INFICON 2020ComboPRO Portable Photoionization Detector - Manual (Page 43)

36 ISP-074-575-P1D 36
Figure 3. Photoionization Detector
The ionized molecules in the detector cell are subjected to a continuous electric field
between the repeller electrode and the collector electrode. The ions move in the
electric field, generating a current which is proportional to the concentration of the
ionized molecules in the detector cell. An electrometer circuit converts the current to
a voltage which is then fed to the microprocessor.
The UV lamp is operated by a high voltage lamp driver circuit which delivers high
voltage energy to the lamp through plates in the lamp holder. The lamp driver power
supply is controlled by the microprocessor based on a feedback signal from a light
sensor on the driver circuit board.
Unpacking Instrument
Remove the 2020ComboPRO from its shipping box. The following accessories are
included with the 2020ComboPRO:
1. Sample Probe
2. Instrument Manual CD
3. Multi-Tool
4. AC Adapter or AC Adapter with AC Line Cord
5. Wrist Strap
6. Replacement Sample Inlet Filters (10 pieces)
7. Reference Card
M M
M
M
M
M
e
+
- + + h 
Lamp Power
Supply
Lamp Driver
Circuit
Microprocessor
Light Sensor
Electrometer
+125 Volts
Sample In
Detector Cell
UV Lamp
Lampholder
High Voltage
Plates
Sample Out
UV Lamp
UV Light
Sample
Ionized Molecule
Collector Electrode
Repeller Electrode