7 Analyzer
Ion source
219
Filaments
Two filaments are located on opposite sides of the outside of the ion source. The
active filament carries an adjustable ac emission current. The emission current
heats the filament, causing it to emit electrons; these electrons ionize the sample
molecules. In addition, both filaments have an adjustable dc bias voltage. The
bias voltage determines the energy on the electrons, usually -70 eV.
The filament is shut off automatically if there is a general instrument shutdown.
There are three parameters that affect the filaments: filament selection (
Filament),
filament emission (
Emission) current, and electron energy (EleEnergy).
Filament selection
The filament selection parameter (
Filament) allows you to select which filament in
the ion source is active.
Sometimes, one filament will give better performance than the other. To select the
Entrance lens
Ionization chamber
Lens insulators
Drawout cylinder
Drawout plate
Ion focus lens
Source body
Repeller
Filament
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