eli5 Why is a perfect vacuum so hard to create?

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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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Anonymous 0 Comments

Your sputtering machine needs so long to pump down again because it’s likely using a cryo pump, which needs a helium compressor to be constantly pumping. On extended power loss, you need to regen the cryo pump, which takes hours. It’s likely not the actual pumping down that’s taking that long, it’s prepping the cryo pump.

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