Methods of operating ion optics for mass spectrometry

In various embodiments, provided are methods for focusing ions for an ion fragmentor, and methods for operating an ion optics assembly. In various embodiments, the present teachings provide methods that substantially maintain the position of the focal point of the an incoming ion beam over a wide range of collision energies, and thereby provide a collimated ion beam for a collision cell over a wide range of energies. In various embodiments, the present teachings provide methods that facilitate decreasing ion transmission losses over a wide range of collision energies.