MKS HPQ3, Hardware Manual

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MKS Instruments UK Ltd
HPQ3 Hardware Manual – SP101019.101 October 2012
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7. Analyser Maintenance
7.1 Overview
The quadrupole analyser is the front end of your mass-spectrometer, it produces electrical signals
which, when presented to your electronics display the contents of your vacuum chamber in a
meaningful fashion.
The analyser can be broken down into four separate areas by virtue of their function.
1. The ion source or ioniser
This is located at the top (furthest from the flange) of the analyser and its function is to take a
representative sample of molecules and atoms from the vacuum chamber, convert them into ions
and present them to the quadrupole filter.
2. The quadrupole filter
This is the centre section of the analyser. Its function is to take the ion beam generated in the
source, separate the various ions by their mass to charge ratio (m/e) and present the single
selected m/e to the collector.
3. The detector
This area of the quadrupole analyser is "hidden" inside the flanged housing. Its function is simply to
convert the filtered ion beam presented by the quadrupole filter into a small electrical current,
which can be passed to the electronics for amplification and subsequent display to the outside
world.
4. The flanged housing
This is the only part of the analyser seen under normal operating conditions. Comprising of an
industry standard 2.75" Conflat® flange with an electrical feedthrough carrying the various supplies
and signals to and from the quadrupole analyser.
All quadrupole analysers require periodic maintenance, the regularity of which is determined by
their use. The cleanliness of the vacuum, hours of operation and the type of sample being
analysed all have an effect on the analyser’s performance.
Apart from these considerations there are times when the analyser will require maintenance and
these are when accidents happen i.e. the vacuum is vented with the filaments on, or someone
forgets to turn on the water cooling for the oil diffusion pump.