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Analyzer
7
Ion source
Ion source
The ion source operates by electron ionization (EI). The sample enters the ion
source from the GC/MSD interface. Electrons emitted by a filament enter the ion-
ization chamber, guided by a magnetic field. The high-energy electrons interact
with the sample molecules, ionizing and fragmenting them. The positive voltage
on the repeller pushes the positive ions into the lens stack, where they pass
through several electrostatic lenses. These lenses concentrate the ions into a tight
beam, which is directed into the mass filter.
Ion source body
The ion source body is a cylinder. Its cylindrical geometry ensures proper align-
ment of the lens stack. It holds the other parts of the ion source. With the repeller
and the drawout plate, it forms the ionization chamber. The ionization chamber is
the space where the ions are formed. Slots in the source body help the vacuum
system to pump away carrier gas and un-ionized sample molecules or fragments.
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