This UHV magnetron sputtering system developed a major leak after a bake-out.
The leak found in this video is tiny. The huge main leak is still to be found.
This small leak however confirms that the leak detection mode of the Residual Gas Analyzer works, which we were not completely sure of before.

The turbo-molecular pump is a Varian TV 1001 Navigator. It is backed by an Edwards nXDS10i Scroll Pump.
The MKS Vacscan Plus RGA can detect the composition of the gases inside the chamber or can be used as a leak detector looking only for helium (making this highly useful annoying noise to indicate the helium level).

In this case we have a perfect ratio of atmospheric gases inside the chamber and the base pressure with the leaks is 1.5*10^-7torr.
If not leaking, it would normally get down to the 10^-10 torr-range.

The helium flow in this video is a bit high for leak-checking, but i could not set the regulator on a stable pressure lower than this.
Normally a helium flow of about 2-3 bubbles per second in water would be adequate.

People commonly use way too much helium when leak checking, increasing the helium background in the room and making small leaks impossible to detect.

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