Thermo Finnigan LTQ - Vacuum System and Inlet Gasses Hardware

Functional Description
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_______________________ Finnigan LTQ Hardware Manual _____________________
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The ion detection system of the LTQ increases signal and decreases noise. The
high voltage applied to the conversion dynode results in a high conversion
efficiency and increased signal. That is, for each ion striking the conversion
dynode, many secondary particles are produced. The increase in conversion
efficiency is more pronounced for more massive ions than for less massive
ions.
Because of the off-axis orientation of the ion detection system relative to the
mass analyzer, neutral molecules from the mass analyzer tend not to strike the
conversion dynode or electron multiplier. As a result, the noise from neutral
molecules is reduced.
Vacuum System and Inlet Gasses Hardware
The vacuum system evacuates the region around the API stack, ion optics,
mass analyzer, and ion detection system. The principal components of the
vacuum system include the following (see Figure 2-12):
• Vacuum manifold
• Turbomolecular pump
• Forepump
• Convectron
®
gauge
• Ion gauge