Elongated quadrupole ion traps for frequency standard applications

The use of a novel nonaxisymmetric quadrupole ion trap for frequency standard applications is suggested. The properties of such an elongated trap are examined using a cold-ion-cloud model. It is shown that increasing the elongation of the trap, while keeping either the smallest dimension or the volume of the trap constant, substantially increases the ratio of the number of ions that can be stored to the magnitude of the second-order Doppler shift of the ions. This indicates that a frequency standard incorporating an elongated rf ion trap can achieve greater precision than one based on the currently favored circular rf or Paul trap.