Patent ID: 7544934

Claim:
A two-dimensional ion trap mass analyzer, comprising: four elongated electrodes disposed around a device centerline, each of the electrodes having a curved surface oriented toward the centerline; the four electrodes being arranged into first and second electrode pairs, each of the electrode pairs having two electrodes opposed across the centerline; each of the electrodes of the first electrode pair being adapted with a slot permitting the ejection of ions therethrough; a trapping voltage source configured to apply a first oscillatory signal to electrodes of the first electrode pair and a second oscillatory signal to electrodes of the second electrode pair, the first and second oscillatory signals having substantially equal frequencies and magnitudes; and the electrodes of the first electrode pair each having a radius of curvature that is smaller than a radius of curvature of the electrodes of the second electrode pair, the difference in the radii of curvature being selected to substantially reduce non-linear field components arising from the presence of the slots in the first electrode pair.