5–9
Transpector CPM Operating Manual
5.2.3.2 The Continuous Dynode Electron Multiplier/Faraday Cup Detector
The Continuous Dynode Electron Multiplier/Faraday Cup (CDEM/FC) detector
amplifies the electron pulse, significantly increasing the analyzer’s sensitivity.
Figure 5-5 CDEM/FC detector
The CDEM/FC detector continuous dynode element is a special type of glass,
rather than a discrete dynode EM which is a copper-beryllium alloy. The advantage
of the CDEM/FC detector over a discrete dynode EM detector is that CDEM/FC
performance does not degrade when exposed to air and does not need to be
stored under vacuum.
The maximum operating temperature for the CDEM/FC detector is 150°C. It can
be baked out at 300°C with the high voltage off.
The CDEM/FC detector is slightly slower to recover after exposure to excessive
input or output currents. It may take a bit longer to stabilize its gain after the high
voltage is changed.
The CDEM/FC detector is operated at high voltages between -0.6 and -2.0 kV.
A new CDEM/FC detector will typically have a gain between 10 and 1,000 at
-0.8 kV. The gain at -3.0 kV typically exceeds 1 x 10
6
. The Transpector CPM
default EM voltage is -0.8 kV.
CDEM Cone
Electron Collector
Signal Output
Deflector Shield
To Next Page
Loading...
Need help?
General