Optimizing Performance - HP 5890 Series II Plus Reference Manual

Detector Systems
Thermal conductivity detector (TCD)

Optimizing performance

The following sections aid in choosing operating parameters to obtain
optimal TCD performance.
Temperature
TCD sensitivity increases as the temperature difference between the
detector filament (automatically set) and the surrounding detector body
(chosen detector zone temperature) increases.
To minimize changes in detector sensitivity with different operating
temperatures, filament temperature is maintained at a relatively
constant difference above detector operating temperature. Filament
resistance (proportional to temperature) is monitored, and power is
adjusted as needed to maintain the filament at constant temperature.
Figure 7-9
Filament
Temp
( C)
Filament Temperature versus Detector Block Temperature
146
500
400
300
200
—
T
135 C
100
0
0
100
Detector Temperature (Body
Temp) C
Filament Temperature
Block Temperature
200 30
0
50 C
400