Dependence of Temperature of Collision-Cooled Ions Stored in an RF Trap on Trapping Parameters

The kinetic property of ions stored in an RF-quadrupole trap is investigated theoretically and experimentally. We observed the dependence of the temperature of the ions on the trapping parameter (q z) and the number of ions in the presence of He buffer gas. The results are well explained by a model which represents the collisional energy transfer between ions and neutral molecules assuming a kinematic collision between them.