Unconventional methods for pumping down a vacuum chamber?

[nightsdawnfan]

TL;DR Summary

What are some unconventional or creative methods for rapidly, or even instantaneously, pumping down a vacuum chamber?

Hi all, I'm not sure if this is the correct space so please let me know if it belongs elsewhere. I've always been very interested in engineering. In my spare time, I tend to think about a lot of unconventional ways of doing stuff because I'm of the mindset that there's always new things to discover and I hope someday I can find something truly new!

I've played with the Idea of vacuum airships which are highly improbable to do in this day and age, and for that purpose, I am led to look into the basic principles of how vacuum chambers can sustain a vacuum. So in the spirit of my mindset of unconventionality what are some unconventional or creative methods you might theorize (or know of) for rapidly, or even instantaneously, degassing pumping out all the contents of a vacuum chamber?


Thanks!

 

[phyzguy]

Most of the degassing is water vapor. The hotter you get it, the faster it degasses. Drawing a plasma also helps, because it bombards the walls withe energetic ions that remove gases.

 

[sophiecentaur]

Make that unobtainium perhaps.
Filling containers with substances that make them lighter than their surroundings has worked well for thousands of years. You just need the surrounding fluid to be as dense as water.
There are 'solids' that are lighter than air (this one floats in air / Nitrogen gas, actually) called aerogels. But they are not very strong and could carry no useful payload.
It really is a shame about Hydrogen gas being so buoyant and flammable - a lot better than the next best gas Helium, which is inert. Vacuum is more buoyant than both of them but a vacuum balloon? Hmm.

 

[sophiecentaur]

Most of the degassing is water vapor. The hotter you get it, the faster it degasses. Drawing a plasma also helps, because it bombards the walls withe energetic ions that remove gases.

But do you need such a good vacuum for an airship? Pretty good vacua are very nearly as useful as total vacua so why bother?

 

[phyzguy]

@nightsdawnfan , when people refer to "degassing" a vacuum chamber, they usually mean removing the small quantity of gas that remains after the chamber has been pumped down. Is this what you mean, or do you really mean pumping the chamber down?

 

[nightsdawnfan]

Make that unobtainium perhaps.
Filling containers with substances that make them lighter than their surroundings has worked well for thousands of years. You just need the surrounding fluid to be as dense as water.
There are 'solids' that are lighter than air (this one floats in air / Nitrogen gas, actually) called aerogels. But they are not very strong and could carry no useful payload.
It really is a shame about Hydrogen gas being so buoyant and flammable - a lot better than the next best gas Helium, which is inert. Vacuum is more buoyant than both of them but a vacuum balloon? Hmm.

My thought process for asking this was what if it's possible to rapidly create a vacuum so that you didn't need to focus on sustaining it so much. In effect, there would be a pulsing of suction or buoyancy depending on how rapid you can generate a vacuum and how such a thing is set up to lift a payload.

@nightsdawnfan , when people refer to "degassing" a vacuum chamber, they usually mean removing the small quantity of gas that remains after the chamber has been pumped down. Is this what you mean, or do you really mean pumping the chamber down?

Oh no, thanks for that insight. You are correct, I did mean for pumping the chamber down! Sorry about any confusion. I was also interested in those responses for degassing so they did not go to waste! I have edited my initial message.

 

[DaveE]

I'm not clear on exactly what you are trying to propose. But "lifting a payload" with a vacuum is fundamentally limited by the pressure of the outside world. It is the pressure difference that will provide the force to lift your payload. In space, a vacuum isn't any different than the outside environment, it won't "lift" anything. On Earth at sea level, you can only generate about 15 psi of pressure difference with a vacuum. So, two points here:

1) You really don't need a great vacuum. If you get the vacuum down to 1 psi, you will still have 93% of the ideal pressure difference (14 psi vs 15 psi).

2) You would generate a much greater pressure difference if you used compressed air. A cheap air compressor can easily generate 120 psi. This would give you a pressure difference 7x greater than you can achieve with a perfect vacuum working against the atmospheric pressure of 15 psi.

3) explosives are a way to quickly generate a large pressure difference. This is how guns work.

Finally, a general comment about inventing the next great thing. Whether it's a vacuum source or a payload lifting device. You will spend much less time and effort, and be much more likely to achieve a breakthrough, if you first investigate how the "conventional" methods work; the ones your scheme will be competing with in the marketplace.

 

[Ralph Dratman]

But do you need such a good vacuum for an airship? Pretty good vacua are very nearly as useful as total vacua so why bother?

I do not see how you could pull any kind of vacuum, good or bad, in something light enough to be used as the lifting body of an airship. It is the pressure of the hydrogen or helium in a rigid-body airship that keeps the lifting body from imploding, as it would if the gas were not there.

 

[Vanadium 50]

We get a lot of "vacuum airship" messages. I think at best they are solutions looking for a problem, and at worst hopelessly impractical.

But even if stipulating that this is something we would want to build, the difference between a rough and hard vacuum makes no substantial difference to the lift.

 

[akhmeteli]

I've played with the Idea of vacuum airships which are highly improbable to do in this day and age

According to our calculations, a vacuum balloon can be made using currently available materials. Please see our article https://arxiv.org/abs/1903.05171 and references there.

 

[arydberg]

Making a vacuum is easy. It's finding somthing to put the vacuum in that is difficult. So far most vacuum containing devices weigh thousands of times more than the lifting force obtained.