Ion Pump Element Styles
CV Element (solid titanium cathodes)
Ions impact a titanium cathode directly or at a slight angle. Reactive gases chemically react with the titanium and can either lodge in the cathode or reflect onto the anode as high-energy neutrals, where they then remain.
Advantages: high reactive gas pumping, optimal pressure indication, superior electrical stability, superior vacuum stability
Disadvantages: low noble gas capacity, lower starting pressures, potential Ar instability
DI Element (solid titanium/tantalum cathodes)
In addition to reactive gas pumping using titanium, noble gas ions that hit the tantalum cathode are reflected back toward the anode structure. There they are permanently deposited in the non-sputtered areas and covered by fresh sputtered material.
Advantages: noble gas pumping, optimal pressure indication, electrical/vacuum stability, 80% of CV reactive gas pumping
Disadvantages: lower starting pressures, high material cost
TR Element (slotted titanium cathodes)
Ions glance off the cathode, physically and chemically reacting with the titanium cathode materials. The glancing action directs most sputtered materials toward the vacuum chamber wall of the ion pump.
Advantages: higher starting pressures, noble gas pumping, tantalum not required, 75% of CV reactive gas pumping
Disadvantages: Lower UHV pumping speeds, high manufacturing costs, electrically unstable (arcing), vacuum instability (arcing)