Multi-pole magnet and harmonic shimming method thereof

Abstract

The invention discloses a multi-pole magnet and a harmonic shimming method thereof. The multi-pole magnet comprises a 2N-pole magnet main body, the 2N-pole magnet main body comprises 2N magnetic pole iron cores, wherein N is an integer more than or equal to two, a pole head area of each magnetic pole iron core is provide with a positioning hole, and the positioning hole is provided with magnetizer hole core in a pluggable way. The harmonic shimming method comprises the following steps of: when each positioning hole formed in the pole head area of each magnetic pole iron core does not have the magnetizer hole core, measuring an initial value of magnetic field harmonic parameter of the multi-pole magnet; if the initial value exceeds a preset allowed error range, determining the positioning hole into which the magnetizer hole core is inserted in the positioning holes according to the difference between the initial value and the preset allowed error range; and inserting the magnetizer hole cores into the determined positioning holes to regulate the current measurement value of the magnetic field harmonic parameter to the allowed error range. The multi-pole magnet and the harmonic shimming method thereof have the advantages of simplicity and high efficiency, and high regulation accuracy can be achieved at low cost.

Description

technical field [0001] The invention relates to the magnetic field measurement technology of a particle accelerator, in particular to a multi-pole magnet and a harmonic shimming method thereof. Background technique [0002] The hexapole magnet is used to correct the chromaticity effect caused by energy dispersion of the beam in the particle accelerator, so as to make the beam more stable. For the design and development of a six-pole magnet, an ideal six-pole magnet requires neither systematic errors nor non-systematic errors (also known as random errors). However, due to the symmetry of the magnet structure, the limited size of the iron core, and errors in the core material, processing, and assembly, there are always errors in the magnetic field of various orders in the actually produced hexapole magnets. Usually, the method of end beveling can be used for harmonic shim to eliminate systematic errors; random errors can be suppressed by improving processing technology and pr...

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Problems solved by technology

[0004] In order to develop this high-precision hexapole magnet, only the method of process improvement can no longer meet the suppression requirements of random errors. For example, the key parts of the magnet, such as the pole surface, need to be processed by high-precision wire cutting technology. The processing accuracy and assembly accuracy of pole head position are required to be less than 0.02mm

However, in the actual magnet production process, it is very difficult to achieve such processing accuracy and assembly accuracy. The produced hexapole magnets generally have other order field errors, especially random errors close to the hexapole field, such as the two-pole field, eight-pole field, etc. The vertical and oblique components of magnetic fields such as polar and decapole fields usually exceed the design requirements, resulting in the accuracy of the hexapole magnets not meeting the application requirements

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