Tag Archives: kõrgvaakum

Quadrupole Mass Spectrometer


The quadrupole mass spectrometer (QMS) is used to detect and measure the abundance of gas phase ions. These ions have to pass between electrically connected rods in order to reach the detector. By combining alternating and direct voltage on these rods, it is possible to ensure that only ions with specific mass-to-charge ratio are capable of reaching the detector.



The ‪#‎cryopump‬ is a high vacuum pump that is based on the adsorption of gas on cold surfaces. The cooler the surface – the better the pumping! For that purpose liquid helium is often used for cooling the system parts as it is extremely cold, having a temperature only four degrees above absolute zero. The pumping is done in multiple stages, where each stage has a different temperature. The „warmest“ part is the first stage, that has a temperature of 100 degrees Kelvin (or lower) and that causes water to condensate on it. During the ‪#‎condensation‬ of water also some other gases may also be trapped under the water and that process is called ‪#‎cryotrapping‬. However, in order to effectively pump gases such as nitrogen, even colder surfaces (less than 17 degrees Kelvin) are required. In this stage the metal may also be coated with porous activated charcoal and that allows to adsorb even smaller gas molecules such as helium and even hydrogen (this is called ‪#‎cryosorption‬ ). So basically the pumping of gases with this ‪#‎vacuumpump‬ is based on three processes: condensation, cryotrapping and cryosorption.

Ion Pump


The ion pump is a high vacuum pump that is based on ionizing the gas. When the gas that enters the ‪#‎ionpump‬ it always has some ions in it and those are pulled towards the titanium cathode. These ions are then trapped between the titanium atoms and they may also chemically react with titanium forming solid titanium nitride or titanium oxide, depending on the gas. In addition electrons and titanium atoms are emitted from the cathode when bombarded by the ionized gas molecules. These electrons are then accelerated towards the steel anode as the potential between the anode and cathode is thousands of volts. A magnetic field caused by the magnets makes the electrons move spirally so they spend more time in the open and more likely hit gas molecules to ionize them. The generated gas ions move again towards the cathode and kick out even more electrons and titanium atoms. Some of the kicked out titanium atoms also deposit on the anode and in this process bury gas molecules under them. The pump may work for several years if used in high vacuum environment and if the amount of pumped gas is not large. At some point however the cathodes need to be replaced.