The Ion Source - Inficon Transpector MPH Operating Manual

The sensor consists of three main parts: (See
 ion source (ionizer)
 quadrupole mass filter
 ion detector
These parts are mounted on an electrical feedthrough flange, bolted to the vacuum
space where the gas analysis measurements are made.
Figure 3-1 Transpector MPH sensor
Ion Source
The sensor works only in a high-vacuum environment because the ions, once
created, must not collide with neutral gas species or the walls of the ion source.
Otherwise, they cannot be detected. At low pressure, the total flight path of the ions
is long enough to pass through the quadrupole without collisions.

3.3 The Ion Source

The ion source of Transpector MPH is optimized for detecting residual gases in a
vacuum system. The sensor has an open construction that facilitates the flow of
gas species into the ionization region.
source in more detail.
Inside the ion source, a large current is put through a filament. This current heats
the filament and causes it to emit electrons, which collide with the gas species
forming ions. Once a gas specie is ionized, electric fields can be used to
manipulate it.
The ions formed in the ion source result from the loss of electrons and thus are
positive in charge.
3 - 2
Quadrupole
Figure 3-2 on page 3-3
Transpector MPH Operating Manual
Figure 3-1.)
Detector
shows the open ion