Biomedical Engineering Reference
In-Depth Information
Fig. 6
Simulated potential of the ionization chamber and ion extraction
Fig. 7
Ion extraction and
focus optic
is to extract and generate a concentrated parallel ion beam of defined energy.
Accordingly, the first pair of electrodes (IE) extracts and accelerates the ions (see
above), whereas the second pair (IFO) decelerates and thereby focuses them [
21
] .
The design is similar to conventional mass spectrometers [
22
] .
Figure
7
shows the structures of the ion optics with the ionization chamber on the
left and the entrance of the mass-analyzer on the right, which are described in the
next section. The arrangement and shape of these structures were also computed via
ion trajectory simulations. A result is shown in Fig.
8
. At an extraction voltage (IE)
of −25 V and separator input voltage (WFP) of 0 V an ion focus voltage (IFO) of
67 V generates the highest ion yield for the separator.
