Collision Cooling of Ions Stored in Quadrupole Radio-Frequency Trap

Abstract
We present a novel model for collisional energy transfer between ions and neutral molecules in the quadrupole radio-frequency trap. Calculated results quantitatively reproduce the dependence of the ion temperature T i on the buffer gas pressure P n, observed on Mg+ ions and several collision partners (H2, He, and CH4). It is deduced from the present model that T i is proportional to P n -1/3 in the low-pressure range below 10-6 Torr, in good agreement with the experimental results.