Experimental Demonstration of Nonlinear Resonances in a Linear Paul Trap

A variety of resonances have been observed experimentally in a linear Paul trap. They are excited by weak nonlinear fields that exist within the trap aperture depending on the mechanical design and misalignments of the electrodes. Those inevitable nonlinear terms in the ion confinement potential couple the axial and transverse degrees of freedom, making the resonance feature quite complicated. High-order resonances are weak as expected, unless driven by strong error fields or the space-charge potential. Systematic numerical simulations are performed to confirm the origin of each resonance line experimentally identified in the tune diagram. The numerical data suggests that a large fraction of the ions getting unstable and lost due to high-order resonances belong initially to the tail of the Gaussian-like ion distribution in phase space, namely, the lost particles have relatively large oscillation energies from the beginning.

Automated summary

Various resonances have been experimentally observed in a linear Paul trap, excited by weak nonlinear fields. High-order resonances are typically weak, unless driven by strong error fields or space-charge potential. Numerical simulations confirm the origin of each resonance line and show that most ions lost due to high-order resonances have relatively large oscillation energies from the beginning.