A strong magnetic field synchrocyclotron and its magnetic field shim method

A cyclotron and strong magnetic field technology, which is applied in the direction of magnetic resonance accelerators, accelerators, electrical components, etc., can solve the problems of increasing the difficulty of frequency curve matching, so as to improve the matching degree, reduce the beam loss, and reduce the number of shims Effect

Active Publication Date: 2019-12-24
CHINA INSTITUTE OF ATOMIC ENERGY
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  • Description
  • Claims
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Problems solved by technology

The introduction of superconducting technology can greatly increase the magnetic field, thereby reducing the size and cost of the accelerator, but it also increases the difficulty of frequency curve matching

Method used

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  • A strong magnetic field synchrocyclotron and its magnetic field shim method
  • A strong magnetic field synchrocyclotron and its magnetic field shim method
  • A strong magnetic field synchrocyclotron and its magnetic field shim method

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Embodiment approach 1

[0038] A schematic flow chart of the magnetic field shimming method for a strong magnetic field synchrocyclotron provided in an embodiment of the present application is as follows figure 1 As shown, the following steps S1-S9 are included.

[0039] Actual shimming amount acquisition step S1: Acquire the actually required shimming magnetic field amount. In this step S1 , it can be measured by, for example, a four-dimensional motion magnetometer to obtain the actual required amount of shimming magnetic field.

[0040]Shape function construction step S3: Within the radius range that can be processed, the continuous curve is equivalent to a series of rectangular blocks with fixed radial width but height to be obtained, and the shape function of the continuous curve is constructed, wherein the shape function indicates that each rectangular block corresponds to The magnetic field change amount of , the radius range includes multiple radius values ​​r.

[0041] Specifically, in step...

Embodiment approach 2

[0070] Such as Figure 5 As shown, it is a schematic flow chart of the magnetic field shim method provided by another embodiment of the present application, which is similar to the aforementioned embodiment 1, the difference is that there may be certain errors in the linear approximation in step S3, therefore, in this embodiment In the method, an error removal step S8 is also included after the rectangle height calculation step S7 and before the processing step S9. In step S8, the calculation formula involved in step S5 is solved according to the shape function, and the height vector H corresponding to all the rectangular blocks in the rectangular height calculation step S7 is solved to obtain the magnetic field change corresponding to a series of rectangular blocks, and the magnetic field change is obtained The difference with the actual required shimming magnetic field value is used as the newly required shimming magnetic field value and returned to the rectangular height ca...

Embodiment approach 3

[0081] In the aforementioned step S7, sometimes due to ill-conditioned matrix (det(F T For the problem of F)≈0), the solved rectangular block height vector H fluctuates greatly, and the formed curve is difficult to process in engineering practice. Based on this, this embodiment proposes a method to improve the first two embodiments, by artificially increasing the matrix F T The value of the diagonal of F, that is

[0082] H=(F T F+κI) -1 (F T ΔB)

[0083] Among them, I is the unit matrix, and κ is a constant, which needs to be determined after measuring the calculation accuracy and calculating the smoothness of the shimming curve through the weight of experience.

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Abstract

The invention discloses a strong magnetic field synchronous cyclotron and a magnetic field supplementing method thereof, wherein the magnetic pole of an accelerator is of a circumferential structure,and the surface of the magnetic pole is a continuous curve; the method comprises the following steps of acquiring the actually needed magnetic field supplementing amount; in the radius range capable of being processed, enabling the continuous curve to be equivalent to a series of rectangular blocks with the fixed radial width and the height to be solved, and constructing a shape function of the continuous curve, wherein the shape function represents the variation of the magnetic field corresponding to the rectangular blocks; calculating the shape function of the unit height at each radius value position; performing discretization on the actually needed magnetic field supplementing amount, and working out the heights of the rectangular blocks based on the calculated shape function of the unit height at each radius value position and the discretized magnetic field supplementing amount through a function fitting algorithm; and machining the surface of the magnetic pole according to the obtained heights of the rectangular blocks. According to the method, correction of the specified magnetic field amount is realized by adopting a mode of processing the magnetic pole surface curve, the matching degree of the magnetic field and the high-frequency curve is finally improved, and the beam loss is lowered.

Description

technical field [0001] The application relates to the technical field of cyclotron magnet design, in particular to a strong magnetic field synchrocyclotron and a magnetic field shim method thereof. Background technique [0002] The synchrocyclotron uses the principle of stable phase to accelerate particles, and in order to prevent beam loss, the physical design of the accelerator requires that the magnetic field of the synchrocyclotron and the high-frequency frequency curve match. The introduction of superconducting technology can greatly increase the magnetic field, thereby reducing the size and cost of the accelerator, but it also increases the difficulty of frequency curve matching. Higher-precision frequency curve matching requires not only the ingenious design of the high-frequency system, but also the need to change the magnetic field distribution of the accelerator for coordination. Since the inhomogeneity of the magnet material, magnet processing and installation an...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H05H13/00H05H7/04
CPCH05H7/04H05H13/005
Inventor 李明张天爵李鹏展王川
Owner CHINA INSTITUTE OF ATOMIC ENERGY
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