Ion Getter Pumps were originally used before the advent of turbo molecular pumps, used in most vacuum applications which require high vacuum pressures of 10-6 mbar. Since turbo molecular pumps became commonplace, ion getter pumps have got even better by way of competition, and have also undergone a series of improvements in order to reach 10-9 mbar. Because of this, ion getter pumps are widely acknowledged by the surface science community as the cleanest and the most efficient way to achieve UHV.
But how do they work? It is well known that an ion getter pump is something which does not have moving parts, and captures and holds gas molecules by converting them into solid compounds. These compounds are then bound in the ion getter pump – allowing the pump to hold a vacuum even when it is not in operation. An ion getter pump is something which works with absolutely no vibration, and is shock-free. An added plus of these is the fact that maintenance is absolutely minimal.
The Assembly of an Ion Getter Pump
In order to achieve and maintain UHV, electron cloud development, gas molecule ionisation, and ion impact is imperative. An ion getter pump consists of one or more elements (which each consist of 2 respective cathode plates and an anode) for pumping. These are both the corresponding external permanent magnets, as well as the housing itself.
The elements themselves are of note in an ion getter pump because they do the actual pumping work. The anodes within them are made up of varying metal cylinders which are welded together in a honeycomb type fashion. At the centre of each cylinder is a penning cell. Essentially, the more cells an anode has, the higher the pumping speed of the element itself. They are located between the two cathodes, and separated from them by a gap of which gas travels through. Electronically, they are insulated via ceramic insulators. The anode and the corresponding cathodes are then connected tightly and then insulated.
The housing then covers the elements- creating a small vacuum chamber which has pockets to hold the pumping elements.
How Do Titanium Sublimation Pumps Work with Ion Getter Pumps?
Not to be confused with the ion getter pump, the titanium sublimation pump is a useful accompaniment. Titanium sublimation pumps tend to have a high speed for pumping some gases, though of course the speed does vary depending on which gas. A titanium sublimation pump works by heating filaments of titanium alloy until the titanium itself sublimates from the surface of this filament into the vacuum which is created.
The titanium then is to precipitate on the surrounding surfaces within the vacuum and forms a thin layer over it. This layer has a high pumping speed when combined with reactive gas, and can be boosted further by cooling the surfaces by introducing water or liquid nitrogen depending on material. Titanium sublimation pumps are strongly recommended for gases such as H20, C0, CO2, and 02. Nitrogen as a coolant is recommended for pumping of H2 and N2.