Isochronism magnetic field shimming method of superconducting cyclotron

Abstract

The invention relates to an isochronism magnetic field shimming method of a superconducting cyclotron. A magnetic pole comprises two parts of a bottom magnetic pole and a shimming layer. The shimminglayer is connected and fixed with the bottom magnetic pole by screws, and can be dismounted and taken out from the bottom magnetic pole. A 45-degree oblique angle tapered cutter is used to perform isochronism magnetic field shimming on a chamfer of a side edge of the shimming layer through three-dimensional motion, working depth of the chamfer being changed with radius, and a chamfer depth curve can be obtained through an integral equation method and a least square method. The method can realize magnetic field isochronism shimming in a superconducting cyclotron, prevents a complicated finite element modeling process, and a shimmed magnetic field has good continuity and high precision. A chamfer processing method can reduce local magnetic field saturation of a magnet, reduce the number of coil ampere-turns and fluctuation of the magnetic field with temperature, and improve stability of the cyclotron for long-term operation.

Description

technical field [0001] The invention belongs to the field of accelerator magnet shimming, in particular to a superconducting cyclotron isochronous magnetic field shimming method. Background technique [0002] Isochronism is one of the important indicators to measure the performance of cyclotron. For accelerators with good isochronism, the particle rotation frequency in the accelerator is consistent with the high-frequency frequency, ensuring that the particles are accelerated at the peak voltage every time they pass through the gap of the high-frequency cavity accelerator, and the particles can reach the extraction position after fewer turns, reducing the Beam losses in accelerators. Generally speaking, at the initial stage of cyclotron magnet construction, the magnetic field cannot satisfy isochronism, and the magnetic field needs to be corrected by magnet processing shim. The commonly used magnetic field shimming methods for room temperature magnet cyclotrons are: (1) In...

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Problems solved by technology

Therefore, most superconducting cyclotrons in the world use adjusting coils and adjusting rods to shimming the magnetic field. The shimming amount of the magnetic field is easy to calculate, but the continuity of the shimming magnetic field is poor, and the shimming accuracy is affected. The installation of the rod is relatively complicated, which increases the difficulty of engineering

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