The internal end 15i of the inlet device 15 can be between about 1-50 mm from the front of the mass analyzer 30, e.g., the front endcap of the ion trap. In some embodiments, the internal end of the inlet device 15i can reside between about 1-10 mm or between about 1-5 mm from the front of the mass analyzer 30.
Although shown with the accelerating and gate electrode configurations in FIGS. 1 and 2 and with the focusing electrode 48 as a tube electrode 48t in FIGS. 3A and 4A, other focusing/lens electrode arrangements can be used. The discharge end of the inlet tube 15i can extend a distance into the focusing lenses and/or electrodes. For example, the focusing electrode 48 can comprise an Einzel lens and/or ion funnel 48f. FIGS. 3C and 4C illustrate that the mass spectrometer 10 can have a focusing electrode 48 that comprises an ion funnel electrode 48f upstream of the mass analyzer 30 in the vacuum chamber 12 holding the mass analyzer 30.
An accelerating electrode, such as electrode 28 (FIG. 1) is typically electrically connected to the capillary inlet tube 15 and/or capillary ESI device 20t, and the field generated accelerates ions toward the mass analyzer 30, e.g., ion trap. The “focusing electrodes” discussed above focus the ions (which may have been accelerated by the “accelerating electrode”) into the mass analyzer 30, e.g., ion trap. Thus, the mass spectrometer 10 can include a variety of different ion optic (focusing or “l(fā)ens” electrode configurations).
