alt Hacker NewsThe article pretty much tells you: "Copper's red oxide bonds very well to glass. In fact, the bond is stronger than the bulk glass: when it breaks, there's always a thin layer of glass left stuck to the metal. Along with its excellent electrical properties, it seems like an ideal electrode material." If you look at how vacuum tubes are constructed that's essentially what you see.
Tubes are evacuated through a hole created elsewhere, nowhere near any electrical connections. The getter is then flashed to clean up any gas molecules left over.
Nope, as also mentioned in TFA, copper has a too great thermal expansion coefficient in comparison with glass.
If vacuum tubes had pins of copper, the glass-metal joining would have cracked very soon during normal usage cycles, and there would have been no vacuum left in the tube.
Real vacuum tubes and gas tubes had pins made of kovar, which is a Fe-Ni-Co alloy with a TCE matched to a certain composition of borosilicate glass.
The kovar pins were normally plated with nickel on their external parts, to enable soldering, because molten solder does not wet kovar.