Model 9110T NOx Analyzer

Principles of Operation

PMT Power Supply

&Aux. Signal Connector

PMT Housing End Plate

This is the entry to the PMT Exchange

PMT Output

 

Connector

PMT Preamp PCA

High voltage Power Supply

(HVPS)

 

PMT

 

O-Test LED

 

PMT Cold Block

Insulation Gasket

 

PMT Temperature

Light from Reaction

Chamber shines

Sensor

through hole in side

 

of Cold Block

 

Thermo-Electric Cooler

 

(TEC)

 

PMT Heat Exchange Fins

 

TEC Driver PCA

Cooling Fan

Housing

Figure 13-20: 9110T Sensor Module Assembly

Connector to PMT

Pre Amp PCA

12V Power

Connector

13.5. PHOTO MULTIPLIER TUBE (PMT)

The 9110T uses a photo multiplier tube (PMT) to detect the amount of chemiluminescence created in the Reaction Cell.

A typical PMT is a vacuum tube containing a variety of specially designed electrodes. Photons from the reaction are filtered by an optical high-pass filter, enter the PMT and strike a negatively charged photo cathode causing it to emit electrons. A high voltage potential across these focusing electrodes directs the electrons toward an array of high voltage dynodes.

The dynodes in this electron multiplier array are designed so that each stage multiplies the number of emitted electrons by emitting multiple, new electrons. The greatly increased number of electrons emitted from one end of electron multiplier are collected by a positively charged anode at the other end, which creates a useable current signal. This current signal is amplified by the preamplifier board and then reported to the motherboard.

Teledyne Analytical Instruments

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Image 352
Teledyne instruction manual Photo Multiplier Tube PMT, 20 9110T Sensor Module Assembly