 also drops sharply. Here, the temperature of the permanent current switch 3 becomes the steady operation temperature T1.

At the time t5 of FIG. 7, the current supplied from the main power supply 4 starts to be reduced while the temperature of the permanent current switch 3 has already dropped to the steady operating temperature T1. Here, PCS current value _{I t} with a decrease in the power output value _{I OP} starts to rise. That is, the increase in the current flowing through the permanent current switch 3 is started.

At the time t6 (t7) of FIG. 7, the value of the current supplied from the main power supply 4 becomes zero. That is, the main power supply 4 is stopped. Here, the closed loop L (see FIG. 3) is completed by the superconducting coil 2 and the permanent current switch 3.

In the prior art, immediately after the time t4, the temperature of the permanent current switch 3 is rapidly lowered to reach the steady operation temperature T1. Then, after that, the increase of the current flowing through the permanent current switch 3 is started. In the interior of the superconducting wire of the permanent current switch 3, electric current begins to flow in the critical current density J _C from the outer peripheral portion side of the superconducting wire by self-field effect. That is, the energization region S (saturation region) begins to form from the outer peripheral side of the superconducting wire.

Here, in the prior art, how to expand the energization region S inside the superconducting wire material of the permanent current switch 3 will be described with reference to FIG. FIG. 5A shows a state in which a current starts to flow in the superconducting wire (for example, a state at time t5). FIG. 5B shows a state in which the current is in the process of increasing in the superconducting wire (for example, a state between time t5 and time t6). FIG. 5C shows a state in which the current flowing through the superconducting wire has reached the value during steady operation (for example, a state at time t6).

In the prior art, when a current starts to flow through the superconducting wire of the permanent current switch 3, the energized region S starts to expand from the outer peripheral Q to the center P in the cross-sectional view of the superconducting wire (FIG. 5A). The superconducting wire material of the permanent current switch 3 has already reached the steady operating temperature T1 before the current starts to flow. Therefore, the critical current density _JC does not change, and only the current flowing through the superconducting wire increases. Then, as the current increases, the energized region S expands from the outer peripheral Q to the center P (FIGS. 5 (B) and 5 (C)).

If there is an energized region S in which a current is flowing at the critical current density _JC , the positive feedback "movement of the magnetic flux that has entered the inside of the superconductor-temperature rise due to the movement of the magnetic flux-criticality of the superconductor" It becomes a state of "decrease in current density-further intrusion of magnetic flux", causing a continuous spontaneous temperature rise, and the possibility of quenching (magnetic instability) increases. In particular, as in the prior art, in the critical current density J _C does not change, when the electrically conducting region S is widened, there is a problem that it is easy quench occurs.

Next, in the present embodiment, how to expand the energization region S inside the superconducting wire material of the permanent current switch 3 will be described with reference to FIG. FIG. 4A shows a state in which a current starts to flow in the superconducting wire (for example, a state at time t5). FIG. 4B shows a state in which the current is in the process of increasing in the superconducting wire (for example, a state between time t5 and time t6). FIG. 4C shows a state in which the current flowing through the superconducting wire has reached the value during steady operation (for example, a state at time t6).

In the present embodiment, a wide energization region S is secured from the beginning. For example, the inner radius of the energized region S can be obtained by the following formula 1.
(Formula 1)
_{r S = r W × [1-} (I t / I C)] 0.5
Here, _{r S} is the inner radius, _{r W} energization region S, the radius of the superconducting wire, _{I t} is PCS current, _{I C} is the critical current value of a superconducting wire.

According to this equation 1, when the critical current density _JC is low, that is, immediately after the temperature of the permanent current switch 3 starts to drop, a current is started to flow through the permanent current switch 3, so that the inner radius r _S of the energization region S is obtained. It turns out that it can be made smaller. That is, in the cross-sectional view of the superconducting wire, a wide area of energization region S can be secured, and the current can be conducted using this wide effective area (FIG. 4A). _{The critical current density JC} is increased by lowering the temperature of the permanent current switch 3 in a state where the energization region S having a large area is secured (FIGS. 4B and 4C).

By critical current density J _C is increased, it is possible to realize a state where there is room for energizing area S (conduction region) does not reach the critical current density J _C. Yuku increase the PCS current value I _m corresponding to the portion where there is the margin. This reduces the magnetic instability of the superconducting wire. Then, the probability that the permanent current switch 3 causes quenching can be reduced, and the superconducting magnet device 1 can be shifted to the permanent current mode in a stable state.

_{In the present embodiment, the correspondence between the critical current density JC} and the temperature of the superconducting wire material of the permanent current switch 3 is obtained in advance by experiment or analysis. Here, as a typical example of the superconducting characteristics of the superconducting filament of NbTi, which is the base material of CuNi, at a temperature of 4.2 K (Kelvin), a magnetic flux density of 1 T (Tesla), and a wire diameter of about 1 mm having _{I c = 1000 A.} , A superconducting wire with a copper ratio of around 1 is assumed. As shown in the graph of FIG. 10, the temperature dependence of the superconducting characteristics of the NbTi superconducting filament can be calculated by linearly approximating the temperature. Therefore, it is possible to obtain the PCS current value I _t of the superconducting wire at a given PCS temperature T, approximately.

The acquisition of this correspondence is carried out by the analysis section 12, the temperature control set containing increasing rate and decreasing rate of the PCS temperature T of the PCS current value I _t is determined. Then, the determined temperature control setting is stored in the setting storage unit 18 (see FIG. 2). Furthermore, the temperature and time measuring unit 19 of the permanent current switch 3 is detected (superconducting wire) is based on the time counting by the temperature sensor 10, the increase rate and decrease rate of the PCS temperature T of the PCS current value I _t is controlled .. Also, PCS temperature T is fed back to the control of the control and heater 8 for PCS current value _{I t.}

By doing so, it is possible to appropriately control the increase and decrease of the current of the permanent current switch 3 based on the temperature of the permanent current switch 3 detected in real time. Incidentally, the rate of increase in PCS current value _{I t} corresponds to the reduction rate of the power supply output value _{I OP.} In other words, the output of the main power supply 4 is controlled, PCS current value I _t is controlled. Further, the rate of decrease in the PCS temperature T is controlled by the output of the heater power supply 9.

Next, the superconducting wire of the load factor of the permanent current switch 3 from time t5 of the present embodiment to the time t6 _(I t / I _c) and current increase rate _(dI t / dI _c) shown in the graph of FIG. Here, the maximum value Z of the current increase rate of the superconducting wire is smaller than 1 (less than 1). In other words, the maximum value Z of the current increase rate of the superconducting wire _(dI t / dI _c) is to be no greater than 1, and controls the PCS current value _{I t.}

That is, in this embodiment, the value of the current flowing through the permanent current switch 3 at time t and I _{t (t),} the temperature of the permanent current switch 3 at time t and T (t), the persistent current switch at the temperature T the value of the critical current in the case of the _I C (T), when lowering the temperature of the permanent current switch _{3, I t (t) <} I C to (t), the and the time rate of change _(dI t / dI _C ) ≤ 1 is controlled.

By doing so, the temperature of the permanent current switch 3 can be lowered so that the current flowing through the permanent current switch 3 _{does not exceed the critical current density JC.} Further, the current density distribution when the energization region S is formed inward from the outer peripheral Q of the superconducting wire does not change immediately even if the temperature of the superconducting wire is subsequently lowered. Therefore, without increasing the inner with a radius r _S of energizing area S to the inside, by increasing the PCS current value I _t, to continue the state that does not reach energizing area S (the conduction region) the critical current density J _C be able to. This can reduce the probability of quenching.

Meanwhile, in the prior art, as shown in the graph of FIG 9, the maximum value Z of the current increase rate of the superconducting wire of the permanent current switch 3 _(dI t / dI _c) is in the 6 or more. This conventional technique has a problem that the probability of occurrence of quenching increases, but in the present embodiment, such a problem can be solved.

Incidentally, when the time rate of change of the PCS current value I _t is extremely large, it occurs the heat by AC loss of the superconducting wire. Therefore, in this embodiment, for example, in the case of increasing per minute 20A the PCS current value I _t, cooled per minute 1K speeds less than the temperature of the permanent current switch 3. By doing so, the temperature of the permanent current switch 3 is lowered at a slow rate of decrease of 1 K or less per minute, so that the occurrence of quenching can be reduced. Further, it is possible to maintain with respect to the current density J of the current region S, a state where a relatively high and the critical current density J _C of that portion.

In the present embodiment, as shown in the graph of FIG. 8, at the timing of time t6 before the time t7 when the temperature of the permanent current switch 3 reaches a steady operating temperature T1, PCS current value I _t is the time of steady operation It becomes a value (maximum value). That is, the supply of current by the main power supply 4 is stopped. In the present embodiment, with respect to normal operating temperature T1, PCS current value I _t is controlled to be higher the temperature T2 at which a value of the steady operation. By doing so, the temperature of the permanent current switch 3 can be further lowered after the current flowing through the permanent current switch 3 reaches the value at the time of steady operation.

Against the prior art, as shown in the graph of FIG. 9, the time t7 when the temperature of the permanent current switch 3 reaches a steady operating temperature T1 is, PCS current value I _t is the time of steady operation value (maximum value) It coincides with the time t6. In this case, quenching is likely to occur.

In the present embodiment, the temperature T2 of the permanent current switch 3 when the current flowing through the permanent current switch 3 reaches the value at the time of steady operation is further lowered by 0.3 K or more to shift to steady operation. In this way, there is a margin in the current flowing through the permanent current switch 3 during steady operation, so that quenching is less likely to occur even if the temperature of the permanent current switch 3 fluctuates during operation in the permanent current mode. ..

The temperature difference between the temperature T2 and the steady operating temperature T1 of the permanent current switch 3 when the PCS current value I _t becomes equal to the steady-state operation and (T2-T1), the time t _Q until quenching occurs The results of the relationship test are shown in the graph of FIG. The black dots in the graph of FIG. 11 are plotted based on the test results. Then, a line approximately obtained for the temperature difference and the quench generation time is shown. As can be estimated from this line, it can be seen that the time until quench occurs increases as the temperature difference increases.

In the superconducting magnet device 1, it is necessary to perform maintenance at a frequency of about one year, that is, every 10,000 hours. Therefore, it is desirable to be able to operate stably until the operation is interrupted every 10,000 hours. Referring to the graph of FIG. 11, 10,000 hours is achieved with a temperature difference (T2-T1) of about 0.36K. That is, if there is a temperature difference of 0.3 K or more, the substantially required operating time can be satisfied. This temperature difference may be 1K or more, or may be increased within a range not exceeding the critical temperature of the permanent current switch 3.

The temperature T2 of the permanent current switch 3 when the PCS current value I _t becomes equal to the steady-state operation has become a higher temperature than the maximum value of the variation range of the steady operating temperature. By doing so, even if the temperature of the permanent current switch 3 fluctuates during the steady operation, the superconducting wire material does not become saturated.

Further, in the present embodiment, as shown in FIG. 6, the current flowing through the permanent current switch 3 starts to increase more than the period from the start of the temperature decrease of the permanent current switch 3 (t4) to the completion of the decrease (t7). The period from the hour (t5) to the completion of the increase (t6) is shortened. By doing so, since the period in which the temperature of the permanent current switch 3 fluctuates is longer than the period in which the current flowing through the permanent current switch 3 fluctuates, it is possible to provide a margin for controlling the current of the permanent current switch 3. .. That is, it is possible to suppress the occurrence of quenching in the vicinity of the time when the increase of the current starts (t5) or the time when the increase is completed (t6).

Next, the arrangement of the permanent current switch 3 of the present embodiment will be described with reference to FIGS. 12 and 13. FIG. 12 is a diagram showing an arrangement of the superconducting coil 2 and the permanent current switch 3 of the present embodiment. FIG. 13A is a diagram showing the relationship between the permanent current switch 3 and the magnetic field line M according to the present embodiment. FIG. 13B is a diagram showing the relationship between the permanent current switch 3 and the magnetic field line M in the comparative example (bad example).

As shown in FIG. 12, the superconducting coil 2 and the permanent current switch 3 form a cylinder in which the corresponding superconducting wires are wound. The permanent current switch 3 is a coil smaller than the superconducting coil 2. The permanent current switch 3 is arranged in the vicinity of the superconducting coil 2.

The permanent current switch 3 is a non-inductive winding coil. For example, one long superconducting wire is bent at an intermediate portion and then wound. Therefore, in the wound state, the currents flowing through the adjacent superconducting wires are in opposite directions to each other, so that the mutual inductances cancel each other out, resulting in a non-inductive coil without magnetic poles.

In the present embodiment, the direction in which the axis X1 of the cylinder of the superconducting coil 2 extends and the direction in which the axis X2 of the cylinder of the permanent current switch 3 extends are the same direction. That is, the shaft X1 of the superconducting coil 2 and the shaft X2 of the permanent current switch 3 are parallel to each other. Further, in the axial direction, the permanent current switch 3 is arranged at the center position V of the superconducting coil 2. That is, the permanent current switch 3 is arranged at the center position V of the N pole and the S pole of the superconducting coil 2. The center position V of the superconducting coil 2 and the permanent current switch 3 coincide with each other.

The magnetic field line M (leakage magnetic field) generated from the superconducting coil 2 passes through the permanent current switch 3. In the present embodiment, the permanent current switch 3 is arranged in a state where the direction in which the axis X2 of the permanent current switch 3 extends coincides with the direction in which the magnetic field line M generated from the superconducting coil 2 flows. That is, the permanent current switch 3 is arranged so that the vertical component is larger than the horizontal component of the leakage magnetic field of the superconducting coil 2.

In this way, the magnetic field line M of the superconducting coil 2 passes from the direction perpendicular to the direction in which the superconducting wire extends, regardless of the part of the superconducting wire wound in the circumferential direction of the permanent current switch 3. Therefore, the influence of the magnetic field on the superconducting wire can be made uniform in each part. Therefore, the generation of quenching can be reduced by the permanent current switch 3.

For example, as shown in FIG. 13A, the permanent current switch 3 will be described evenly divided into four regions A to D in the circumferential direction. When the direction in which the axis X2 of the permanent current switch 3 extends coincides with the direction in which the lines of magnetic force M generated from the superconducting coil 2 flow, the lines of magnetic force are perpendicular to the direction in which the superconducting wires in the four regions A to D extend. M passes. Therefore, the influence of the superconducting wire material of the permanent current switch 3 on the magnetic field lines M is substantially the same in the four regions A to D. Therefore, stable operation can be performed by eliminating the magnetic instability caused by the distribution of the magnetic field.

On the other hand, as shown in FIG. 13B, when the direction in which the axis X2'of the permanent current switch 3 extends is perpendicular to the direction in which the magnetic field line M generated from the superconducting coil 2 flows, in the regions B and D, The magnetic field lines M pass in a direction substantially perpendicular to the direction in which the superconducting wire is extended, but in the regions A and C, the magnetic force lines M pass in substantially the same direction as the direction in which the superconducting wire is extended. Therefore, the influence of the superconducting wire material of the permanent current switch 3 on the magnetic field line M is different between the region B and the region D and the region A and the region C. In such a case, there is a problem that the probability that quenching occurs due to the fluctuation of the magnetic field line M increases, but in the present embodiment, such a problem can be solved.

Next, the operation method of the superconducting magnet device 1 will be described with reference to the flowchart of FIG. The block diagram shown in FIG. 2 will be referred to as appropriate. In the description of each step in the following flowchart, for example, the part described as "step S11" is abbreviated as "S11".

As shown in FIG. 14, first, various data such as the material of the superconducting wire material of the permanent current switch 3 are input to the analysis unit 12. The analyzer 12 analyzes the relationship between the critical current density J _C and the temperature T of the superconducting wire (S11). The correspondence obtained by the experiment may be input to the analysis unit 12. The acquired correspondence determines the temperature control setting for controlling the temperature of the permanent current switch 3 at the start of the permanent current mode. Then, the temperature control setting output from the analysis unit 12 is input to the control device 11.

Next, the setting storage unit 18 of the control device 11 stores the temperature control setting determined by the analysis unit 12 (S12). Next, the cooling control unit 17 starts cooling the superconducting coil 2 and the permanent current switch 3 by starting the operation of the cooling unit 5 (S13). When cooling is started, the superconducting coil 2 and the permanent current switch 3 are cooled to the steady operating temperature T1 and transferred to the superconducting state.

Next, the heater control unit 16 starts the operation of the heater 8 while the cooling by the cooling unit 5 is continued. Then, the heater control unit 16 heats the permanent current switch 3 using the heater 8 to a temperature higher than the critical temperature T3. Then, the permanent current switch 3 is transferred to the normal conduction state (OFF state) of high electric resistance (S14).

Next, the main power supply control unit 14 controls the main power supply 4 to start current supply, and starts to flow a current through the superconducting coil 2 (S15). Then, the current flowing through the superconducting coil 2 becomes the value at the time of steady operation.

Next, the heater control unit 16 controls the heater power supply 9 to adjust the output of the heater 8 to start lowering the temperature of the permanent current switch 3 toward the steady operation temperature T1 lower than the critical temperature T3 (S16). ). Here, when the temperature of the permanent current switch 3 becomes equal to or lower than the critical temperature T3, the permanent current switch 3 is transferred to the superconducting state (ON state) without electrical resistance.

Next, the temperature control unit 15 controls the temperature decrease rate of the permanent current switch 3 based on the temperature control setting stored in the setting storage unit 18 (S17). The control of this decrease rate is performed according to the temperature of the permanent current switch 3 detected by the temperature sensor 10. Further, the heater control unit 16 controls the output of the heater 8 according to the rate of decrease in temperature.

Next, the main power supply control unit 14 controls the main power supply 4 to start reducing the current supply amount (S18). Then, the current flowing through the permanent current switch 3 begins to increase in response to the decrease in the amount of current supplied by the main power supply 4.

Next, the main power supply control unit 14 controls to adjust the rate of decrease in the amount of current supplied by the main power supply 4 (S19). Here, the main power supply control unit 14 controls to increase the current flowing through the permanent current switch 3 within a range not exceeding the critical current that increases in response to the decrease in the temperature of the permanent current switch 3. The main power supply control unit 14 controls the main power supply 4 in response to the rate of decrease in the temperature of the permanent current switch 3. Then, the temperature control unit 15 adjusts the temperature so that the temperature of the permanent current switch 3 decreases at a decrease rate corresponding to the increase rate of the current flowing through the permanent current switch 3.

Next, the value of the current supplied from the main power supply 4 becomes zero before the temperature of the permanent current switch 3 reaches the steady operation temperature T1. That is, the main power supply 4 is stopped (S20). Here, the current flowing through the permanent current switch 3 becomes the value at the time of steady operation. Further, the closed loop L is completed by the superconducting coil 2 and the permanent current switch 3, and the permanent current mode is started.

Next, the temperature of the permanent current switch 3 further decreases (S21). In this embodiment, the temperature of the permanent current switch 3 is lowered by 0.3 K or more from the temperature T2 when the main power supply 4 is stopped. Next, the heater control unit 16 stops the current supply by the heater power supply 9 and lowers the temperature of the permanent current switch 3 to the steady operation temperature T1 to start the steady operation (S22).

Although the flowchart of the present embodiment illustrates a mode in which each step is executed in series, the context of each step is not necessarily fixed, and even if the context of some steps is exchanged. good. Also, some steps may be executed in parallel with other steps.

The control device 11 of the present embodiment includes a control unit in which a dedicated chip, a controller such as an FPGA (Field Programmable Gate Array), a GPU (Graphics Processing Unit), or a CPU (Central Processing Unit) is highly integrated, and a ROM (ROM). Storage devices such as Read Only Memory) or RAM (Random Access Memory), external storage devices such as HDD (Hard Disk Drive) or SSD (Solid State Drive), display devices such as displays, and input such as mouse or keyboard. It is equipped with a device and a communication I / F, and can be realized by a hardware configuration using a normal computer.

The program executed by the control device 11 of the present embodiment is provided by incorporating it into a ROM or the like in advance. Alternatively, the program may be a non-transient storage medium such as a CD-ROM, CD-R, memory card, DVD, flexible disk (FD) that can be read by a computer in an installable or executable format file. It may be stored and provided in.

Further, the program executed by the control device 11 may be stored on a computer connected to a network such as the Internet, and may be downloaded and provided via the network. Further, the control device 11 can also be configured by connecting separate modules that independently exhibit the functions of the components to each other by a network or a dedicated line and combining them.

The superconducting coil 2 and the permanent current switch 3 do not have to be cooled by one cooling unit 5. For example, a plurality of cooling units may be provided, one for cooling the superconducting coil 2 and the other for cooling the permanent current switch 3.

In this embodiment, the conduction cooling method is exemplified as a method for cooling the superconducting coil 2 and the permanent current switch 3, but other embodiments may be used. For example, a helium cooling method using liquid helium as a refrigerant may be used. Further, a cooling method using liquid nitrogen may be used.

An impregnated cooling type superconducting magnet device 1A using a cryogenic liquid cooling medium (cooling unit) will be described with reference to a modification of FIG. The superconducting magnet device 1A closes the first vacuum heat insulating container 31, the second vacuum heat insulating container 32 arranged inside the first vacuum heat insulating container 31, and the upper opening of the first vacuum heat insulating container 31. 1 lid 33, a second lid 34 that closes the opening at the upper part of the second vacuum heat insulating container 32, a heat insulating member 35 provided at the lower part of the second lid 34, and the internal space of the second vacuum heat insulating container 32. A plurality of baffle plates 36 for preventing convection and a hanger 37 for suspending the superconducting coil 2 and the permanent current switch 3 from the second lid 34 are provided.

Liquid nitrogen 38 is housed inside the first vacuum heat insulating container 31. Further, the liquid helium 39 is housed inside the second vacuum heat insulating container 32. The superconducting coil 2 and the permanent current switch 3 are immersed in the liquid helium 39 inside the second vacuum insulation container 32. The liquid helium 39 cools the superconducting coil 2 and the permanent current switch 3 to the assumed temperature.

If the permanent current switch 3 is immersed in liquid helium or liquid nitrogen, it becomes difficult to detect the temperature of the permanent current switch 3 using a temperature sensor. Therefore, before actually starting the operation, the data when the temperature of the permanent current switch 3 immersed in liquid helium or liquid nitrogen is lowered while being controlled by the heater is acquired. Then, when actually operating, the heater is controlled at the time of transition to the permanent current mode based on the acquired data.

The critical temperature T3 of this embodiment is substantially the same as the current shunt temperature. The current diversion temperature is a temperature equal to or lower than the critical temperature of the material of the plurality of superconducting filaments included in the permanent current switch 3, and is a temperature at which the current shunted in each superconducting filament reaches the critical current density. The critical temperature (transition temperature) generally used in the superconducting technique is a temperature uniquely determined according to the physical properties of the superconducting material forming the superconducting filament, whereas the current diversion of the present embodiment is performed. The temperature is a temperature that is predetermined according to the value of the current supplied by the main power supply 4. That is, the current shunt temperature is a temperature that is appropriately changed according to the setting of the main power supply 4. In the above-described embodiment, various controls are performed based on the critical temperature T3, but various controls may be performed based on the current shunt temperature.

According to the embodiment described above, by lowering the temperature of the permanent current switch at a rate of decrease corresponding to the rate of increase of the current flowing through the permanent current switch, the occurrence of quenching can be reduced and stable operation can be performed.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other embodiments, and various omissions, replacements, changes, and combinations can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope of the invention described in the claims and the equivalent scope thereof, as are included in the scope and gist of the invention.

1 (1A) ... Superconducting magnet device, 2 ... Superconducting coil, 3 ... Permanent current switch, 4 ... Main power supply, 5 ... Cooling unit, 6 ... Conduction unit, 7 ... Vacuum container, 8 ... Heater, 9 ... Heater power supply, 10 ... Temperature sensor, 11 ... Control device, 12 ... Analysis unit, 13 ... Main control unit, 14 ... Main power supply control unit, 15 ... Temperature control unit, 16 ... Heater control unit, 17 ... Cooling control unit, 18 ... Setting storage unit , 19 ... Measuring part, 21 ... Radiation shield, 23 ... Shielding conduction part, 24 ... First cooling stage, 25 ... Second cooling stage, 31 ... First vacuum insulation container, 32 ... Second vacuum insulation container, 33 ... first lid, 34 ... second lid, 35 ... heat insulating member, 36 ... baffle plate, 37 ... load block, 38 ... liquid nitrogen, 39 ... liquid helium, I C _... critical current value of a superconducting wire, I m _... superconducting coil current value, I _{OP ...} power supply output _value, I t ... PCS current value, J ... current density, J C _... critical current density, L ... closed loop, M ... magnetic field lines, P ... center of the superconducting wire, Q ... outer periphery of the superconducting wire , R _S ... inner radius of the current-carrying region, r _W ... radius of the superconducting wire, S ... time, T ... PCS temperature, V ... center position of the superconducting coil, X1 ... shaft of the superconducting coil, X2 ... The axis of the permanent current switch of the embodiment, X2'... the axis of the permanent current switch of the comparative example, Z ... the maximum value of the current increase rate.

Claims (13)

The step of cooling the superconducting coil and the permanent current switch using the cooling unit and transferring them to superconductivity,
A step of using a heater to raise the permanent current switch to a temperature higher than the critical temperature and transferring it to normal conduction while continuing cooling by the cooling unit.
The step of supplying current to the superconducting coil using the main power supply,
A step of controlling the heater to start lowering the temperature of the permanent current switch toward a steady-state operating temperature lower than the critical temperature.
A step of starting to flow the current flowing through the superconducting coil to the permanent current switch by starting to reduce the current supplied from the main power supply.
How to operate a superconducting magnet device including. The method for operating a superconducting magnet device according to claim 1, further comprising a step of lowering the temperature of the permanent current switch at a decrease rate corresponding to an increase rate of a current flowing through the permanent current switch. Steps to obtain the correspondence between the critical current and temperature of the permanent current switch by experimenting or analyzing in advance, and
A step of increasing the current flowing through the permanent current switch within a range not exceeding the critical current, which increases in response to a decrease in the temperature of the permanent current switch.
The method for operating a superconducting magnet device according to claim 1 or 2, comprising the above. The operation of the superconducting magnet device according to any one of claims 1 to 3, which includes a step of stopping the supply of current by the main power source before the temperature of the permanent current switch reaches the steady operation temperature. Method. Claims 1 to 4 include a step of further lowering the temperature of the permanent current switch when the current flowing through the permanent current switch reaches the value at the time of steady operation to shift to steady operation. The method for operating the superconducting magnet device according to any one of the following items. The value of the current flowing to the permanent current switch and I _{t (t)} at time t,
Let T (t) be the temperature of the permanent current switch at time t.
The value of the critical current of the permanent current switch at the temperature T in the case of the I _{C (T),}
When lowering the temperature of the permanent current _switch, any of claims 1 to 5 and _{I t (t) <I C} (t), and that the time rate of change and _{(dI t / dI C) ≦} 1 The method of operating the superconducting magnet device according to item 1. Any of claims 1 to 6, wherein the period from the start of the increase to the completion of the increase of the current flowing through the permanent current switch is shorter than the period from the start of the temperature decrease of the permanent current switch to the completion of the decrease. The method of operating the superconducting magnet device according to item 1. The method for operating a superconducting magnet device according to any one of claims 1 to 7, wherein the rate of decrease in temperature of the permanent current switch is 1 K / min or less. With a superconducting coil,
With a permanent current switch,
A cooling unit that cools the superconducting coil and the permanent current switch and transfers them to superconductivity.
A heater that shifts the permanent current switch to a temperature higher than the critical temperature and transfers it to normal conduction while continuing cooling by the cooling unit.
The main power supply that supplies current to the superconducting coil,
A heater control unit that controls the heater and starts lowering the temperature of the permanent current switch toward a steady-state operating temperature lower than the critical temperature.
A main power supply control unit that starts to flow the current flowing through the superconducting coil to the permanent current switch by starting to reduce the current supplied from the main power supply.
A temperature control unit that lowers the temperature of the permanent current switch at a rate of decrease corresponding to the rate of increase in the current flowing through the permanent current switch.
A superconducting magnet device equipped with. A temperature sensor for detecting the temperature of the permanent current switch is provided.
Based on the temperature detected by the temperature sensor, the main power supply control unit controls the rate of increase in the current flowing through the permanent current switch, and the temperature control unit controls the rate of decrease in the temperature of the permanent current switch. Item 9. The superconducting magnet device according to Item 9. The permanent current switch forms a cylindrical shape in which a superconducting wire is wound without induction.
Superconducting magnet apparatus according to direction of the cylindrical axis to claim 9 or claim 1 0 wherein the permanent current switch in a state that is aligned with the direction of the magnetic force lines are arranged arising from the superconducting coil. The superconducting magnet device according to any one of claims 9 to 11, wherein the cooling unit is a conduction cooling type. The superconducting magnet device according to any one of claims 9 to 11, wherein the cooling unit is an impregnated cooling type.

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