CN1103925C - Superconducting magnet apparatus method of magnetizing same and magnetic resonance imaging system employing the same - Google Patents

Abstract

A superconducting magnet apparatus which includes a cryostat vessel for containing therein a coolant for realizing superconductivity, a magnetic flux generating unit disposed within the cryostat vessel and including a superconducting multilayer composite member constituting a sustaining medium for a persistent current which generates a magnetic flux along a center axis of a predetermined magnetic field space, and members holding the magnetic field generating unit within the cryostat vessel.

Description

Superconducting magnet apparatus, its Magnitizing method and use its magnetic resonance imaging system

The present invention relates generally to a kind of superconducting magnet apparatus.The invention particularly relates to and a kind ofly contain one therein and be used as superconducting magnet apparatus, a kind of method and a kind of magnetic resonance imaging system of using this superconducting magnet apparatus therein that magnetizes this superconducting magnet apparatus that static magnetic field produces the superconducting multilayer member in source.

As everyone knows, superconducting magnet apparatus has application in many different technology and industrial circle.In the former known common superconducting magnet apparatus, such as among the JP-A-4-49948 announcement crosses, superconductor is wound in the shape of similar coil and immerses and is contained in the low-temperature (low temperature) vessel and in the liquid helium as the cooling medium of realizing superconduction, thereby is used for producing in predetermined zone magnetic field.

Yet, thereby common superconducting magnet apparatus exists such problem promptly because to produce the decline of connection or contact resistance magnetic flux in the connecting portion branch of the superconductor that constitutes coil inevitable.In addition, the connection resistance of superconducting coil and mechanically deform are to produce the reason that superconductivity disappears.In addition, because manyly be contained in that superconducting coil twines and the interconnected processing of superconductor must be leaned on manual work, usually realizing experience difficulties aspect machining precision consistent.Certainly, high precision itself is difficult for reaching.In addition, do as a wholely, the size of superconducting magnet apparatus is big and heavy, has just produced another problem.

Prior art in view of above outline, the objective of the invention is to provides a kind of improved structure to superconducting magnet apparatus, can avoid the magnetic flux decline that produces effectively and guaranteeing can accomplish in its machining high-precision or accuracy and the high evenness that volume is little light with deal when preventing that producing superconductivity disappears.

Another object of the present invention is to provide a kind of above-described superconducting magnet apparatus is carried out magnetizing method.

A further object of the present invention provides a kind of magnetic resonance imaging system, has wherein used above-described superconducting magnet apparatus.

Because by describing, with the more obviously above and other purpose that becomes, provide a kind of superconducting magnet apparatus according to a total aspect of the present invention, it comprises that one is used for holding therein the low-temperature (low temperature) vessel of the cooling medium that is used to obtain superconductivity, one is contained in this low-temperature (low temperature) vessel and comprises that one is configured for a superconducting multilayer member of keeping the medium of persistent current, this electric current produces along the magnetic flux of the axis of determined magnetic place, and is used for magnetic field generation device is fixed on member in the low-temperature (low temperature) vessel.

In having the structure of above-mentioned superconducting magnet apparatus, static magnetic field produces the source by being used as maintenance or keeping the superconducting multilayer member formation that flows through the medium of persistent current around predetermined axial line (producing magnetic flux along this axis).In fact the static magnetic field source that produces that is made of the superconducting multilayer member does not need to be electrically connected.In addition, in fact can not exist as under the situation of common coil, run into easily take place that machinery changes or plastidule 13 is produced in the magnetic field of deformation.Correspondingly, the magnetostatic field source that is made of the superconducting multilayer member can be avoided fully as resulting from the decline of magnetic flux of the connection resistance that the place of being electrically connected produces, and the phenomenon or the thing that take place do not wished in the superconductivity disappearance that heating caused that causes owing to mechanical deformation or other reason etc.In addition, because the static magnetic field that is made of the superconducting multilayer member source that produces can make in a large number and not need to make winding step required in the common superconducting coil and be electrically connected step, thereby can guarantee high precision or accuracy and uniformity coefficient and high-quality.In addition, because the magnetic field generation source structure of being made by the superconducting multilayer member is simple,, makes as a whole superconducting magnet apparatus and can do to such an extent that size is little and in light weight when comparing with common coil form static magnetic field generation source.

By reading the description of the most preferred embodiment of the present invention that next adopts with reference to the accompanying drawings, only by way of example, can more easily understand above-mentioned purpose of the present invention and other purpose, characteristics and bonus.

In the description afterwards, will be with reference to the accompanying drawings, wherein:

Figure 1A illustrates according to one embodiment of the present of invention to comprise that the cylindrical shape static magnetic field of being made by the superconducting multilayer member produces the structural drawing of the superconducting magnet apparatus in source;

Figure 1B is the sectional view that obtains along the IB-IB line shown in Figure 1A;

Fig. 2 A shows according to an alternative embodiment of the invention and comprises the superconducting magnet apparatus that produces plane (discoid) the superconducting multilayer member in source as magnetostatic flux density;

Fig. 2 B shows the sectional view that obtains along Fig. 2 A center line IIB-IIB;

Fig. 3 is the synoptic diagram that is provided to show by the exemplary device of using the cylindric superconducting multilayer member shown in electric heater heating Figure 1A;

Fig. 4 illustrates the schematic representation of apparatus that is used to heat discoid superconducting multilayer member shown in Fig. 2 A;

Fig. 5 is the figure that the following several methods of magnetization superconducting multilayer member is shown with curve map;

Fig. 6 A is the figure that foundation first kind of Magnitizing method of the present invention is shown with curve map to 6E;

Fig. 7 A is the figure that foundation second kind of Magnitizing method of the present invention is shown with curve map to 7E;

Fig. 8 A is the figure that foundation the third Magnitizing method of the present invention is shown with curve map to 8F;

Fig. 9 illustrates the structural drawing that is provided with the superconducting magnet apparatus of a magnetic shielding according to another embodiment of the present invention;

Figure 10 is the sectional view of the superconducting magnet apparatus that obtains along X-X line among Fig. 9;

Figure 11 is provided to show the figure that is used to magnetize the Magnitizing method of superconducting magnet apparatus according to an alternative embodiment of the invention according to active method for shielding;

Figure 12 is the structural drawing that illustrates according to the superconducting magnet apparatus of the generation vertical magnetic field form of another embodiment of the present invention;

Figure 13 is the synoptic diagram that illustrates according to the another kind of structure of the superconducting magnet apparatus of another embodiment of the present invention;

Figure 14 is the structural representation that illustrates according to the superconducting magnet apparatus of the vertical magnetic flux density form of the generation that is provided with magnetic shielding of another embodiment of the present invention;

Figure 15 is illustrated in to be used as static magnetic field in the device shown in Figure 14 and to produce graph of a relation between the superconducting multilayer member in source and the magnetic shielding;

Figure 16 illustrates the sectional view that is placed on the superconducting magnet apparatus of the magnetizing coil in the low-temperature (low temperature) vessel according to comprising of another embodiment of the present invention;

Figure 17 is the sectional view that passes through cylindric superconducting multilayer member is curved substantially the superconducting magnet apparatus of C shape formation that illustrates according to another embodiment of the present invention;

Figure 18 is the sectional view that the XVIII-XVIII line along Figure 17 obtains;

Figure 19 is the structural drawing that illustrates according to the pad that is used for realizing that the uniform magnetic flux amount distributes of one embodiment of the invention;

Figure 20 is the structural drawing that illustrates according to the cylindric superconducting multilayer member of one embodiment of the invention;

Figure 21 is the synoptic diagram that illustrates according to another structure of the cylindric superconducting multilayer member of another embodiment of the present invention;

Figure 22 is the synoptic diagram that illustrates according to another structure of the cylindric superconducting multilayer member of another embodiment of the present invention;

Figure 23 is the synoptic diagram that illustrates according to another structure of the cylindric superconducting multilayer member of another embodiment of the present invention;

Figure 24 is that the cylindric superconducting multilayer member of spot heating that passes through that illustrates according to another embodiment of the present invention makes the uniform schematic representation of apparatus of magnetic flux distributions;

Figure 25 A and 25B illustrate with curve map to constitute the principle of installing shown in Figure 24;

Figure 26 illustrates the figure that the static magnetic field that is made of the superconducting multilayer member according to comprising of another embodiment of the present invention produces the superconducting magnet apparatus of source and pad;

Figure 27 is the sectional view that obtains along XXVII-XXVII line among Figure 26;

Figure 28 is the figure that illustrates according to the pad of another embodiment of the present invention;

Figure 29 illustrates the sectional view of another embodiment that the static magnetic field that is made of the superconducting multilayer member according to comprising of another embodiment of the present invention produces the superconducting magnet apparatus in source;

Figure 30 illustrates to comprise that according to one embodiment of the invention one produces source and as static magnetic field and has the high space of opening wide property and be used to hold a figure who checks with the superconducting magnet apparatus of the superconducting multilayer member of object;

Figure 31 is similar to the figure of Figure 30 and shows to be provided with a mirror and to hold a superconducting magnet apparatus of unlimited property of checking the object space of usefulness with increase; And

Figure 32 generally illustrates with the block scheme of superconducting multilayer member as the hardware configuration of the magnetic resonance imaging system in static magnetic field generation source.

Now, be considered to best or typical embodiment with reference to the accompanying drawings according to the present invention at present and describe the present invention, in the following description, same-sign represents to have the identical or appropriate section of effect of equal value in some figure.In the description equally afterwards, be interpreted as the speech of convenient and usefulness and should be used as the speech that limits usefulness to them such as speech such as " left side ", " right side ", " top ", " bottom ", " vertically ", " levels ".

Figure 1A and Figure 1B illustrate the superconducting magnet apparatus that is applicable to magnetic resonance imaging system according to one embodiment of the invention, and wherein Figure 1A is its vertical cross section and Figure 1B illustrates in general the section that gets along IB-IB line among Figure 1A.For the present superconducting magnet apparatus of considering, the superconducting multilayer member of cylinder-like structure produces the source as static magnetic field.In the drawings, label 11 representatives have the low-temperature (low temperature) vessel of the cylindric hollow cavity (also being called coolant cavity) of isolating with extraneous heat, wherein, in common superconducting coil system, generally be contained in the hollow cavity with the cooling medium inlet 12 that is contained in low-temperature (low temperature) vessel 11 tops as the liquid helium of cooling medium for the realization superconductivity.Be immersed in the cooling medium that is contained in low-temperature (low temperature) vessel is the cylinder-like part 13 that is made of the superconducting multilayer member (also being called cylindric superconducting multilayer member later on) that produces the source as static magnetic field.Thereby cylinder-like part 13 is supported and can stably be fixed on low-temperature (low temperature) vessel preposition place to cylindric superconducting multilayer member 13 by supporting member 14a that is arranged in its two ends and 14b.Supporting member 14a and 14b are fixedly secured in low-temperature (low temperature) vessel 11.During this time, though in diagram, omitted through hole, cooling medium can freely be flowed in cylinder-like part 13 thereby should mention the through hole that has a suitable number at supporting member 14a and 14b.These through holes will be called the coolant flow hole later.In addition, so form through hole 33, make it pass low-temperature (low temperature) vessel 11, prolong along the axis.Be used for as foundation the present invention under the situation of this embodiment of magnetic resonance imaging system, this through hole 33 is used as to hold and is used to check or the space of the object of purpose such as diagnosis.

Say that by the way each supporting member 14a and 14b have haply and equate or matched coefficient of thermal expansion with magnetostatic flux generation source.

As a preferable superconducting multilayer member, can mention a kind of niobium titanium/niobium/copper (NbTi/Nb/Cu) superconducting multilayer member of 1 millimeters thick, it can be by piling up or stacking NbTi layer (for example 30 layers) and Cu layer (for example 31 layers) alternately with each other, and every Nb layer be inserted in NbTi between layer and Cu layer (for example altogether 60 layers) thus two surfaces of making Mnltilayered structures all are made of the Cu layer respectively, make Mnltilayered structures through roll extrusion or the cold rolling of being heated thereafter again.By the way say, can use the combination thin layer member of making by many thin layers of integrally piling up every agreement that contracts a film or TV play to an actor or actress 1 millimeters thick that obtains by roll extrusion equally.NbTi/Nb/Cu superconducting multilayer member or the combination sheet members so made by deep-draw form a cup, cut the bottom of cup then, thereby form the cylinder-like part 13 of superconducting multilayer member.To the above-mentioned more detailed data of making the method for NbTi/Nb/Cu superconducting multilayer member, can be with reference to " electronics and The Institution of Electrical Engineers use the superconductivity transactions ", the 3rd volume, the 1st phase (in March, 1993), 177-180 page or leaf.

In cylindric superconducting multilayer member 13, a steady current flows along circumferential direction.So, because this steady current produces or has formed static magnetic field in the inner space that the through hole 33 by cylinder-like part 13 is limited.

Understand easily, cylindric superconducting multilayer member 13 must not be electrically connected or contact haply.In addition, in fact cylinder-like part 13 can not bear mechanical deformation in common superconducting coil type magnet apparatus situation.Thereby, cylindric superconducting multilayer member can prevent from fully to result from the place of being electrically connected connection resistance magnetic flux decline and result from generation heat that mechanical deformation and other reason cause and the superconductivity that causes disappears.In addition, because cylindric superconduction member 13 can need not to make the electric wire winding step of common superconducting coil type magnet apparatus and be electrically connected step by deep-draw and cutting process, guarantee high precision, high evenness and high-quality to cylinder-like part 13 thereby to superconducting magnet apparatus.In addition, because the static magnetic field of realizing with cylindric superconducting multilayer member produces the simple in structure of source, when comparing with common superconducting coil type static magnetic field generation source, it is little and in light weight that superconducting magnet apparatus is made the as a whole size that can realize, this is again its a big advantage.

Fig. 2 A and 2B show the superconducting magnet apparatus according to another embodiment of the present invention, and wherein Fig. 2 A is its vertical cross section and Fig. 2 B shows the section that obtains along the IIB-IIB line of Fig. 2 A.Following description will also be designed at the superconducting magnet apparatus according to this embodiment carrying out under the supposition of magnet apparatus of magnetic resonance imaging system.With reference to these figure, low-temperature (low temperature) vessel 11 has with extraneous thermal isolation and is adapted at wherein holding is the required cylindric hollow cavity that is used as the cooling medium liquid helium of realization superconductivity, and wherein cooling medium inlet 12 is contained in the top of low-temperature (low temperature) vessel.Immerse many disk 43a that constitute by the superconducting multilayer member in the cooling medium that is included in the low-temperature (low temperature) vessel 11 to 43f, these disks are placed side by side each other and are constituted static magnetic field and produce the source, wherein respectively at disk 43a to the zone line formation magnetic line of force tunnel holes 44a of 43f to 44f.Each all is fixedly secured on the supporting member 45 that is installed on low-temperature (low temperature) vessel 11 inwalls to 43f by the disk 43a that superconduction (also being called discoid superconducting multilayer member later on) constitutes.By the way, should note through hole 33 also as the situation of the superconducting magnet apparatus as shown in Figure 1A, the direction along the axis 39 of low-temperature (low temperature) vessel 11 in low-temperature (low temperature) vessel 11 is extended.

As a preferable superconducting multilayer member, the NbTi/Nb/Cu superconducting multilayer member that a kind of 1 millimeters thick is arranged that can mention, it can be by piling up NbTi layer (for example 30 layers) and Cu layer (for example 31 layers) alternately with each other, and the insertion Nb layer between NbTi layer and Cu layer (for example altogether 60) thereby and two surfaces of making the Mnltilayered structures of finishing all are made of the Cu layer respectively, make Mnltilayered structures through roll extrusion or the cold rolling of being heated thereafter again.From the NbTi/Nb/Cu superconducting multilayer of such acquisition combination thin slice,, can produce and have the shape and size that design and the discoid superconducting multilayer member of magnetic line of force tunnel holes by operation or the operation that is fit to.

In 43f, persistent current flows around each magnetic line of force opening 44a to 44f at every discoid superconducting multilayer member 43a.Thereby, magnetic flux thereby pass magnetic line of force opening 44a and produce or form by persistent current to the magnetic field of 44f.

According in the superconducting magnet apparatus of present embodiment of the present invention, the disk 43a that is made of the superconducting multilayer member is to the number of the 43f number of turn corresponding to superconducting coil.Therefore, by increasing the quantity of disk, the magnetic field intensity of generation can correspondingly increase.Clearly, have the superconducting magnet apparatus according to present embodiment of this structure, can obtain to be similar to the favourable effect of first embodiment.

Also should mention, have the tabular of different geometries or flat superconducting Mnltilayered structures can be used for replacing make annular disk 43a to 43f.

The method of the cylindric superconducting multilayer member 13 of magnetization will be described with reference to Figure 1A in addition.

Concerning magnetization, the magnetizing coil 16 that is connected to field power supply 15 inserts in the through hole 33.With reference to Figure 1A.Concerning magnetizing cylindric superconducting multilayer member, can expect the following three kinds of methods (1) that will describe, (2) and (3).Magnitizing method (1)

According to this Magnitizing method (1), cylindric superconducting multilayer member 13 is adjusted to superconducting state from normal conducting state, and therefore the intensity that is used for magnetized external magnetic field that is applied is reduced to zero gradually under superconducting state.

Fig. 5 shows the external magnetic field Ha that applies from outside one side of superconducting multilayer member and relation between the magnetic flux density B of the outside relative side of superconducting multilayer member.With reference to this figure, the straight line of y=ax representative is the relation between external magnetic field Ha and the magnetic flux density B under normal conducting state.In addition, symbol H ' _C1Representative is passed the superconducting multilayer member and is appeared at intensity corresponding to the external magnetic field of the opposite side of applying side, and H _C2Represent upper critical strong.According to the Magnitizing method of considering now 1., 1. apply the such process in external magnetic field by path as shown in Figure 5, edge, the result is used to keep magnetic flux B ₁Persistent current flow through cylindric superconducting multilayer member 13.

Now, to 6E, will be described more specifically Magnitizing method (1) with reference to Figure 1A and Fig. 6 A.

At first, low-temperature (low temperature) vessel 11 state that is evacuated.In other words, cylindric superconducting multilayer member 13 is in the temperature that is higher than superconducting state at first.In this state, magnetizing coil 16 is supplied with exciting current from field power supply 15 (with reference to figure 6C).Magnetizing coil 16 can be a solenoid type.When exciting current is flowed through magnetizing coil 16, thereby the magnetic flux that has produced the annular distribution of passing magnetizing coil 16 hollow spaces is formed for magnetized external magnetic field (6D with the aid of pictures).Ring-type magnetic flux has annular section that runs through cylindric superconducting multilayer member 13 1 walls and the annular section that does not run through cylindrical structural member 13 round cylindric Mnltilayered structures 13 to the outside expansion.In a word, ring-type magnetic flux causes along flow through cylindric superconducting multilayer member 13 and be used for capturing the induced current that runs through magnetic flux wherein of its circumferencial direction.Yet because temperature is than realizing the required temperature height of superconducting state, induced current is reduced to zero (6B with the aid of pictures) very soon owing to the resistance of cylindric superconducting multilayer member 13.

Then, low-temperature (low temperature) vessel 11 is at the moment t shown in Fig. 6 A ₁Charge into as the cooling medium liquid helium of realizing superconducting state.So cylindrical shape superconducting multilayer member 13 is cooled to such temperature, the cylindric superconducting multilayer member 13 under this temperature can suppose to be in superconducting state.After this, the curve a shown in Fig. 6 C shows that the exciting current of supplying with magnetizing coil 16 from field power supply 15 is decreased to the limit zero gradually.So, fix or keep the superconductivity curve of the cylindric Mnltilayered structures 13 of a steady current according to its electric current, along being used for keeping the direction of a constant magnetic flux to produce supercurrent (6B with the aid of pictures) at cylindric superconducting multilayer member 13, therefore, ring-type magnetic flux produces (with reference to figure 6E) by supercurrent.As the results of static magnetic field 39 continuous generations along the axis, this flux loop has expanded space 33 along the axis 39 of cylindric Mnltilayered structures 13.In case after cylindric superconducting multilayer member 13 was magnetized to and is used to keep or fixes the medium of a steady current, magnetizing coil 16 had just been removed from space 33, this space can be used to settle the inspection object of waiting to obtain magnetic resonance image (MRI) now.Magnitizing method (2)

The method is by 2. implementing along path shown in Figure 5.That is, the intensity increase that is adjusted to superconducting state and external magnetic field of cylindric Mnltilayered structures 13 will be fixed on the value predetermined among the area I I.Behind one section preset time, the external magnetic field drops to zero gradually.Below with reference to Figure 1A and Fig. 7 A to 7E this Magnitizing method is elaborated.

Shown in Fig. 7 A and 7C, when cylindric superconducting multilayer member 13 is in the temperature that is assumed to superconducting state the exciting current in the magnetizing coil 16 of flowing through is increased when keeping gradually, produce and the 33 magnetic flux increases of expanding by magnetizing coil 16 through the space, thereby be formed for magnetized external magnetic field, the result is along bearing the electric current (with reference to figure 7B) that flows circlewise through cylindric superconducting multilayer member 13 corresponding to the sense of direction that stops current increases in the superconductivity curve of cylindric superconducting multilayer member 13.When reaching external magnetic field strength, the electric current of the magnetizing coil 16 of flowing through exceeds intensity H ' _C1Predetermined value the time, electric current remains on its size in a predetermined time interval.That is, when pass space 33 carry out magnetized magnetic flux and thereby the electric current that in cylindric superconducting multilayer member 13, along the circumferential direction generates when all having reached separately predetermined value, they remain on respectively on this value.Then, shown in Fig. 7 C, when the electric current of the magnetizing coil 16 of flowing through is decreased to zero gradually, in cylindric superconducting multilayer member 13, along the circumferential direction induce electric current with the reverse direction current flow of when magnetic flux increases, inducting according to its superconductivity characteristic, thus, shown in the curve a among Fig. 7 B, even the induced current that along the circumferential direction flows when the electric current vanishing of the magnetizing coil of flowing through is fixed as the steady current that is in a certain value as mentioned above, like this, the magnetization degree shown in Fig. 7 E can be realized by steady current.Magnitizing method (3)

3. this Magnitizing method by realizing along path shown in Fig. 5 or circuit.In the I district, heat cylindric superconducting multilayer member 13 and make it temporarily to a normal condition.And then cylindric superconducting multilayer member 13 is adjusted to superconducting state and external electrical field intensity reduces gradually.

This Magnitizing method will be with reference to Figure 1A and Fig. 8 A to 8F in the following more specific description of carrying out.By keeping cylindric superconducting multilayer member 13 in superconducting state, thereby the exciting current that is added to magnetizing coil 16 increases the intensity adjustments of external magnetic field gradually to less than magnetic field intensity H ' _C1A predetermined value.Then, under this state, be contained in inner well heater to cylindric superconducting multilayer member 13 heating by use, thereby regulate this cylindric superconducting multilayer member 13 to normal condition (seeing Fig. 8 A and 8F).Like this, set up such state, wherein the external magnetic field can freely be passed in the inside of cylindric superconducting multilayer member 13.Then, thus turning off above mentioned well heater makes cylindric superconducting multilayer member 13 return to superconducting state.Under this state, thereby exciting current reduces that the intensity of external magnetic field is descended gradually (seeing Fig. 8 C and 8D).In this process, produced the induced current (seeing Fig. 8 B) of the magnetic flux that can keep passing cylindric superconducting multilayer member 13 inside effectively.This induced current has become steady current, can realize the magnetization degree shown in Fig. 8 E thus.

Fig. 3 and 4 illustrates the installation of above mentioned well heater by way of example.Particularly, the device that wherein contains cylindric superconducting multilayer member 13 shown in Figure 1A has been shown among Fig. 3 to be heated by a well heater 46, well heater is so installed, thereby a part of wall of cylindric superconducting multilayer member 13 is surrounded by the well heater 46 that links to each other with the power supply 47 that is provided by the outside by switch SW.

On the other hand, for the device shown in Fig. 4, well heater 46 as above is installed is made it to fold to 43f with each the disk 43a shown in Fig. 2 A.The device of other structures is identical with shown in Fig. 3 basically.

Fig. 9 and 11 illustrates the superconducting magnet apparatus that is provided with magnetic shielding according to an alternative embodiment of the invention, and wherein Figure 10 is the sectional view that obtains along X-X line among Fig. 9.

With reference to these figure, label 11 represents one with extraneous thermal isolation and be divided into the low-temperature (low temperature) vessel of two coolant room 23 and 24 by dividing plate 22.In coolant room 23 and 24, all contain as the cooling medium liquid helium of realizing superconductivity.In addition, provide respectively to accompany, be used for to the cooling medium inlet 25 and 26 that wherein injects cooling medium with coolant room 23 and 24.Be contained in the coolant room 23 is to be used for or to constitute the cylindric superconducting multilayer member 13 that static magnetic field produces the source.Cylindric superconducting multilayer member 13 supports by the supporting member 14 that is fixedly secured in the low-temperature (low temperature) vessel 11, thereby supporting member 14 has a considerable amount of coolant flow hole 29 liquid helium is circulated therein.Thereby be contained in the coolant room 24 is by the round box-like member 30 that is made of the superconducting multilayer member that covers cylindric superconducting multilayer member 13 as magnetic shielding.Cooling medium can flow in this circle box-like member 30 in low-temperature (low temperature) vessel 11 thereby circle box-like member 30 is fixedly secured.

Be contained in that to produce as static magnetic field in cylindrical shape superconducting multilayer member 13 inner spaces 33 in source be to be connected to the tubular magnetizing coil 16 of helical that field power supply 15 goes.Magnetic flux block piece (flux impeding member) constitutes (seeing the left end of figure) on an end of the axis 39 in space 33.The magnetic flux block piece constitutes by being filled with as the container 41 of the cooling medium liquid helium of realizing superconductivity and the superconducting multilayer member 42 that immerses wherein.To superconducting multilayer member 42, can use the NbTi/Nb/Cu superconducting multilayer member in aforesaid cylindric superconducting multilayer member 13 and the circle box-like member 30.

It is taken away after cylindric superconducting multilayer member 13 magnetic historys are brought into use magnetic flux block piece 40 and finished magnetization from initial.

On the other hand, cooling medium inlet 25 and 26 is connected on the coolant supply 38 by valve 36 and 37 respectively.Lid by taking away cooling medium inlet 25 and 26 is also opened valve 36 and 37, just the cooling medium liquid helium as superconductivity is injected into respectively in coolant room 23 and 24.

In magnetization, at first, will be full of liquid helium in the coolant room 24 and coolant room 23 to keep be empty, thereby make round box-like member 30 remain on superconducting state.According to Magnitizing method (1), a kind of method in (2) and (3) is magnetized cylindric superconducting multilayer member 13 then.

Because maintain and be used to set up under the temperature of superconducting state in circle box-like member 30, the effect of circle box-like member 30 is magnetic shieldings, and is that produce and tend to outside leaked magnetic flux amount or magnetic field and will justify box-like member 30 thus and shield by cylindric superconducting multilayer member 13.In addition, produce by magnetizing coil 16 and be forced to turn back to magnetic shielding 30 and not to external leakage along the magnetic flux that axis 39 extends to the end (seeing the left end among the figure) in space 33.This is because magnetic flux block piece 40 is made of container 41 that is full of liquid helium and the superconducting multilayer member 42 that is contained in the container 41, and because the effect of this superconducting multilayer member 42 is as magnetic shielding.Rely on this device, can improve the magnetic flux that produces by magnetizing coil 16 magnetization efficient greatly cylindric superconducting multilayer member 13.

Figure 11 illustrates another embodiment that is used for illustrating according to the superconducting multilayer member magnetizing assembly of the Magnitizing method of principle of the present invention.Device shown in this figure and the difference of installing shown in Fig. 9 be magnetic flux block piece 40 be by the coil 43 that is connected to field power supply 15 constitute this coil be used for producing with by or extend the opposite magnetic flux of direction of the magnetic flux in space 33.When 15 pairs of coils 43 of field power supply provide electric current, coil 43 produces the opposite magnetic flux of annular magnetic flux directions that produces with magnetizing coil 16, and wherein the magnetic flux effect that is produced by coil 43 is tending to along axis 39 to the magnetic flux of an end (seeing left end among the figure) extension in space 33 to reverse repulsion.Thereby,, can improve the magnetization efficient of cylindric superconducting multilayer member 13 greatly with the device shown in Figure 11.

Figure 12,13,14 and 15 illustrates the other embodiment of superconducting magnet apparatus, and wherein each has all adopted the superconducting multilayer member that produces the vertical direction static magnetic field.

In Figure 12, label 11 representative is with extraneous thermal isolation and wherein be full of the low-temperature (low temperature) vessel of the cooling medium liquid helium that is used to realize superconductivity.Low-temperature (low temperature) vessel 11 is made somewhat square C shape structure, and wherein the container part of upper and lower describes that by being contained in drawing bridge behind device partly connects, as shown in figure 12.In the inner plane of low-temperature (low temperature) vessel 11, static magnetic field is housed produces source 27a and 27b and static magnetic field generation source 28a and 28b, wherein each all makes disc superconducting multilayer member, as shown in figure 13.Produce source 27a and 27b installs in opposite directions with the static magnetic field generation source 28a and the 28b that are supported by the supporting member 14d in the other end by the static magnetic field that supports at one supporting member 14c, and be inserted with space outerpace 33 therein.Label 22a and 22b are illustrated in the magnetizing coil of removing after the magnetization of above-mentioned static magnetic field generation source.Static magnetic field produces source 27a, 27b and 28a, the persistent current I among the 28b by flowing through respectively ₁And I ₂Center pit, static magnetic field that the magnetic flux B that produces has formed through the space 33, static magnetic field produces source 27a and 28a produce source 27b and the center pit of 28b and the flux path (with reference to Figure 13) in space 33.That is, in space 33, formed the static magnetic field (seeing Figure 12) of vertical direction.Say that by the way space 33 is as holding the object of checking usefulness, the magnetic resonance imaging system of the superconducting magnet apparatus that its image will be considered by being equipped with is searched.

Though two pairs of disks that each all is made of the superconducting multilayer member or flat disc (pancake) all are used in the device that has illustrated and have suffered, the present invention does not limit the concrete quantity of disk.Some structures that can expect are two or multi-disc disk or flat disc that formed by the superconducting multilayer member by certain preset space length ground homeotropic alignment in this device.

Next will turn to description to Magnitizing method.

Thereby magnetizing coil 22a and 22b link to each other with field power supply 15 and make them have separately polarity on same direction.Produce magnetic field as shown in figure 12 thus.

On the other hand, cooling medium injects low-temperature (low temperature) vessel 11 from cooling medium supply source 38 through the cooling medium inlet of valve 36 and low-temperature (low temperature) vessel 11.

Can be according to given a kind of magnetization the in aforementioned three kinds of Magnitizing methods (1), (2) and (3).

Being shown in the superconducting magnet apparatus of Figure 14 and 15 and the difference of the device in above-mentioned Figure 12 and 13 is to replace static magnetic field to produce source 28a and 28b with active magnetic shielding 29a and 29b.Though on each static magnetic field generation source 28a and 28b, be formed with sizable opening or perforate, on active magnetic shielding 29a and 29b, but do not have opening.

Consider that from the angle of magnetic shielding as shown in figure 15, the diameter of active magnetic shielding 29a and 29b preferably should be chosen as the diameter that produces source 27a and 27b greater than static magnetic field.

Describe now and have the Magnitizing method of the superconducting magnet apparatus of structure as shown in figure 14.

In Figure 14, label 22a represents to make static magnetic field to produce source 27a and the magnetized magnetizing coil of 27b.Magnetizing coil 22a links to each other with field power supply 15a.And two magnetizing coil 22b are connected with field power supply 15b.But the polarity of magnetizing coil 22b is opposite with magnetizing coil 22a's.Produce the magnetic field 102,103 and 104 of direction as shown in figure 14, edge thus.

Under above-mentioned configuration, realize magnetization by such adjusting, make and in magnetic shielding 29a and the effective armoured magnetic field of 29b, can realize predetermined magnetic field intensity by field power supply 15a and 15b.

Magnitizing method is selected in three kinds of Magnitizing methods (1), (2) and (3) from above.

In the described embodiment situation of Figure 12-15, adopt the disk of making by superconducting multilayer combination thin slice to make static magnetic field and produce the source.But should be noted that and equally also can adopt cylindric superconducting multilayer member, and have same favourable effect.

Figure 16 represents the superconducting magnet apparatus that includes magnetizing coil according to another embodiment of the present invention.Among the figure, parts identical with aforementioned functional or that be equal to are represented with identical label.

As seen from Figure 16, the cylindric static magnetic field generation source 13 of superconducting multilayer member formation is placed and is embedded in the cylinder 31 that is fastened in the low-temperature (low temperature) vessel 11 around the axis 39 that is formed at the central through hole 33 in the low-temperature (low temperature) vessel 11 in low-temperature (low temperature) vessel 11.The spiral cast field coil 34 that the cylindric static magnetic field of being made by the superconducting multilayer member as magnetization produces source 13 is positioned at low-temperature (low temperature) vessel 11 and is supported by cylinder 31.Therefore, realized producing source 13 and field coil 34 with substantial one-piece construction by the cylindric static magnetic field that the superconducting multilayer member is made.Additional disclosure be that cylinder 31 can be made of glass fiber reinforced plastics (fiber reinforcedplastic FRP) material.

The relative side of the axle in source 13 produces source 13 with cylindric static magnetic field and field coil 34 covers from producing with static magnetic field thereby also be the inwall of being close to low-temperature (low temperature) vessel 11 by the magnetic shielding 30 that superconducting multilayer combination thin slice is made.

The power supply connector part 90 that the top of low-temperature (low temperature) vessel 11 is equipped with cooling medium inlet 25 and is used for powering to field coil 34.

Magnetic shielding 30 also can once in a while.And this class formation can adopt in the structure that low-temperature (low temperature) vessel is divided into two equally, wherein only cooling magnetic shielding separately.In this case, the structure of superconducting magnet apparatus and device shown in Figure 9 is similar.

Comprising that shown in Figure 12 and 14 in the structure of field coil, field coil can be positioned at the outside of superconducting multilayer member 27a and 27b.

Magnitizing method can be any one in aforementioned three kinds of methods (1), (2) and (3).

Figure 17 represents the superconducting magnet apparatus according to another embodiment of the present invention, and it curves C shape by the large diameter pipe with the superconducting multilayer member and is shaped.Among the figure, the parts of same as described above or equivalent function are with identical character representation.

As seen from the figure, the low-temperature (low temperature) vessel isolated with external heat has the C tee section, and wherein low-temperature (low temperature) vessel 11 is divided by the dividing plate 22 of closed at both ends or is divided into two coolant room 23 and 24.Relevant with coolant room 23 and the 24 cooling medium inlet 25 and 26 of respectively liquid helium being introduced coolant room 23 and 24 that provided.Be positioned in the coolant room 23 is that the tubulose static magnetic field that adopts the superconducting multilayer unitized construction and have a C font vertical cross-section produces source 27.Put relatively at the two ends in tubulose static magnetic field generation source 27, is separated with unlimited space outerpace 33 therebetween mutually.And the outside surface in tubulose static magnetic field generation source 27 or the inside of tubular part 27 are wound with one or more field coils 32 of line solenoid loop-shaped.Label 50 expressions are used for the power supply terminal of field coil 32.Thereby make and magnetic shielding 51 with C shape vertical cross-section is positioned at coolant room 24 outside surface that the tubulose static magnetic field produces source 27 is surrounded by the superconducting multilayer member.And in coolant room 24, the tubulose static magnetic field is placed the discoid pad of being made by the superconducting multilayer member 52 respectively near producing 27 two ends, source, and wherein the discoid pad 52 of each piece all comprises a magnetic flux tunnel holes at least, as shown in figure 19.As magnetic lines of flux 53 indications, the tubulose static magnetic field produces the magnetic flux extension of source 27 generations and passes through space 33, form static magnetic field thus in space 33, space 33 is used for placing the object of examine or diagnosis, and its image is extracted by the magnetic resonance imaging system that comprises superconducting magnet apparatus.Particularly, the object of examine or diagnosis is put in can be from right to left or along on the worktable that moves perpendicular to the accompanying drawing page, thus the object of examine placed in the space 33.

The superconducting multilayer member that should further be pointed out that the embodiment that is used for Figure 17 also can be realized with same as shown in Figure 1 or similar cylinder 13.

The sectional view of Figure 18 for getting along Figure 17 center line XVIII-XVIII.

Discoid pad 52 shown in Figure 19 below will be described.

Usually, in the tubulose static magnetic field produces source 27, the inner track that most of magnetic flux will be by tubulose static magnetic field generation source but not external path.Therefore, magnetic flux distributions is always uneven in space 33.Thereby provide discoid pad 52 to be used for proofreading and correct uneven magnetic flux and obtain uniform magnetic flux distributions.For this reason, partly have the hole of negligible amounts or minor diameter and partly to have quantity in periphery more or reach the hole of diameter in the inside circumference of pad 52.Certainly, the shape of through hole is not limited to circle.

Use field coil 32 to magnetize to adopt a kind of in above-mentioned three kinds of given Magnitizing methods (1), (2) and (3).

Next, will describe the static magnetic field that adopts the superconducting multilayer unitized construction by Figure 20 and produce the structure in source 13.

The static magnetic field of being made by the superconducting multilayer member produces the roughly uniform cylinder part of main body employing thickness in source 13.As Figure 20 finding, the inside diameter D 2 of cylinder part end is less than the inside diameter D 1 at its central authorities or middle part.And, adopt for the geometry of the longitudinal axis or central shaft 39 symmetries and produce uniform static magnetic field thereby produce source 13 along the vertical central axis 39 in cylindric space by the cylindric static magnetic field that the superconducting multilayer member is made.In addition, in superconducting magnet apparatus shown in Figure 20, cylindric superconducting multilayer combiner 13 is made its diameter and is progressively reduced along the direction from central authorities to two ends.The shape of cylindric Mnltilayered structures 13 transition portions also can be the part of circumference.

Figure 21 represents to produce according to static magnetic field of the present invention another embodiment in source 13.In this embodiment of the present invention, the static magnetic field generation source 13 of being made by the superconducting multilayer assembly comprises three zones, promptly have predetermined constant diameter zone line A and with continuous two end regions B and the C of zone line A, wherein to make axial cross section be truncated cone shape for end regions B and C.Under the configuration of as shown in figure 21 superconducting magnet apparatus, can obtain the beneficial effect identical with Figure 20, can also further improve the static magnetic field whole homogeneity that distributes thus.

Figure 22 represents to produce according to the static magnetic field of another embodiment of the present invention the structure in source 13.In the static magnetic field generation source according to this embodiment of the present invention, the static magnetic field generation source 13 of being made by cylindric Mnltilayered structures is made of the cylinder part 60,61 and 62 that a plurality of diameters reduce successively.In an illustrated embodiment, the number of supposing cylinder is 5.In this case, as shown in figure 22, each cylinder does not need direct interconnection, is exactly so that the axial magnetic field that each cylinder produces is interference-free basically as long as arrange regularly.Though supposition here adopts 5 cylinders to constitute the superconducting multilayer combinatorial cylinders,, self-evident, adopt at least 3 right cylinders just can reach purpose of the present invention.In this case, must increase the length of cylinder 60 as requested like that.And, obviously, can obtain basically and same useful effect shown in Figure 20 by the number that increases cylinder or parts.

Owing to only use some cylinder parts just can constitute superconducting magnet apparatus respectively, so can reach useful effect in difficult avoiding making according to this embodiment of the present invention with predetermined diameter.

It should be understood that said structure just is used for explaining principle of the present invention.Because those skilled in the art are easy under the situation that does not deviate from the spirit and scope of the invention it be made a large amount of improvement or combination, so accurate structure and operation that the present invention is not limited to state.For example, be truncated cone in superconducting magnet apparatus medial end portions zone shown in Figure 21, but should be appreciated that the outside surface of cone is not necessarily linear, can be shaped form also, thereby its diameter is reduced gradually towards end regions.

By the diameter at cylindric superconducting multilayer member two ends being done less than the diameter in the middle part of it, the position that can make magnetic flux bleed-through is away from central authorities or middle part, thus can be more even along the magnetic flux distributions than cylinder on the whole superconducting magnet apparatus length direction with same diameter, this also means the size that can further dwindle superconducting magnet apparatus.

Next, by Figure 23 will describe according to the present invention again one the step embodiment the static magnetic field of employing superconducting multilayer member produce the source.

Producing source 13 according to the static magnetic field of being made by the superconducting multilayer member of present embodiment, to comprise predetermined diameter be D1 and the wall thickness roughly uniform first cylindric superconducting multilayer compound tube 54, the second cylindric superconducting multilayer compound tube 55 with the diameter D3 that is slightly larger than first cylindrical pipe 54 and 56 and the 3rd cylindric superconducting multilayer compound tube 57 and 58 that has and manage 55 and 56 same diameter D3.The 3rd cylindrical pipe 57 and 58 every length slightly are shorter than the length of second cylindrical pipe 55 and 56.As long as satisfy above-mentioned condition, the second and the 3rd cylindrical pipe 55,56 and 57,58 length can be chosen arbitrarily in a certain scope.Thereby crucial part is to improve magnetic field intensity and compares the magnetic flux that leaks out from end hole with single cylindrical pipe and stretch along central shaft 39 with the higher depth of parallelism near main or first cylindrical pipe, 54 ends.Therefore, way is to line up array like this with three kinds of different cylindrical tube of length at least preferably, makes to be reduced successively to its central length by pipe array end, with the further homogeneity of improving parallel magnetic field.

The embodiment of above-mentioned superconducting magnet apparatus is only with the principle of the present invention that lays down a definition.In other words, the those of ordinary skill in the present technique field is easy to make a large amount of modifications or improvement under the prerequisite that does not deviate from the spirit and scope of the present invention.For example, in superconducting multilayer member shown in Figure 23, it is aligned with each other that first cylindrical tube 54 and second cylindrical tube 55,56 are arranged as its end.But equally also can adopt a part that makes second cylindrical tube to stretch out the structure of the first cylindrical tube end.And, though the second cylindrical tube diameter selects greater than the first cylindrical tube diameter,, self-evident, also be feasible conversely this size relationship.And if should be noted that the pipe that constitutes superconducting magnet apparatus might not be columnar, thereby it is more consistent with the profile or the form of the object of examine or diagnosis for example also can to have an oval cross section.

In a word, in the described superconducting magnet apparatus of present embodiment, utilize two-tube configuration, it is that its direction is parallel to central shaft near cylindric superconducting multilayer component ends that magnetic flux is proofreaied and correct, compare with the single cylinder-shaped magnet that whole length direction has a same diameter thus, improved the superconducting magnet apparatus that constitutes by the superconducting multilayer member along the magnetic flux homogeneity on the whole length direction.

Figure 24 represents to produce the source according to the static magnetic field of being made by the superconducting multilayer member of another embodiment of the present invention.Among the figure, label 13 expressions are adopted the superconducting multilayer member and are had the cylindric static magnetic field generation source of central shaft 39.By adopting in the source takes place cylindric static magnetic field center the magnetic field of (sub-direction) longitudinally, realized magnetic resonance imaging system.And character Bz represents to form the direction of the magnetic flux in magnetic field.Separate surface heater part 8a has been installed on the cylindric superconducting multilayer member 13 ... 8e wherein provides the control module 9 that is used to heat the power supply P of each heater section and is used to control power supply P.

Produce in the source structure at above-mentioned cylindric static magnetic field, under superconducting multilayer member 13 magnetized prerequisites, finished the magnetic field adjusting by well heater.

When magnetization, magnetic flux direction is consistent with direction Bz shown in Figure 24, and producing continuously in the cylindric superconducting multilayer member 13 of magnetic flux has persistent current mobile along the circumferencial direction of cylinder.Usually, reduce along the Z direction by middle mind-set end face in the magnetic field in the solenoid type coil of center.Need adopt such as the way of twining the number of turns by the increase at middle mind-set two ends in order to compensate along the difference of the magnetic field intensity of Z direction.By contrast, in cylindric superconducting multilayer member 13, electric current is in the shape and the characteristic that depend on the superconducting multilayer member along the distribution on the Z direction of the whole length of cylinder-like part.Therefore, in order to proofread and correct as the distribution of current in the cylindric superconducting multilayer member of common wire wound magnet apparatus, the cylinder 13 made by superconducting multilayer member 13 should be divided into n section or part with the electric current in these sections of control after magnetization along the Z direction, thereby reach and adopt the same effect of way that increases winding turns towards cylindric coil end face direction usually.For this reason, Control current distributes so that longitudinally observe streaming current at the cylinder core less than the electric current that flows in two end portions.

By the control operation of the curve map explanation that concerns between persistent current and the temperature in the right cylinder of making by the superconducting multilayer member shown in Figure 25 A 13 according to this embodiment of the present invention.As seen from the figure, when NbTi alloy-type superconductive element is operated in following time of state by liquid helium cooling, its working temperature is usually near the scope the 4.2K that is limited by critical temperature Tc.Here should be noted that superconducting state will disappear when temperature is higher than 9K.Therefore, by Figure 25 A as seen, persistent current is got maximal value and at temperature T c place minimum value is arranged when 4.2K.Therefore, by this embodiment of the present invention as seen, at electric current in the scope of peak to peak, by changing piecemeal or the temperature of the cylinder that control superconducting multilayer member is made is controlled at the persistent current value that flows of above-mentioned cylinder section, thereby regulate the magnetic field that produces by persistent current piecemeal.Figure 25 B illustrates the control program that is used for this purpose with curve map.Particularly, can adopt heater current (1), (2) and (3) of three kinds of different sizes, have ready conditions (1)＜(2)＜(3) here.Heter temperature is proportional to heater current (1), (2) and (3) increase.Therefore, the order by (1), (2), (3) increases successively during the relative 4.2K temperature of the reduction of persistent current density.Like this, the cylinder 13 interior persistent currents of being made by the superconducting multilayer member can be adjusted to the size that needs, thereby reach purpose of the present invention.

The supposition superconducting magnet apparatus is made of the multiple layer combination cylinder in the description in front.But what should be mentioned in that is if adopt discoid superconducting multilayer member in superconducting magnet apparatus, also can reach same beneficial effect.In addition, by improving well heater installation site or number, even also can make minute adjustment to persistent current regulate under the persistent current distributed pole situation of difficult the same with the Wound-rotor type superconducting magnet apparatus.And different with the Wound-rotor type superconducting magnet apparatus is, even sometimes exceeded critical temperature Tc, also can realize steady operation, the advantage that this will provide owing to the cylinder of being made by the superconducting multilayer member 13.

And, though the superconducting multilayer member described 13 adopts the form of single cylinder, cylinder is divided into the n section, be equipped with well heater for every section, every cylindrical section is carried out above-mentioned same control also can reach same or better beneficial effect basically.

Utilize that any one can realize the magnetization of superconducting multilayer combinatorial cylinders in above-mentioned given three kinds of methods (1), (2) and (3).

Figure 26 represents the superconducting magnet apparatus according to another embodiment of the present invention.And Figure 27 is the sectional view of getting along XXVII-XXVII line among Figure 26.In these figure, part identical or equivalent with aforementioned functional or parts are marked with identical character.

In the drawings, label 11 expressions and external heat completely cut off and are divided into by dividing plate 22 low-temperature (low temperature) vessel of two coolant room 23 and 24.Fill liquid helium in the chamber 23 and 24 as the cooling medium of realizing superconductivity.Provide the inlet 25 and 26 that is used in coolant room, injecting or pouring into respectively liquid helium on the low-temperature (low temperature) vessel 11.By the superconducting multilayer member make, the cylinder 13 that produces the source as static magnetic field is put in the coolant room 23, thereby wherein cylinder or parts 13 can make supporting members support on the dividing plate 22 that liquid helium passes freely through by being anchored on the coolant channel through hole 29 that has right quantity.On the other hand, thus cylindric superconducting multilayer member 63 is positioned at coolant room 24 and by being anchored on the low-temperature (low temperature) vessel 11 and having supporting member 64 supporting that right quantity coolant channel through hole 65 is crossed the liquid helium free flow.

The field coil 16 that is electrically connected with field power supply 15 is positioned over the outside that static magnetic field produces the low-temperature (low temperature) vessel 11 in source.On the other hand, cooling medium inlet 25 links to each other with cooling medium supply source 38 with 37 by valve 36 respectively with 26.After backing out the lid of cooling medium inlet 25 and 26 and opening valve 36 and 37, liquid helium is used to promptly realize that the cooling medium of superconductivity just charges into coolant room 23 and 24 respectively.

At first, coolant room 23 is found time and be full of liquid helium in the coolant room 24.At this state, exciting current is delivered to field coil 16 by field power supply 15.Field coil 16 is a solenoid type.When exciting current flows through field coil 16, pass the ring-shaped distributed magnetic flux of field coil 16 hollow spaces and be formed for magnetized external magnetic field thereby produce.Ring-type magnetic flux have from each cylinder 13 and compensating part 63 1 ends extend out, through the inboard of cylinder 13 and compensating part 63 again to each cylinder 13 and compensating part 63 other ends and around the annular section of field coil 16 outsides.These ring-type magnetic flux produce the induction current of the cylinder 13 of along the circumferential direction flowing through.But owing to be in common conduction state, induction current decays to zero rapidly.In this case, in the compensating part of making by the superconducting multilayer member 63, induce the supercurrent that stops the magnetic flux passage according to superconducting characteristic.

Then, make coolant room 23 be full of liquid helium.Therefore, cylinder 13 is cooled to and makes it be in temperature under the superconducting state.Therefore, when the exciting current that is sent to field coil 16 when field power supply 15 dropped to zero, according to the characteristic of superconducting multilayer member, the supercurrent of magnetic flux was kept in generation cylinder 13 in, and this electric current is kept as persistent current.This magnetic flux loop wire passes central shaft 39 extensions of space 33 along cylinder 13, thereby produces static magnetic fields continuously along central shaft 39.Cylinder 13 magnetization in a single day just field coil 16 is removed from low-temperature (low temperature) vessel 11 outsides, and the space 33 that static magnetic field evenly produces can be used to place the examine object that carries out the magnetic resonance image (MRI) extraction.

Thereby the compensating part of being made by the superconducting multilayer member immerses in the cooling medium and is positioned over static magnetic field and produces between the source 13 and spools 39 and will have the latter of magnetic shielding function to be surrounded.Therefore, the magnetic flux of static magnetic field generation source 13 generations of superconducting multilayer member composition passes the two ends and the space 33 of compensating part 63.As a result, compare, be formed at space 33 interior static magnetic field homogeneitys and be improved with the structure that does not have compensating part 63.And, by suitably determining compensating part 63 size vertically, can extend or enlarge the space 33 interior evenly scopes of static magnetic field that are formed at along axle 39.

Figure 28 represents the improvement to the compensating part 63 of superconducting multilayer member shown in Figure 26.Compensating part according to this embodiment of the present invention has one group of static magnetic field correction hole 66.Thereby the part magnetic flux that static magnetic field generation source produces enters space 33 by this group static magnetic field correction hole 66 static magnetic field that is formed in the space 33 is exerted an influence.Therefore, by suitably determining distribution, quantity, the size and dimension of static magnetic field correction hole 66, can the partial correction static magnetic field, can further improve the overall homogeneity of static magnetic field thus.

Figure 29 represents the embodiment according to another superconducting magnet apparatus of the present invention.

For this superconducting magnet apparatus, the static magnetic field of superconducting multilayer member produces source 13 and is configured to a beginning sealing or partially enclosed.

According to superconducting magnet apparatus of the present invention, the cooling medium of low-temperature (low temperature) vessel 11 is interior to cover static magnetic field generation source 13 in a relative side of axle 39 with at its place, an end thereby the magnetic shielding 67 of employing superconducting multilayer member is put in.The superconducting multilayer piece table reveals the magnetic shield property that is better than common steel cage.Therefore, magnetic shielding 67 can effectively suppress from static magnetic field the magnetic field that leak in source 13 to take place.Particularly in the front of magnetic shielding 67 perforates, though can't suppress fully can effectively prevent the leakage of magnetic flux to magnetic shielding 67 spherical part 67a rear sides to the magnetic field of front side leakage.Therefore, the rear space of spherical part 67a (promptly in an extreme example in the space of perforate back) can be used as field-free space and is used.

By in low-temperature (low temperature) vessel 11, providing dividing plate magnetic shielding 67 is placed in first coolant room, static magnetic field is produced source 13 be put in second coolant room, can be independent of second coolant room and first cavity is found time or be full of liquid helium.In this configuration, can eliminate the influence of magnetic shielding 67 excitations fully.

As the improvement of superconducting magnet apparatus, can shield the structure of cover and adopt the structure that produces source 13 both ends opens with the same static magnetic field of superconducting magnet apparatus shown in Figure 1A in magnetic field shown in Figure 29.

Figure 30 and 31 represents respectively according to the other embodiment of superconducting magnet apparatus of the present invention.

In superconducting magnet apparatus shown in Figure 30, near the center of the spheroid part 67a of magnetic shielding 67, have a size and examine object xsect corresponding opening.This structure is very outstanding for opening wide, ventilate and throwing light on.In others, device shown in Figure 30 structure with shown in Figure 29 basically is identical.On the other hand, in superconducting magnet apparatus shown in Figure 31, be furnished with optical reflector or mirror 68 in the end of aforementioned magnetic shielding 67.By optical reflector such as mirror 68 is provided by this way, exteriorly getting up can the extending space degree of depth, thereby has increased the opening character in space.Certainly, the space that also can replace optical reflector to throw light on holding the examine object with light fixture.Except providing the space illumination with the device, other structure is the same with superconducting magnet apparatus shown in Figure 29 with operation.

Figure 32 is the schematic block diagram of magnetic resonance imaging system hardware configuration, and wherein the superconducting multilayer member produces the source as static magnetic field.The object 71 of examine or diagnosis is put in the static magnetic field of superconducting magnet apparatus 72 generations that comprise the static magnetic field generation source of adopting the superconducting multilayer unitized construction.The high-frequency impulse that high frequency pulse generator 73 produces is sent to T-R coil 75 after amplifier 74 amplifies, object under test 71 is under the electromagenetic wave radiation.Therefore in the object 71 of examine, excited nuclear spin.The NMR signal that the nuclear spin that examine object 71 excites by this way produces is sent to receiver 77 after T-R coil 75 detects.Thereby gradient magnetic controller 78 control gradient magnetics produce coil 76 and make specific aspect to produce gradient magnetic on X, Y and Z direction.These gradient magnetics are superimposed on the static magnetic field.

Sequence controller 79 links to each other with gradient magnetic controller 78, high frequency pulse generator 73 and receiver 77, is used to control according to predetermined pulse train produce high-frequency pulse signal, be used to control the gradient magnetic and the NMR signal reception sequential that produce on X, Y and the Z direction.And under the control of sequence controller 79, computing machine 80 carries out image reconstruction process according to the NMR signal that receiver 77 receives, and by the control desk 81 that is used for control information/data transmission the result is presented at display unit 82.

Realize that at employing superconducting multilayer member shown in Figure 32 static magnetic field produces in the magnetic resonance imaging system in source, can carry out multiple pulse train known such as various spin-echo methods, two-dimentional echo method etc. and obtain x-ray tomography images.And the magnetic resonance imaging system that adopts the static magnetic field of being realized by the superconducting multilayer member to produce the source can extract x-ray tomography images by means of the various pulse trains that will develop.

Claims (6)

1. one kind has the superconducting magnet apparatus that holds therein as the low-temperature (low temperature) vessel of the cooling medium of realizing superconductivity, comprise the magnetic flux generation device that is contained in the described low-temperature (low temperature) vessel and be used for described magnetic flux generation device is fixed on the device of described low-temperature (low temperature) vessel, it is characterized in that this superconducting magnet apparatus also comprises:

Constitute one and be used to keep the superconducting multilayer member of keeping medium that produces a persistent current of magnetic flux along the axis direction of predetermined magnetic field space.

2. superconducting magnet apparatus as claimed in claim 1 is characterized in that, described magnetic flux generation device comprises having its axis cylindric superconducting multilayer member consistent with the described axis of described predetermined magnetic field space.

3. superconducting magnet apparatus as claimed in claim 1 is characterized in that, described magnetic flux generation device comprises the quadrature installation of a plurality of and described axis, and has the flat superconducting Mnltilayered structures of through hole around described axis.

4. superconducting magnet apparatus as claimed in claim 2 is characterized in that, described superconducting multilayer member is near the diameter at those positions of the one end diameter less than its core.

5. superconducting magnet apparatus as claimed in claim 2, it is characterized in that, described magnetic flux generation device has three cylindric superconducting multilayer members with mutually different diameter at least, and described at least three superconducting multilayer members are mounted to an array like this, thereby described diameter reduces gradually along the direction of core to its end from described array.

6. superconducting magnet apparatus as claimed in claim 2 is characterized in that described magnetic flux generation device comprises: the first cylindric superconducting multilayer member with first diameter; And

The second cylindric superconducting multilayer member that at least one partly overlaps with the first cylindric superconducting multilayer member in coaxial circumference array, the length that the described second cylindric superconducting multilayer member has is shorter than the length of the described first cylindric superconducting multilayer member.Temperature and under this state, produce the described magnetic flux of described predetermined value; And

Again described superconducting multilayer member is adjusted to superconducting state again, under this state, produces the described magnetic flux of described predetermined value.

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