Mechanical Structure of 230meV Superconducting Cyclotron to Prevent Harmful Resonance in Lead-out Region

Abstract

The invention relates to a mechanical structure for preventing harmful resonance of an extraction region of a 230MeV superconductive circular accelerator. A magnetic pole of the structure is of a double-layer structure, a lower layer is the root portion of the magnetic pole, an upper layer is a magnetic conducting material shimming plate same as the root portion of the magnetic pole in material, the magnetic conducting material shimming plate is fixed to the surface of the root portion of the magnetic pole of the lower layer, and the protruding side outline of the magnetic conducting material shimming plate of the upper layer has a larger reflection angle compared with the protruding side outline of the root portion of the magnetic pole of the lower layer. Under the condition that the radius of the magnetic pole is not increased, the axial resonant frequency vz in front of an extraction point is reduced, resonance of penetration vz = 1 in front of the extraction point is avoided, axial quality reduction of extraction beam current caused by resonance is prevented, the beam current loss of the extraction region is reduced, and further the irradiation dosage exerted to accelerator maintainer is decreased.

Description

technical field [0001] The invention belongs to cyclotron design technology, in particular to a mechanical structure for preventing harmful resonance in a lead-out region of a 230MeV superconducting cyclotron. Background technique [0002] According to the isochronism principle of the cyclotron, there is [0003] [0004] In the formula, B center is the central magnetic field, c is the speed of light, ω 0 is the particle gyration frequency, r is the gyration radius. Given magnetic field and cyclotron frequency B center , ω 0 , the theoretical isochronous field can be given by formula (1). According to the formula (1), the cyclotron isochronous magnetic field increases with the radius. [0005] The approximate expression of the free oscillation frequency of an isochronous cyclotron is: [0006] [0007] [0008] The degree of modulation F in the formula is determined by the following formula: [0009] [0010] in, =α·B hill +(1-α)·B valley (5) [0...

AI Technical Summary

Problems solved by technology

However, reducing the field drop index n means increasing the radius of the magnetic pole, which will lead to difficulties in the design of the extraction system, and the extraction voltage is too high; the modulation degree F in a small local area changes very slowly and cannot meet the requirements of local reduction

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