Measurement data fig. 1 To meet the increased demands on vacuum stages, miCos has set up a vacuum test chamber. Equipped with a pumping station (rough pump and turbomolecular pump) the chamber is layed out for UHV down to 10-9mbar - 10-10 mbar which can be reached by pumping and heating the chamber. For HV applications however, it is sufficient to pump down for a period of time which is defined by the rate of desorption of the test stage.
Molecules on the surface of the substrate or chamber (water or hydrocarbon molecules) desorb into a gaseous form and prevent a fast decrease of the chamber pressure. In the graph below the pressure decrease during the desorption process is shown as a function of time, for the chamber itself (lower curve) and for a test stage (upper curve). The dashed lines indicate the fitted 1/T curves.

Measurement data fig. 2 The miCos vacuum chamber is equipped with a fan heater. By heating up the chamber while pumping, the outgasing of products like stages or pushers is highly accelerated. This allows to reach vacuum values of 10-9 mbar and beyond in a reasonable pumping time. The maximal possible outgasing temperature often depends on components like polymere sealings or soft solder. miCos avoids these components in her products whenever possible.
The graph below shows a typical test cycle of pumping down, heating up for outgasing and cooling down to reach the 10-9 mbar range. At several positions at this cycle mass spectra are taken to analyze the residual gas composition.

Measurement data fig. 3 For some applications desorption of a motion stage might be not a problem in general but may depend on the type of outgasing molecules. For example the demand on a stage is to reach 10-6 mbar but hydrocarbon compounds are allowed in a percentage of maximum 1% with respect to all residual gas components. To analyze the outgasing components a quadrupole mass spectrometer is used to perfrom residual gas analysis.
From the resulting mass spectra a conclusion about the present substances may be drawn. In the case shown below water is obviously the main impurity which can be seen on the signal peaks at 17 and 18 atomic mass units.