Experimental study of integer resonance crossing in a nonscaling fixed field alternating gradient accelerator with a Paul ion trap

Abstract

We present an experimental study aimed at exploring integer resonance crossing with a focus on nonscaling fixed field alternating gradient accelerators. The method uses the Simulator of Particle Orbit Dynamics system at Hiroshima University based on a compact ion trap known as a Paul trap. In a setup that mimics the Electron Model for Many Applications nonscaling fixed field alternating gradient accelerator, we have verified the theoretical prediction of the coherent excitation of dipole motion over a wide range of errors and crossing speeds. In addition, the cancellation of amplitude growth dependent on the relative betatron oscillation phase between two consecutive resonances is observed and studied. We also explore nonlinear effects and, in particular, the effects of amplitude-dependent tune shifts and find that these nonlinear effects are a key factor in understanding our experimental results.