It also just becomes difficult to motivate the gas towards the intake of the pump.
IIRC turbomolecular pumps, which are used for deep vacuum applications, have a large intake area and work by basically spinning a huge array of blades at very high speed to bat the individual gas particles out of the working volume into progressively higher pressure areas, ultimately pumped out by a conventional pump.
And then are ion pumps. They have no moving parts at all.
An ion pump (also referred to as a sputter ion pump) is a type of vacuum pump which operates by sputtering a metal getter. Under ideal conditions, ion pumps are capable of reaching pressures as low as 10−11 mbar.[1] An ion pump first ionizes gas within the vessel it is attached to and employs a strong electrical potential, typically 3–7 kV, which accelerates the ions into a solid electrode. Small bits of the electrode are sputtered into the chamber. Gasses are trapped by a combination of chemical reactions with the surface of the highly-reactive sputtered material, and being physically trapped underneath that material.
Will we ever get those structural vacuum balloons that enable more floaty things, like the mites in Neal Stephenson’s “Diamond Age?” Or like the giant floating geodesic ball proposed by buckminster fuller?
I was reading about early Royal Society proposals for flying machines that were based on vacuums in copper balloons. Can any material at any size support a vacuum that can displace the weight of the material? (ie, and thus support lighter than air flight via vacuum)
Those "structural vacuum balloons" are a nice idea but they will have to be made to degrade in sunlight - or else chunks of them will end up cluttering the upper atmosphere, sorta like low-flying space junk.
IIRC turbomolecular pumps, which are used for deep vacuum applications, have a large intake area and work by basically spinning a huge array of blades at very high speed to bat the individual gas particles out of the working volume into progressively higher pressure areas, ultimately pumped out by a conventional pump.