JPH01302806A - Superconductive coil - Google Patents

Abstract

PURPOSE:To make it possible to form a magnetic field having a high uniformity through a simple operation by a method wherein a cylinder with a screw is mounted rotatably around the axis of a main coil on the main coil and subcoils are provided on a cylindrical member engaging the screw of the cylinder respectively. CONSTITUTION:In a superconductive coil provided with subcoils 3, 5 having axial length shorter than the above axial length at both ends of a main coil 1 having a predetermined length of axis length, rotary cylinders 49, 50 with screws 41, 51 are mounted rotatably around the axis of the main coil 1. Subcoils 3, 5 are positioned in cylinder members 60, 70 engaging the screws 41, 51 of the rotary cylinders 40, 50 respectively. The cylinder members 60, 70 are locked to the main coil 1 side via swivel stopping mechanisms 22, 61. As a result, an axial relative position of the main coil and the subcoil can be finely adjusted by using a combination of a cylinder and a screw. Therefore, by connecting both coils in series and energizing them with a single power supply, a magnetic field having a high uniformity can be obtained through a simple operation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the use of NMR (Nuclear Magnet).
ic Rcsonance-Nuclear Magnetic Resonance) analysis, or MRI (Magnetic Resonance) analysis.
The present invention relates to superconducting coils used for imaging (magnetic resonance imaging) and the like.

[Prior Art] For example, a superconducting coil for analysis in an NMR device includes a solenoid coil with a relatively large axial length as a main coil, and solenoid coils with small axial lengths as sub-coils arranged at both ends of this coil. By controlling the currents in the main coil and sub-coils, it is possible to form a highly uniform strong magnetic field within the bore at the center of the main coil.

[Problem to be solved by the invention] However, in conventional superconducting coils, the inductance of the subcoil is smaller than that of the main coil, so the magnetic field stability is different when in persistent current mode, and the uniformity decreases over a long period of time. do. Therefore, it is necessary to repeat the current setting relatively frequently, and the current is individually controlled based on an independent power supply, which is a problem in that the operation is troublesome and the configuration is complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide an improved superconducting coil that eliminates the drawbacks of the prior art described above and can form a highly uniform magnetic field with simple operations.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, a threaded cylinder is attached to the main coil so as to be rotatable about the axis of the main coil, and the threads of the cylinder are engaged with each other. A subcoil is installed in each of the cylindrical members, and by rotating the cylinder, the cylindrical member engaged with the screw can adjust the axial relative position of the subcoil with respect to the main coil.

[Example] The superconducting coil of the present invention will be explained with reference to the drawings. In FIG. 1, 1 is the main coil, and 3 and 5 are the main coil 1.
The sub-coils are arranged at the ends of the main coil 1, and are connected in series to the main coil 1, so that they can be attached by a single power source. Reference numerals 2, 4, and 6 are respectively coil winding frames, which are made of, for example, SUS. Inside the winding frame 2, there is a cylinder 20.30 with a ring-shaped ring 21.31 formed on the inner circumference.
are respectively fixed, and the cylinders 20.30 have rotating cylinders 40.50 having screws 41, 51 formed on their outer peripheries, respectively, and projections 42, 52 at the ends thereof are fitted into the grooves 21.31. are rotatably connected.

Moreover, cylindrical members 60.70 screwed into the screws 41.51 of the rotating cylinders 40.50 are fixed to the inside of the winding frames 4 and 6 of the sub-coils, respectively.
0.70, as shown in FIG. 2, splits 61 are formed in the middle of the circumferential direction, and are fitted with the protruding pieces 22 provided on the cylinder 20.30, so that the rotating cylinder 40.50 Even if it rotates, it will not rotate itself.

Such an adjustment mechanism is configured vertically symmetrically so that the upper and lower subcoils 3 and 5 can be displaced in opposite directions, that is, when the upper subcoil 3 is displaced upward, the lower subcoil 5 can be displaced downward. .

The cylinders 20 and 30 and 40 and 50 may be integrated into one body instead of being separated into upper and lower parts.

In the above configuration, the entire structure is immersed in liquid helium, which is a cryogen, so that the fills 1.3 and 5 can become superconducting, and a single power source (not shown) is connected to the main coil l and subcoils 3 and 5. ). After this, the rotating cylinder 40.50 in each adjustment mechanism is attached to its handle 43.
(or 53), if rotated by 'C, cylinder 40.50
As the screws 41 and 51 rotate, the cylindrical members 60 and 70 that engage with the screws 41 and 51 move along the respective protruding pieces 22 due to the anti-rotation mechanism consisting of the split 61 and the protruding pieces 22.

As the cylinder 20, 30 moves, the fixed winding frames 4 and 6 also move in a direction away from the main coil winding frame 2, so that the axial positions of the main coil 1 and the sub-coils 3 and 5 change. Of course, if the cylinders 40 and 50 are rotated in the opposite direction, the moving directions of the subcoils 3 and 5 will also be reversed, allowing them to return to their original positions. Since the central magnetic field of the main coil 1 is constantly measured, when the magnetic field reaches its maximum uniformity, the cylinder 40.5
0 stops rotating, and the main coil winding frame 2 and sub coil winding frame 4
, 6 are fixed.

As is clear from this example, it is possible to obtain a superconducting coil that can form a highly uniform magnetic field with a simplified configuration and simple operations. In particular, since the relative axial position of the main coil and subcoil is adjusted using the alignment of the cylinder and the screw, highly accurate fine adjustment of the coil in the axial direction is possible.

In addition, the illustrated example has a split 61 and a protruding piece 2 as a rotation prevention mechanism.
Although the case according to No. 2 has been shown, this may be an uneven surface or a combination of other unevenness, and the side on which the unevenness is provided may be reversed.

[Effects of the Invention] As explained above, according to the superconducting coil of the present invention, the relative position in the axial direction of the main coil and the sub-coil can be finely adjusted by using the combination of the cylinder and the screw. It has the advantage that it can be connected and energized by a single power source, and a highly uniform magnetic field can be obtained through simple operation.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of a superconducting coil according to the present invention, and FIG. 2 is an explanatory diagram showing the detailed structure. 1: main coil, 2.4 and 6: winding frame, 3 and 5: subcoil, 40 and 50: rotating cylinder, 41 and 51: screw, 60 and 70: cylinder, 61: split, 22: protruding piece. Agent Patent Attorney Susuki 1) Toshiyuki

Claims (1)

[Claims] 1. In a superconducting coil in which a main coil having an axial length of a predetermined length has sub-coils having an axial length shorter than the long axis arranged on both ends of the main coil, a rotating cylinder with a thread is attached to the main coil, and a rotating cylinder with a thread is connected to the axis of the main coil. The cylindrical member is mounted rotatably around the rotating cylinder, and each sub-coil is arranged on a cylindrical member that engages with the screw of the rotating cylinder, and the cylindrical member is locked to the main coil side via a rotation prevention mechanism. A superconducting coil featuring: