Titanium Sublimation Pump - Common Misconceptions

Common Misconceptions

Although there are titanium based ion pumps, it is possible to falsely infer that the operation of these pumps is related. This has perhaps also fueled the misconception that a TSP operates in gas phase, i.e. the titanium atoms or clusters from the source collide with molecules from the residual gas, and form gaseous products which are heavier and therefore easier for ion-pumps and turbomolecular pumps to remove. Although this sounds plausible, TSPs are most effective when the residual gas pressure is sufficiently low for the gas to behave ballistically (i.e. the mean free path in the gas is large and thus the probability of collisions within the gas is insignificant compared to the probability or collision with the chamber walls).