A Beam Slip Phase Measurement Method in Superconducting Cyclotron

Abstract

The present invention provides a beam current slip phase measurement method in a superconducting cyclotron, comprising the following steps: a radial target is fixed at a certain radius of the cyclotron, and the beam current intensity measured on the radial target is measured I b ; Continuously increase the superconducting coil current in smaller steps until the beam current intensity measured on the radial target is 1 / 2 of the original, and record the increase in the superconducting coil current at this time. ΔI 1 . Continue to reduce the superconducting coil current in smaller steps until the beam current intensity measured on the radial target is 1 / 2 of the original, that is, record the increase in the superconducting coil current at this time. ΔI 2 , calculate the central particle slip phase of the beam at this radius position, adjust the radial target to different radius positions, repeat the above steps to obtain a series of central particle slip phases at different radius positions, and evaluate the deviation of the actual accelerator magnetic field from the previous measured magnetic field, The measurement method can accurately evaluate the magnetic field error in the later stage of development, avoid the magnetic field measurement process, thereby greatly reducing the workload and speeding up the development process of the accelerator.

Description

technical field [0001] The invention belongs to the technical field of compact superconducting cyclotrons, in particular to a beam acceleration phase measurement method in compact superconducting cyclotrons. Background technique [0002] Particles rotate in the cyclotron and obtain energy through the same high-frequency acceleration gap multiple times, such as figure 1 shown. The cyclotron magnetic field should satisfy isochronism, that is, the time for particles with different energies to rotate one circle in the magnetic field is consistent with the high-frequency cycle, and the high-frequency accelerating electric field changes with time into a sine wave curve (such as figure 2 shown), which means that when the particle passes through the center line of the high-frequency acceleration gap for the first time, it accelerates at the 90° peak high-frequency phase, and when it rotates once and returns to the high-frequency cavity, it is still at the 90° peak high-frequency p...

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Problems solved by technology

However, due to the large force on the superconducting coil and the poorer mechanical stability than the magnet, it is easy to generate magnetic field errors in the later stage, which will increase the slip phase of the particles.

Therefore, the magnetic field deviation produced in the later stage of the development of the superconducting cyclotron may affect the acceleration efficiency of the beam, and even the beam cannot be extracted due to the large slip phase. However, it is difficult to determine whether the beam cannot be extracted due to a large number of interference items. The relatively large cause is caused by other factors, so it is necessary to re-measure the accelerator magnetic field, dismantle the high-frequency cavity, vacuum and other systems to bring a huge workload, which seriously affects the development cycle

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