Functional Description
MS Detector
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2-22
______________________ Finnigan LTQ Hardware Manual _______________________
Thus, a cascade of electrons is created that finally results in a measurable
current at the end of the cathode where the electrons are collected by the
anode. The current collected by the anode is proportional to the number of
secondary particles striking the cathode.
Typically, the electron multiplier is set to a gain of about 3
×
10
5
(i.e., for each
ion or electron that enters, 3
×
10
5
electrons exit). The current that leaves the
electron multiplier via the anode is converted to a voltage by the electrometer
circuit and recorded by the data system. Refer to the topic Ion Detection
System Electronic Assemblies on page 2-38.
Figure 2-11. Cross sectional view of the ion detection system, showing
the electron multiplier and the conversion dynode
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