A linear Paul trap without the use of the transverse quadrupole field

A detailed experimental study has been conducted to demonstrate the efficient confinement of ions in the popular four-rod configuration of a linear Paul trap without exciting the transverse radio-frequency (rf) quadrupole field. The three-dimensional (3D) ion confinement is achieved with an identical rf voltage applied to the end electrodes. The optimum operating region is visualized in the stability tune diagram, which indicates that a large number of ions can be stored by adjusting a few fundamental parameters. The lifetime of an ion cloud in the present linear trap is over a second (corresponding to a million rf cycles), long enough for various practical applications. It is also shown through 3D numerical simulations that one can easily extract ions from the trap at a low loss rate below 10%. (author)