Patent ID: 7534998

Claim:
A two-dimensional ion trap mass analyzer, comprising: four elongated electrodes disposed around a device centerline, each of the electrodes having a hyperbolic 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; at least one of the electrodes of the first electrode pair being adapted with a slot permitting the ejection of ions therethrough; and 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, the first oscillatory signal having a magnitude substantially greater than a magnitude of the second electrode pair, the difference in magnitudes between the first and second oscillatory signals being selected to substantially reduce an oscillatory potential at the device centerline.