Figure 14. Velos Pro Exit Lens And S-Lens (Back View) - Thermo Scientific LTQ Series Hardware Manual

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Functional Description
Mass Spectrometer
Ions from the ion transfer tube enter the S-lens. Rf is applied to the S-lens to focus the ions
toward the opening of the exit lens. When you tune the Velos Pro mass spectrometer, adjust
the S-lens rf to maximize sensitivity.
The Velos Pro uses an S-lens and exit lens rather than a tube lens and skimmer. The exit lens
acts as a vacuum baffle between the higher pressure ion source interface region and the lower
pressure MP00 rf lens region of the vacuum manifold. The S-lens is an ion transmission
device consisting of progressively spaced, stainless steel electrodes (Figure 14). An rf voltage is
applied to the electrodes, and adjacent electrodes have voltages of opposite phase. As the rf
amplitude increases, ions of progressively higher mass-to-charge ratios pass through to the exit
lens and move toward the MP00 rf lens. During the tune procedure, the Velos Pro determines
the mass-dependent rf amplitudes for optimum transmission of ions through the lens.

Figure 14. Velos Pro exit lens and S-lens (back view)

Exit lens
S-lens
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