Patent ID: 7495213

Claim:
A method of operating a linear ion trap having an ion guide, the ion guide having a first end and a second end, the method comprising: a) providing a first group of ions within the ion guide; b) providing a second group of ions within the ion guide, the second group of ions being opposite in polarity to the first group of ions; c) providing an RF drive voltage to the ion guide to radially confine the first group of ions and the second group of ions in the ion guide; d) providing a gas flow of an inert gas in a first axial direction away from the first end of the ion guide and toward a middle of the ion guide to repel both the first group of ions and the second group of ions from the first end of the ion guide; and, e) providing a trapping region barrier for repelling both the first group of ions and the second group of ions away from the second end of the ion guide; wherein the gas flow in the first axial direction and the trapping region barrier together define a main trapping region for trapping both the first group of ions and the second group of ions.