For 0.1 atmosphere, RTV around a wire is more than sufficient. The vacuum
side is only 14.7PSI and that really isn't much pressure trying to get in.
The reason for the glass seals and so forth is that when you are down at
nano torr values, the inflow is sufficient to drop that vacuum level real
fast. At 0.1 of air pressure, the inflow is so small that it will take
years to do significant damage to the vacuum. Remember that a steel (not
even a polished steel but just run of the mill steel surface) to rubber
interface holds air in a tire for many years in an automobile tire.

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Why do penguins walk so far to get to their nesting grounds?