e-Vision and e-Vision+ LP101013.100 – 01 January 2004
MKS Instruments, Spectra Products
23
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 your analyser and its function
is to take a representative sample of molecules and atoms from your vacuum
chamber, convert them into ions and present them to the quadrupole filter.
2. The quadrupole filter
This is the centre section of your analyser. Its function is to take the ion beam
generated in the source and 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 your 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 your analyser that you will see under normal operating
conditions. Comprising of an industry standard 2.75" Conflat® flange with an
electrical feedthrough, which carries the various supplies and signals to and from
the quadrupole analyser.
All quadrupole analysers require periodic maintenance, the regularity of which is
determined by its 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.
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