A New Analysis of 4-Rod Radio-Frequency Quadrupole Linac with Intrinsic Field Distortions

概要

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A new formulation for an electric-field potential function in a radio-frequency quadrupole (RFQ) channel with a 4-rod configuration of the electrodes has been developed for analytical study of the effects of the intrinsic field distortion. The RF field in the resonator is expressed as a superposition of four normal modes, coaxial, quadrupole, and two dipole modes, and then the electric-field potential function is expanded into four corresponding components. With this function, an analytical study of beam dynamics for typical RFQ channels with a free-space wavelength (λ) of 2 m has been performed for the case of a periodical accelerating structure. The dependence of beam oscillations on the length of the resonator period l p has been analyzed, including distorted fields. At a long period of the resonator (l p/λ>0.1), resonances of beam oscillations have been found, and their occurrence has been confirmed by numerical simulation. Under the resonance condition with a field distortion of 5%, the beam transmission degrades from 95% to 60%.
INSTITUTE OF PURE AND APPLIED PHYSICSの論文
1997-04-15