What vacuum calculators would you want?

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
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RobertMendelsohn
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Joined: Mon Jul 20, 2020 4:58 pm
Real name: Robert Mendelsohn

What vacuum calculators would you want?

Post by RobertMendelsohn »

Hello,

I have seen a lot of questions about conductance, pumping speed, and many other vacuum-related calculations. I would be happy to build a (free, ad-free) page of calculators where people could get an answer, with the relevant equation and references to where the equation is found. What things would people find useful?
  • * vacuum conductance of a tube
    * conductance of a thin aperture
    * mean free path, density, temperature
    * velocity distribution
    * leak rate, pumping speed, pressure vs. time
    * unit conversion mmHg/torr/mtorr/hPa etc.
If anyone has any additional ideas, feel free to post it here or DM me. It would be nice to have a single page where there could be (easy/accessible) design tools for those making fusors or other vacuum devices.

Sincerely,

Robert
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Richard Hull
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Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: What vacuum calculators would you want?

Post by Richard Hull »

Many of these calcs are to be found readily in any good book on vacuum technology. This goes back to our often noted "self-directed" learning effort expected here. Research demands reading as well as the doing. With the internet, wandering around research libraries, searching out the correct tomes for information for basics is just not necessary. I found this in a 3 second search

https://www.google.com/search?q=vacuum+ ... e&ie=UTF-8

Note: Such calculations are theoretical under tightly held conditions of the unknowns or initial conditions plugged into those calcs! Do not for one minute believe they represent real world values in any amateur system where slop abounds with zero to nearly worthless instrumentation at hand. Satisfying the values that you plug in the equations as tightly held initial conditions needed to truly predict the results as being accurate are critical, obviously.

Precision and tightly controlled, measured values will yield rather accurate results. Slop, based on bad or non-extant instrumentation resulting in "best guess" initial conditions, and variable operating environments, will yield garbage values not to be found in real world operation.

The best of the books will note this proviso, while others offering up the equations are totally assumptive that your input values are tightly held and precise.

The amateur is rarely able to afford or control the vacuum environment due to zero to near zero quality instrumentation on hand. Many of the questions related to the calculations you seek would be of little value to the average amateur merely "poking about in the dark" on vacuum issues.
95% seen here can't even seal up their systems on first pass!

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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