
2.2 BGC-FTIR-Container - Monitoring
It is not only important to provide all the meteorological data, you also have to bear
in mind the conditions inside the BGC-FTIR-Container. In oder to do this several
sensors are mounted for monitoring the crucial parameters in case of a failure in air
conditioning or simply to control temperature inside the FTIR instrument.
2.2.1 Temperature Probe - Campbell Scientific T107
Function
A low pressure gas cell filled with HCL is used to provide narrow absorption lines
at a number of different frequencies across the bandwidth of the FTIR instrument.
The gas cell acts as an internal calibration reference and is placed directly into the
solar beam. Campbell Scientific‘s Temperature Probe T107 is shown in Fig. 2.14.
It is used for monitoring the temperature inside the FTIR spectrometer next to the
gas cell because absorption lines depend on temperature. Two redundant sensors
are used for monitor the temperature of the gas cell.
Figure 2.14: Temperature Probe T107
[Manual - Model 107 Temperature Probe, 4/07]
Measuring Principle
The Temperature Probe T107 uses a thermistor to measure temperature. This
thermistor is a kind of resistor with resistance varying according to its temperature.
The sensor measures the voltage drop across the 1K ohm resistor according to Fig.
2.15.
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