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coillah

Mon Apr 06 2009, 08:10AM

Registered Member #1517 Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304

Anyone here have experience designing them? I am going to spend an entire summer and the better part of next year working on building a nice one for my physics lab and senior project.

I was hoping someone here had some tips on where to start reading.

edit:
While I was waiting for tips, I did a bit more research, and quickly found the AVS, or American Vacuum Society. This led me to their store where I found plenty of reading material. After using their titles for inspiration I went back to amazon and I have found a great multitude of books to read. If anyone would like to make a suggestion, I would appreciate additional input!

Here are some of the books:

Hazmatt_(The Underdog)

Mon Apr 06 2009, 09:05AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

This is also a great book:

It's basically a little encyclopedia of vacuum design and construction for laboratory equipment. It's an older book so it talks more about diffusion pumps then modern turbo or cryo pumps, but its still a cool book.

You will need various things for your system like poppet valves, heavy wall rubber hose, cryo traps, knowledge of brazing stainless steels, and careful planning of your high vac. plumbing for throughput.

If it's a big system, you may even want a tandom roughing stage that switches between two roughing pumps for longevity, but that comes down to cost.

Anyway, hope your system works out, sounds like a cool project. My pump cart probably will never get there due to time limitations.

likewhat

Mon Apr 06 2009, 12:59PM

Account deactivated by user request on 6/11/2009.
Registered Member #1071 Joined: Fri Oct 19 2007, 02:13AM
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Ive built various different systems for different things. What is your application and what type of pressures do you need to get to? I have lots of tips, but most of them are for when it doesnt work and you are trying to find out why. Also, sometimes your experiment changes just slightly and it requires a massive redesign of the vacuum system. Brainstorming about what you could every possibly need in the system is a useful exercise and one that I wish I had done on the last system I built.

coillah

Tue Apr 07 2009, 07:03AM

Registered Member #1517 Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304

Essentially we are trying to build a nice vacuum chamber for surface deposition. This is for our solid state laboratory, my professor has expressed interest in being able to create p-n juntions with the chamber. We have some parts already, the chamber itself I think... But as for the control systems and assembling the chamber, that's my project.

likewhat

Tue Apr 07 2009, 01:37PM

Account deactivated by user request on 6/11/2009.
Registered Member #1071 Joined: Fri Oct 19 2007, 02:13AM
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Are you using conflats for all the flanges? If you require UHV type pressures ( <10^-8 torr) you probably need to bake-out so make sure all your parts can withstand the bake-out temperatures, also make sure you mounted your chamber in a way that lets you bake-out without catching anything on fire. Choosing what feedthroughs you need (if any) to diagnose or make connections to the chamber can be an expensive process if you dont plan carefully. It is wise to consider what gasses you might need to flow into the chamber, and plan appropriately for those connections, you also might need mass flow controllers etc. It is a good idea to draw a picture of it once you get it fleshed out so you can see if anything looks like it might end up being stupid, like feedthroughs that hit each other one they are installed in the chamber. Once you are ready to put it together clean everything and wear gloves to keep from getting oils and stuff in the chamber, one time we had a fingerprint on the inside of a flange and couldnt reach our desired base pressure.

coillah

Thu Apr 09 2009, 01:26AM

Registered Member #1517 Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304

As for the layout of the system, I plan on performing a full CAD mockup of the system before we even consider picking up one part.

I was worried that during assembly we might need a clean room or something, but it sounds like we just need to be extra careful and ensure that our parts are extra clean.

These parts are really nice, I will post some photos of them as soon as I have the time.

I checked out some books from my library and as soon as I have time this semester I want to start diving into them.

rp181

Thu Apr 09 2009, 02:13AM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
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Posts: 1529

Contact some vacuum companies. They will most likley to be happy to talk with you and help you with your design.

likewhat

Thu Apr 09 2009, 04:04AM

Account deactivated by user request on 6/11/2009.
Registered Member #1071 Joined: Fri Oct 19 2007, 02:13AM
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Perhaps I should add. If you need low base pressures (ultrahigh vacuum, 10^-9 torr), it is sort of black magic to get it to work. There are established cleaning techniques involving detergent washing in a ultrasonic cleaner followed by rinsing with deionized water, using lint free towels (kim wipes) and then bagging everything in plastic to prevent any oils from getting on them, it is not that bad once you do 1 part and see how it works. With high vacuum systems your biggest enemy is water, that is why UHV requires a bakeout to drive the water out of the system as quickly as possible. Otherwise the water will slowly come off the inside of the chamber and it will take forever (literally) to get to a low pressure.

Just remember when dealing with UHV just follow the rules to appease the vacuum gods and they will let you get below 10^-8.

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