JPH02503048A - A coil, a magnet including the coil, an NMR imaging device including the magnet, and a method for making the magnet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] A coil, a magnet including the coil, an NMR imaging device including the magnet, and a magnet including the magnet. How to make The present invention was developed by the National Institute for High Magnetic Fields (Director Nio) of C,N, R,S (France). -Bitter type coil, The present invention relates to a magnet including a coil and a nuclear magnetic resonance imaging device equipped with the magnet. Ru. Furthermore, the present invention relates to a method of making the above-mentioned magnet. specifically In other words, the present invention improves the uniformity of the generated magnetic field and simplifies the production of magnets. This invention relates to an improvement of the above-mentioned type of magnet.

The Bitter-type coil was published in the December 1936 “Review of Chemical Equipment”. Francis in a paper published in ``5Ccientific Instruments''. It was first announced by Francis BITTER. Each The coil is a nearly round shape with slotted and flat turns to form turns. It has a metal disk mounted to define a spiral winding. Are known Bitter-type coils are made of insulating material inserted between metal discs to prevent short circuits. and a tie rod for maintaining the stacked state. Furthermore, the axis of the coil Multiple openings of the same shape are set parallel to each other, and a set of parallel channels passing between the metal discs constitutes a channel. Fluid circulates through these channels to effectively cool the magnet. reject

A Bitter-type magnet includes at least one Bitter-type coil.

Many improvements have been made to these Bitter magnets.

French patent application published under French patent application publication number 2574982 Application No. 84-19193 proposes a current return path using tie rods that secure the device. Discloses a bitter type magnet comprising a. Therefore, the current flow is It is distributed in the longitudinal direction on a cylindrical surface coaxial with . This current flow is carried by the lead wire conductor. This cancels out the stray magnetic fields that occur.

French patent application published under French patent application publication number 2574980 Application No. 84-19191 minimizes the product P-M while obtaining the desired magnetic field uniformity. It discloses how to do this. Here, P represents the power supplied to the magnet, and M represents the power supplied to the magnet. Represents the mass of the stone winding.

Several bitter-type coils are arranged along a common longitudinal axis 2 and symmetrically with respect to the cross section. Optimization can be achieved by placing by generating a spatially harmonized magnetic field. The characteristics and arrangement of the coil are such that magnetic field inhomogeneities can be compensated for as completely as possible. The location can be determined. This correction can be made in the axial and/or radial direction inside the device. Constraints such as temperature gradients in the direction can also be considered.

In fact, when the coil heats up, either globally or locally, the generated magnetic field Geometric changes due to expansion and changes in resistance of the metal forming the coil due to temperature. , and thus changes due to changes in the current flowing through different parts of the coil. choose In order to determine the ideal coil and its positioning, taking into account the constraints Preferably, calculations can be made by computer.

For magnets determined by the already proposed method, the product P-M is given by the formula %formula% However, %Be is the magnetic field expressed in Tesla μ. is a constant a is the inner diameter of the device p is the density of the metal forming the helical winding ρ is the resistance of the metal forming the helical winding The degree g is a geometric factor that determines the uniformity of the magnetic field, and is a value less than 1 (cross-sectional area is zero). is given by 1) for a single turn of .

The constraints imposed allow the configuration to be determined accurately.

It is useful to consider the effect of temperature on the properties of the magnet.

That is, during operation, constraints are imposed on the magnets that have reached temperature parallelism.

Furthermore, the restrictions imposed vary depending on the use of the magnet. For example, current economic conditions Below, it is often convenient to use copper to construct the coil.

For example, the following items are required for an NMR imaging device.

・Magnetic field from 0.1 Tesla to 1 Tesla -Inner diameter that can accommodate the patient and the magnetic device that needs to be inside the magnet ・Maximum uniformity of the generated magnetic field with a geometric shape where the factor g is less than 1 sex On the other hand, in the field of scientific research, magnets are required to:

・Generation of the maximum possible magnetic field, e.g. 10 Tesla or more. ・Accommodating samples subjected to magnetic fields. Small inner diameter and high uniformity of generated magnetic field Optimization methods determine the exact geometry the coil will take to obtain the desired magnetic field can do. However, the accuracy of Bitter-type coils is limited. So Therefore, an object of the present invention is to be able to improve the accuracy of creating a bitter-type coil, and in particular to The objective is to provide a method that can approach the optimal model calculated by calculation.

For that purpose, holes through the windings of the coil were eliminated. Such holes are suitable for carp Preferably, the cooling channels are replaced by external and/or internal cooling channels.

The elimination of holes allows the coils to be connected insulatively so that each coil is an integral part. Can be joined using adhesive material. If there is a hole in the metal disc, the adhesive will enter the hole. Adhesives cannot be used as they will prevent proper cooling of the embedded coil. of the reason The first is that the adhesive impedes heat exchange between the metal disc and the cooling fluid; This is because the adhesive partially clogs the pores, restricting fluid flow.

The adhesive that has flowed into the inside and outside of the coil can be mechanically processed, e.g. using a lathe. can be effectively removed. Therefore, the finished coil is mechanically Since it has the precision of a machine part, it can be fixed with a tie rod and used as a bitter type coil. can have higher accuracy than that obtained with . Machining involves machining the coil. This can be achieved by making it an integral part that can be machined. Furthermore, the adhesive is The device can be simplified compared to known devices.

As described in the claims, the present invention relates to a coil, a magnet including the coil, and a magnet including the coil. The present invention relates to a nuclear magnetic resonance imaging apparatus equipped with a magnet, and a method for manufacturing the magnet.

The invention can be understood more clearly from the following description and drawings, given by way of non-limiting example. There will be.

FIG. 1 is a drawing of a first embodiment of a coil according to the invention, and FIG. 2 is a drawing of a first embodiment of a coil according to the invention. 3 is a drawing of a second embodiment of the coil according to the present invention, and FIG. 3 is a drawing of a third embodiment of the coil according to the present invention. FIG. 4 is a drawing of a fourth embodiment of a coil according to the present invention; Figure 5 is a diagram showing the temperature characteristics of the coil shown in Figure 1, and Figure 6 is a diagram showing the temperature characteristics of the coil shown in Figure 2. FIG. 7 is a diagram showing the temperature characteristics of the coil shown in FIG. FIG. A diagram of the operation, FIG. 9 is a diagram of an apparatus for making a coil according to the invention, and FIG. 10 is a diagram of an apparatus for making a coil according to the invention. FIG. 11 is a detailed view of an embodiment of a coil according to the present invention; FIG. 13 is a diagram of a magnet according to the invention, and FIG. 14 is a detailed view of an example. 1 is a diagram of an embodiment of a nuclear magnetic resonance imaging device according to the invention, FIG. 15 is a diagram of a cooling device used in a nuclear magnetic resonance imaging apparatus according to the present invention. , FIG. 16 is a diagram of a cooling device used in a nuclear magnetic resonance imaging apparatus according to the present invention. .

Identical elements in FIGS. 1 to 16 are given the same reference numerals.

FIG. 1 shows a coil 1 according to the invention without holes for cooling. Koi The coil 1 is a Bitter-type coil comprising a plurality of discs 3 with slots. Disk 2 A discontinuity 5 connects each disc to the next so that the continuum of discs is substantially free. It forms a spiral coil.

Since there are no holes for cooling, it is possible to assemble the disk 3 using insulating adhesive. Wear. However, it is necessary to cool the coil. In the embodiment of FIG. , has a cylindrical external cooling channel 2 with an axis 2 coaxial with the axis of the coil 1. Ru.

The use of adhesive 4 makes it possible to create an integral coil 1 that can be machined. subordinate (not shown in the example in Fig. 1). ) The adhesive can be removed by machining. If there are cooling holes , after the adhesive 4 extrudes, it must be machined or re-machined. Will.

The use of external cooling channels 2 around the coil allows the center of the coil to This frees up more space available for accommodating objects subject to the magnetic field. follow In this way, the dimensions of the coil 1 can be reduced or the available space can be increased. . For example, in the field of nuclear magnetic resonance imaging applications, the patient, radio frequency antenna, gradient The field generating coil, and possibly the correction coil, must be housed inside coil 1. Must be. Here, as mentioned above, the product P-M is proportional to the fourth power of the inner diameter of the coil. I want you to remember that.

FIG. 2 illustrates a coil 1 according to the invention with internal cooling channels 2 . In this embodiment, the cooling channel 2 absorbs most of the heat generated by the Joule effect. located closer to the area where the minute occurs. Therefore, the generated heat is inside the disk 3. is almost completely removed.

FIG. 3 shows an embodiment according to the invention having an internal cooling channel 2 and an external cooling channel 2. The coil 1 shown in FIG. This embodiment allows particularly efficient cooling of the coil It is.

Note that various measures can be taken to improve the cooling efficiency of the coil 1.

Figure 4 shows a channel for cooling fluid, mounted helically around coil 1. A part 7, for example an insulating bar, is shown defining a wall 7. Therefore, the cooling fluid It takes a long route around the tube 1 several times to achieve effective cooling. coil The shape of the channel 7 is designed to prevent the formation of a boundary layer that would impede effective cooling of the , causing turbulence.

When a boundary layer forms, proper cooling is particularly hindered due to the poor thermal conductivity of the fluid. Ru.

FIG. 5 shows the characteristic 10 of the temperature T inside the metal disk 3 (axis indicated by reference numeral 9) with radius It is shown as a function of r (axis indicated by reference numeral 8). The temperature characteristics in Figure 5 are It corresponds to the external cooling channel 2 shown in the figure. As the radius 8 increases, the temperature 9 decreases to the lowest temperature at the edge of the disk 3.

In order to achieve a uniform magnetic field, during the optimization process, it is necessary to expansion of the inner bore of the coil 1 according to the invention and various parts of the disc of the coil 1 It is necessary to take into account the variation in resistivity at Regarding temperature, heat conductive surfaces Calculate using the heat balance formula, taking into account the conditions, specific heat conditions, and cooling fluid flow rate. This can be determined by

FIG. 6 shows the temperature T (see The characteristic 10 of the axis denoted by reference number 9) is shown as a function of the radius r (axis denoted by reference number 8). ing.

In the case of characteristic 10 shown in Fig. 6, the lowest temperature is at the inner edge of the disk 3, and the highest temperature is at the outer edge. The temperature gradually increases until .

FIG. 7 shows the temperature T (see The characteristic 10 of the axis denoted by reference number 9) is shown as a function of the radius r (axis denoted by reference number 8). ing. The coil 1 shown in Figure 3 has an external or outer cooling channel and an internal cooling channel. It has a cooling channel. The lowest temperature is at the inner and outer edges of the disk 3.

From the lowest temperature, the temperature increases towards the inside of the disk 3 and reaches the maximum temperature. .

The temperature characteristics shown in FIGS. 5, 6, and 7 correspond to the disk 3. Addition of cooling fluid From the thermal gradient, a cooling fluid with such a heating gradient circulates through the cooling channels. It is possible to determine the temperature gradient along axis 2 when

In the first embodiment of the Bitter-type coil, the electrical circuit consists of mechanical connections between the disks 3 and This was achieved through close contact. The improved bitter type magnet is made by partially making a metal disk in half. It was made by plating.

The method for soldering by indium electrodeposition is French patent application publication number 25780. Disclosed in French Patent Application No. 85-02971 published under No. 57 Ru.

FIG. 8 shows an example of direct bonding of copper to copper. two discs 3 together or disc 3 0 Direct joining of the two parts creates a convex part 32 on one side of the disc, and a convex part 32 on the other side A recess 33 is formed on the surface of the disk, and that portion is where the disk begins and ends. The convex part is a joint Occurs as a result of shrinkage of copper due to the heat generated during operation.

The presence of the protrusions 32 hinders the creation of a smooth coil 1. That is, The protrusions 32 disturb the uniformity of the magnetic field generated by the magnet according to the invention and furthermore There is a risk of damaging the insulation between the plates.

Furthermore, at the joint 31, if the disk is a perfect circle, the circular axis 34 of the disk and the point of the disk are A deformation angle α may occur between the circular axis 33 of the part and the circular axis 33 of the part.

The device shown in Figure 9 can solve the problems caused by direct bonding of copper to copper. Ru. For example, it is not possible to perform industrial machining to remove the convex portion 32. . Therefore, this machining process should always be performed before applying the adhesive 4. mechanical processing The cutting edge of the cutting edge may puncture the adhesive material 4 and prevent the coil from working perfectly. may occur.

In comparison, the protrusion 32 is flattened by applying a pressure roller from above. I found out that it is possible.

The device of FIG. 9 comprises two pressure rollers 36, for example mounted on the ends of two arms 37. It is equipped with two attached ball bearings. For example, the control device has two arms 37 attached to one arm of the arm and screwed into a threaded hole in the other arm to provide two pressure It is a threaded steel rod that allows the distance between the rollers to be adjusted. Therefore, the joint In addition to flattening the convex portion 32 of 31, apply a large amount of pressure to the convex portion. Accordingly, the mismatch between the axes 34 and 35 can be corrected. After flattening, join The part 31 partially fills the recess 33 at the end of the joining operation, and the remaining defects are removed using a lathe. removed by final machining.

FIG. 10 shows a particularly advantageous connection made to create a coil according to the invention. Illustrated how to wear it. In the example shown in FIG. 10, only two discs 3 are shown.

In this embodiment, the portion of the disk 3 to be joined corresponds to the 11th dot. This value is , approximately corresponds to 1/3 of one turn, and prevents the joints 31 from systematically overlapping. It is something that In the example shown in FIG. 10, the adhesive 4 consists of two layers. each layer is off by half a pitch. There is a gap 60 in each layer, and the space is filled with adhesive. Filled with adhesive as it polymerizes. Manufactured by ISOVOLTA Adhesive material sold by DEGLARGES Prinom B J is used with a thickness of 0.1 mm.

An offset of 600 and a half pitches in the gap ensures good insulation after polymerization. It will be done. Additionally, the adhesive reduces the winding required in the case of magnets used in NMR imagers. It is possible to realize the voltage resistance between cycles without any difficulty. For example, a magnetic field with a number of turns of 500 In this case, the voltage between the first turn and the last turn is 200V. Furthermore, the adhesive If it is a surface adhesive type, it has excellent mechanical strength and the coil 1 realized by adhesive material. Allows for machining. Please note that the above adhesive is very abrasive and may cause damage to diamonds. The need to change machining tools frequently unless Mondo tools are used. I would like to point out that.

FIG. 11 illustrates two examples of machining of a coil 1 according to the invention. Circle A Inside, the resulting machining is smooth. This machining process is easily achieved can do. Optimization calculations are easier to perform if a simple surface is used.

Within circle B there is a groove 80. These grooves form static boundaries of the fluid on the surface of the coil 1. Prevents the formation of an interfacial layer and facilitates cooling. Unlike the example shown in Figure 11, , a single type of machining can be applied to the surface of the coil 1. But long The surface defining the cooling channels 2, not shown in FIG. Surfaces that are processed and not cooled can also be machined smooth.

FIG. 12 illustrates a coil 1 according to the invention with an insulating rod 30. FIG. Insulating rod 3 0 functions as a spacer between the coil 10 body and, for example, the frame of the magnet.

The insulating rod 30 is bonded, for example, with an adhesive after the coil 1 is machined. insulation rod If 30 is not available, there is a risk of scratching the coil 1 when attaching it to the magnet frame. be. This problem is particularly acute when fiberglass frames are used.

It also creates scratches in the copper that, if rubbed, can short out the windings, causing the magnet to become uniformly magnetic. It can also make the field unsuitable for generation.

FIG. 13 illustrates a method of incorporating magnets according to the invention.

The magnet frame according to the present invention is composed of two half frames 61 having an opening in the horizontal direction. Ru.

In the lower half-frame place the first complete coil 1 according to the invention. Then the center The guide tube 62 is advanced. This tube 62 is made of, for example, glass fiber reinforced epoxy resin. It is effective to make it with fat.

A spacer 64 or shims is installed. of the magnetic field generated by the coil In order not to disturb the uniformity in any way, the spacer 64 is It is advantageous to provide a connection to the coil 1. This coil connection is made in France French Patent Application No. 85 published under Patent Application Publication No. 2579362 -04050 and published under French Patent Application Publication No. 2581760. It is disclosed in French Patent Application No. 87-07151.

Furthermore, the central guide tube 62 is advanced.

The second coil 1 is placed in the lower half-frame 61.

Connect the first and second coils 1.

The central guide tube 62 is advanced until a complete magnet is completed, and the next spacer 64 and Repeat the operation of attaching coil 1 and connecting.

The spacer 64 ensures watertightness of the cooling channel 2 (not shown in FIG. 13). It is effective to

Note that in FIG. 13, the central guide tube 62 is shown as being at its end position. Ru.

After the coil and spacer are installed, a current return connection is made, e.g. around the magnet. This is done by placing copper cables in order to avoid creating any disturbing magnetic fields. Ru. The magnet is then closed by the upper half-frame 61 and assembled with the end flange 63. Put on.

For the connections, any necessary metallurgical treatment, e.g. deposition of a nickel diffusion prevention layer, Treatments such as the application of a gold layer to prevent corrosion would be obvious.

After the frame is installed, it effectively makes the magnet 1 watertight and also provides cooling channels. effectively functions as a wall for channel 2.

The use of the spacer 64 is due to the accuracy of the coil 1 of the optimized magnet embodiment determined by calculation. positioning.

FIG. 14 illustrates an imaging device based on image magnetic resonance. The device is in a magnetic environment A known shim (not shown) essentially configured to compensate for the disturbing magnetic field A correction coil system is provided. A magnetic field with the function of forming the main magnetic field The stone is equipped with known gradient coils 50. The gradient coil is coaxial with axis 2. , provided on a cylindrical mandrel disposed within the internal space 12 of the magnet 11 . The gradient coil system is powered by a DC power source (GX, Gy, Gz). that The DC power supply is supplied with cycles in a sequence preprogrammed in the computer 51. during the above sequence to supply power to the gradient coils at a given intensity and direction. A magnetic field gradient is superimposed on the main magnetic field. Selection of cross-section for image reconstruction using gradient magnetic field becomes possible. A radio frequency antenna 55 is located inside the effective space 12 of the magnet 11. It is located. An antenna forms part of the means for transmitting and receiving radio frequencies; The radio frequency transmitting/receiving means transmits the radio frequency signal calibrated during the above sequence. a radio frequency generator controlled by computer 51 to generate signal pulses; It is equipped with a container 56. During testing, the NMR signal re-emitted from the subject is the same Applying known algorithms to reconstruct the images received by the antenna system, Processed by a calculation unit of computer 51. This image is, for example, a cathode ray The image is displayed on a tube-type monitor 58. The imaging device further includes a tube 14, a pump 17, a heat A cooling circuit including an exchanger 16 is provided. Reference number 16a is the primary of the heat exchanger The circuit is shown, reference numeral 16b designating the secondary circuit of the heat exchanger.

Preferably, the NMR imaging device is as described in French Patent Application Publication No. 2574982. As disclosed in French Patent Application No. 84-19190 published by is equipped with an adjustment device. A device similar to that of the patent application includes a small auxiliary magnet 13 and , a cooling fluid circulation circuit 14 in thermal contact with magnets 11 and 13, and two magnets. and a DC source 15 connected in series to the coil.

In any case, the magnet 11 is placed between the windings of the respective resistive coil and the cooling fluid. It has a structure that enables efficient heat exchange. The same thing applies to magnets. the cooling fluid so that it is always at substantially the same temperature of the main magnet. The magnets are also laid out to receive the magnets. In this regard, the inside of the auxiliary magnet The resistance is very small compared to the internal resistance of the main magnet, and the resistance is very small compared to the internal resistance of the main magnet. The effect of the auxiliary magnet on body heating is negligible. The two magnets 11 and 13 The coils are made of the same conductive material, especially copper or aluminum.

The cooling circuit 14 includes a circulation pump 17 and a heat exchanger 16. The heat exchanger 1 The above-mentioned cooling fluid circulates in the primary circuit 16a of No. 6, and the secondary circuit 16b has the cooling fluid circulating therein. , e.g. cold water is supplied. In the illustrated example, all of the cooling fluid flows through the auxiliary magnet 13. The cooling circuit is configured to allow fluid flow. However - the temperature of magnet 13 is Only a portion of the cooling fluid circulates through the magnet 13 so that the temperature is substantially equal at all times. A suitable bypass path may be provided. In this concept, the magnet 13 is supplied with The cooling fluid is sent directly from the main magnet 11 without going through the heat exchanger 16. It is particularly important to determine the layout of the sea urchin cooling circuit 14.

Furthermore, as mentioned above, the coils of magnets 11 and 13 are always supplied by current source 15. The same current flows. The magnet 13 has a function of generating a reference magnetic field representing the main magnetic field. are doing. In at least one confined volume of the internal space of the magnet 13, a reference Means for measuring the magnetic field are arranged. The measuring means is a direct current source 15. The automatic control device 19 controls the current supplied to the device.

According to a preferred embodiment, the magnetic field measuring means is an NMR device controlling the automatic control device 19. A probe 20 is provided. The NMR probe 20 has the above-mentioned limited placed within a volumetric space. To acquire a usable NMR signal, auxiliary magnet 1 3 is incorporated to ensure sufficient uniformity within the confined volume space in which the probe is placed. A reference magnetic field is created having the following values. In fact, the reference in the volumetric space surrounding the probe The homogeneity of the magnetic field is 1 pp, which is the same magnitude as the homogeneity of the main magnetic field within the effective volume of the main magnet. m to 10 ppm.

Magnets 11 and 13 have longitudinal symmetry axes 02 and ○°2°, respectively. . 0 and 0° are the centers of symmetry of each magnet. Advantageous features of the invention According to and intersects axis O2 at point O. Of course, the magnet 13 itself is located outside the magnet 11. This arrangement eliminates parasitic coupling between the two magnets. can minimize the coincidence and therefore minimize the disturbance of the homogeneity of the two magnetic fields. can be done.

15 and 16 show an implementation of a cooling device 02 for a magnet 11 according to the invention. An example is illustrated.

FIG. 15 shows a magnet 11 with a primary circuit of fluid and a secondary circuit. − The secondary circuit provides thermal energy to the secondary circuit by means of a heat exchanger 16. Preferably, A pump 17 circulates the primary cooling fluid.

The magnet 11 according to the invention has a very wide field of application.

Depending on the field of application, the technical properties and economic constraints of magnets are quite different. specified It is important to adapt the cooling method to the type of magnet being used and the economic constraints. Ru.

In the field of scientific research, strong magnetic fields often exceeding 10 Tesla are generated. Magnets that can be used are used. Such a magnet is passed through a very strong current, and its lifespan is is often limited to, for example, 1000 operating hours. In such application fields, It is often effective to use deionized water as the cooling fluid. This fluid is , has the advantages of very high specific heat, low viscosity, and high resistance. On the other hand, leaving Ionized water is difficult to prepare deionized water and is corrosive to copper. It also has some drawbacks, such as: However, corrosion caused by deionized water In any case, during the lifetime of the magnet, which is limited to 1000 hours, it will not become detectable. Not possible. In the field of scientific research, relatively high pressures, e.g. 30 bar pressure is frequently used to increase the flow rate of cooling fluid.

In the field of medical imaging, it is preferred to use kerosene or oil as the cooling fluid. It's convenient. These fluids are neutral to copper, which is useful for constructing coils.

Additionally, these fluids can be stored for long periods of time and are easy to use. anti On the other hand, the disadvantages of these fluids are their low specific heat and high viscosity. These drawbacks are , the magnetic field to be generated is typically around 0.1 Tesla compared to the case of scientific research. Because sea urchins are weak, and the cooling efficiency can be increased by using the mainstream as shown in Figure 4. Provide equipment or equipment for body flow, so that it is acceptable for NMR imaging. Ru.

French patent application No. 84-1 filed on July 10, 1987, which has not yet been published. No. 9191 discloses the use of latent heat from phase transitions for cooling magnets. child The latent heat due to the phase transition corresponds to, for example, when the cooling fluid changes from the liquid phase to the gas phase. do. Contains both phases, e.g. liquid and gas, everywhere along the cooling circuit By using a fluid it is possible to eliminate the temperature gradient along the axis 2 of the magnet 11. Ru. Furthermore, the very large absorbed energy per unit mass reduces the cooling fluid flow rate. can be restricted. Many dielectric fluids are suitable for this type of cooling.

- for the patient located inside the magnet 11 at the pressure used in the cooling circuit; It is advantageous to use a cooling medium with a boiling temperature that does not cause any disadvantages. . For example, Freon 11 composed of CC15F is heated at 30°C under a pressure of 1.3 bar. is the boiling temperature of

Figure 16 shows a magnet 11 that uses a heat pump to remove heat from the magnet. 3 is another embodiment of a cooling device. A heat pump is a compressor placed in the primary circuit. 170 and a pressure reducing valve 171. By using a heat pump, heat exchanger 16 The amount of water flowing can be reduced.

It is convenient if the cooling circuit inside the magnet 11 constitutes at least a part of the pressure reducing valve 171. Good.

The present invention is mainly suitable for producing a bitter-type coil 1 and a bitter-type magnet 11. can be used. However, the present invention does not apply to scientific or medical research and nuclear magnetic collaboration. It is particularly applicable when obtaining strong and/or uniform magnetic fields for sound imaging.

FIG. 15 Submission of translation of written amendment (Article 184-8 of the Patent Law) April 9, 1990

Claims (1)

[Claims] (1) A plurality of metal discs (3) provided with slots to form a winding part. and connected such that the metal discs constitute a substantially helical winding along axis z. and the flat winding has at least one cold winding that can guide the fluid. In the bitter-type coil (1) passing through the cooling channel, the spiral winding characterized in that it is equipped with a cylindrical cooling channel (2) having an axis z coaxial with coil. (2) The ends of the disk (3) or a part of the disk are joined by copper bonding. 2. The coil according to claim 1, wherein the coil is assembled in a manner such that the coil is assembled in a manner that (3) The outer surface of said winding constitutes the inner wall of said cooling channel (2). parallel to the outer surface of said winding and having a larger diameter compared to the outer surface of said winding. forming an outer wall of the cooling channel (2). The coil according to claim 1 or 2. (4) The inner surface of said winding constitutes the outer wall of said cooling channel (2). parallel to the inner surface of said turn and of a smaller diameter than the outer surface of said turn. forming an inner wall of the cooling channel (2). The coil according to claim 1, 2 or 3. (5) The metal disk (3) is bonded with an insulating adhesive (4). The coil according to claim 1, 2, 3 or 4, characterized in that the coil has the following characteristics: (6) The adhesive material (4) according to claim 5, wherein the adhesive material (4) is a polymerizable adhesive material. coil. (7) have a region that overlaps the corresponding gap (60) of the disc before polymerization; The adhesive material (4) is characterized in that it has two disks having a discontinuous portion. The coil according to claim 6. (8) Claims 5 and 6, wherein the adhesive (4) is PrinomB. Or the coil described in 7. (9) Claim 1 characterized in that it has an almost perfect cylindrical shape by machining. , 2, 3, 4, 5, 6, 7 or 8. (10) The surface receiving the cooling fluid should prevent the formation of a boundary layer of the cooling fluid. Claims 1, 2, 3, 4, 5, characterized in that it has a groove (80) that allows The coil according to item 6, 7 or 8. (11) At least one coil according to any of the above claims is provided. A magnet characterized by. (12) All coils (13a-13b, 14a-14b, 15a-15b) are , have substantially the same inner and outer diameters, and the same current flows through all coils. The length of the coil, the axial separation distance between the coils, and the outer diameter has the optimal force/mass product and makes the magnetic field uniform in the region of interest. 12. The magnet according to claim 11, wherein: (13) The coil (1) comprises a central tube (62) around which the coil (1) is arranged. The magnet according to claim 11 or 12. (14) Between the two coils (1), around the central tube (62), Cylindrical spacer (64) or multiple shims that can be precisely positioned relative to each other 14. The magnet according to claim 13, wherein the magnet has: (15) The spacer (64) is a conductor for connecting the coils (1) in series. 12. The magnet according to claim 11, further comprising a passageway extending through the magnet. (16) Two elements (61) that can be assembled along a plane including the axis z Claim 11, 12, 13 or 14, wherein the frame is formed by Magnet as described. (17) The wall of the frame forms an outer wall of the cooling channel (2) of the coil (1). The magnet according to claim 11, 12, 13, 14 or 15, characterized in that stone. (18) The geometry of the cooling channel (2) makes the cooling fluid turbulent. Claims 11, 12, 13, 14, 15 characterized in that: , 16 or 17. (19) Forcing the cooling to increase the flow path within the cooling channel (2). Claim characterized in that the cooling channel (2) has a helical section inside the cooling channel (2). The magnet according to item 11, 12, 13, 14, 15, 16, 17 or 18. (20) The frame and the central tube (62) are made of a plastic material containing fibers. Claims 11, 12, 13, 14, 15, 1, characterized in that it is made from 6, 17, 18 or 19. (21) Configure a current return path to one of the axial ends of the magnet, and The arrangement and/or arrangement is such that the current is distributed in the longitudinal direction on the cylindrical surface coaxial with the coil (1). at least one conductor (119) in the shape of Claim 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 magnet. (22) The conductor (119) constituting the current return path is made of copper or aluminum. 22. A magnet according to claim 21, characterized in that it is made of: (23) Claims 10, 11, 12, 13, 14, 15, 16, 17, 18 and or 20. A nuclear magnetic resonance imaging apparatus characterized by comprising the magnet according to 19. (24) Auxiliary magnet thermally coupled to the cooling fluid circuit and supplied with power from the power supply means The auxiliary magnet represents a main magnetic field in a limited volume space. The auxiliary magnet is smaller than the main magnet to generate a reference magnetic field, and the auxiliary magnet is smaller than the main magnet. , a small number of coils according to claims 1, 2, 3, 4, 5, 5, 7, 8, 9 or 10. In addition, the nuclear magnetic resonance imaging apparatus has at least one means for measuring the reference magnetic field generated between the reference magnetic fields; Claim 1, further comprising means for automatically controlling said power feeding means. 1. The nuclear magnetic resonance imaging apparatus according to 1. (25) Disconnect the disc (3) or part of the disc (3) forming the helical coil (1). A method for producing a magnet characterized by bonding with an edge adhesive (4). (26) Disc (3) or part of disc (3) forming helical coil (1) 26. The method for producing a magnet according to claim 25, wherein the magnets are joined end to end. (27) The magnet according to claim 26, wherein the bonding is a bonding of copper to copper. How to create. (28) Claim 26, wherein the joining is indium soldering. How to make a magnet. (29) Machining the inner and/or outer surfaces of the coil (1) using a lathe. The method for producing a magnet according to claim 25, 26, 27 or 28, characterized by: (30) A claim characterized in that a smooth cylindrical surface is created by the machining. 29. The method for producing a magnet according to 29. (31) The above machining process can prevent the formation of a stationary boundary layer of the cooling fluid. 31. A magnet according to claim 29 or 30, characterized in that it creates a grooved surface that can How to make. (32) Mounting the coil (1) on the central tube (62) and 2) A claim characterized in that the operation of attaching the spacer (64) on the top is performed alternately. The method for producing a magnet according to item 25, 26, 27, 28, 30 or 31. (33) The dimensions of the central tube and the spacer are the product P・M (where P is the magnet (11) and M is the power supplied to the magnet (11) for the required magnetic field homogeneity. The mass of the conductor is optimized. 32. The method for producing a magnet as described in 32.