A failure mode of standard diode ion pumps pumping argon or other noble gases: argon buried in the cathodes is later sputtered free, producing regular pressure bursts every few minutes. Systems that see process argon, or the roughly 1 percent argon carried in by an air leak, use noble diode pumps, with one tantalum cathode, or triode pumps instead. A sawtooth on the pressure log is the classic signature.
Pressure's sawtoothing every ten minutes, smells like argon instability, is that pump a plain diode?
Also heard as
- argon pumping instability
Related terms
Ion pump
Capture pump that ionizes gas in a high-voltage magnetic discharge and buries the ions in titanium.
Partial pressure
The share of the total pressure contributed by one gas species in a mixture.
RGA
Residual gas analyzer: a small mass spectrometer that identifies which gases remain in a vacuum chamber.
Burp
Brief, sudden pressure burst in a vacuum system from trapped gas, a warming trap or a moving part.