Method of optimizing geometric and electrostatic parameters of an electrostatic linear ion trap (ELIT)

An electrostatic linear ion trap (ELIT), comprising:

• first and second ion mirrors,
• an electric field free region including a charge detection cylinder positioned between the first and second ion mirrors, the first and second ion mirrors, the field free region and the charge detection cylinder axially aligned with one another along a central, longitudinal axis, the first and second ion mirrors each including a plurality of axially spaced apart electrodes, and
• at least one voltage source configured to supply voltages to each of the plurality of electrodes of the first and second ion mirrors to establish electric fields in each of the first and second ion mirrors to trap an ion in the ELIT such that the ion oscillates back and forth between the first and second ion mirrors each time passing through the charge detection cylinder and such that a mass-to-charge ratio (m/z) of the ion depends on a frequency of oscillation of the ion within the ELIT,
• wherein the voltages supplied to the plurality of electrodes of the first and second ion mirrors are selected such that the m/z of the ion is independent of a trajectory of the ion entering into and oscillating within the ELIT,
• and wherein a length of the electric field free region is selected such that the m/z of the ion is independent of an energy of the ion entering into and moving within the ELIT.