My university has a sputtering machine which is this crazy expensive piece of equipment that has to have a really strong vacuum pump and wacky copper seals and if it loses power for even a minute it has to spend 16 hours pumping it’s vacuum back down.
I know people talk about how a perfect vacuum is like near impossible, but why? We can pressurize things really easily, like air soft co2 canisters or compressed air, which is way above 1 atmosphere in pressure, so why is going below 1 atmosphere so hard? I feel dumb asking this as a senior mechanical engineering student but like I have no clue lol.
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Vacuum is hard, and there will never be a perfect vacuum in a 3d space.
Let’s start:
Have a chamber, with vacuum pumps.
To begin, roughing pumps can remove a lot of the air, but not completely, because at low vac, air is a fluid, and flows.
After Roughing pumps have done their job, you switch in (generic) Roots blowers, to try to feed tge roughing pumps. That might, with perfect roots blowers, get you down to 10 to the -3 Torr.
For big chambers, now you need a vacuum booster, which is basically a big cone, surrounded with cooling pipes, to coerce random air molecules to get a bit heavier, acd be able to let the Roots Blowers suck out.
Now we are at the level of literal molecules, not attached to one another, so pumping can’t happen.
At this point, you open up HUGE ports, into your Vacuum vessel, and spray through almost a Christmas tree, extremely low vapor pressure oil, that captures floating molecules of any gas, concentrates them at the bottom of the diffusion pump, and uses roots blowers/roughing pumps to get those few molecules out.
But not every air molecule, or even singular element, will drift into the diffusion pump in a reasonable time. Now we are at 10 to -6/7 torr.
There are still individual atoms/molecules floating randomly around. They don’t flow with any other, and we can’t cool them to make them sink. So there is not a perfect vacuum.
Even if I could create a perfect (and I mean PERFECT) Vacuum, quantum particles would randomly appear/disappear.
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