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Looking for information about cryogenics

by subchillin
Tags: cryogenics
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subchillin
#1
Aug9-14, 10:17 AM
P: 4
Hello everybody.
I'm Mike(Subchillin), I'm very new here and terrebly intrested in ALL things Cryo. And I'd like to start by expressing gratitude to the creators of this amazing forum and all the active members, because simply knowing that there is an active online community of people who love physics puts me in a good mood.
I' d like to ask you all for any information you can share about cryogenics in general and cryocoolers particularly.
especially the cryocoolers like in James Webb Space Telescope.

Thank you.
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marcusl
#2
Aug9-14, 10:36 AM
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P: 2,085
Welcome to PF. There is lots of information online. Ball Aerospace built the JWST telescope, including cryocoolers, mirrors and actuators
http://www.ballaerospace.com/page.jsp?page=71
Here's an article on one of their coolers
http://www.google.com/url?sa=t&rct=j...72676100,d.aWw
There's plenty more--just look!
subchillin
#3
Aug10-14, 06:01 PM
P: 4
Thank you.
Good links.
Anymore?

mishima
#4
Aug10-14, 06:41 PM
P: 354
Looking for information about cryogenics

Not sure this would interest you, but you can make a simple cryogenic cooler using dry ice and isopropyl alcohol (95%), both buyable at wal-mart if you are 18+. Dry ice is around 5 dollars for a decent chunk, and the bottle of alcohol is around 2 dollars where I am. It can freeze plant leaves/flowers and you can hit them with a hammer to shatter, if that's your style.

You get 2 buckets/bottles, one which is twice (or so) as big around as the other. Fill the bottom of the big one with dry ice fragments. Poke a few small holes in the bottom of the smaller container, and put the item you are freezing inside. Then put the smaller into the bigger, put more dry ice and fill the space between the 2 containers with alcohol. It takes about 5 minutes to cool down, and the alcohol will form a gel when it is near its lowest temperature.

Obviously you should wear gloves, have good ventilation, and not have any fire sources around. However, my efforts to ignite the alcohol gel did not succeed. I saw did this in imitation of a youtube video but no longer have the link.
Nugatory
#5
Aug10-14, 07:16 PM
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Quote Quote by mishima View Post
my efforts to ignite the alcohol gel....
You do understand that that was a Really Bad Idea(tm), I hope?

But seriously, what temperature does the alcohol and dry ice technique achieve, is it any colder than the dry ice itself, and if so, why?

(Also I have to point out that dry ice dangerous if mishandled, and liquids at cryogenic temperatures are more so. You may know this, but everyone reading this thread will not)
mishima
#6
Aug10-14, 07:35 PM
P: 354
Bad idea: yes. But, I had it under a professional grade fume hood and was wearing full protective gear. Sometimes curiosity can be overwhelming, what can I say.

Dry ice is in theory -78.5 C, and that is the coldest the alcohol could get. The fact that alcohol has a freezing point of even less than this (-110 C) is what makes it work. I did not have sophisticated enough temperature measurement devices to verify this though (as I later found out). As mentioned though, leaves and grapes would harden in around 5 minutes and could be dramatically shattered with a hammer. I suppose its also worth mentioning what did NOT work with this (as opposed to liquid nitrogen), rubber. No shattering racquet balls or even rubber bands unfortunately.

This kind of setup is called a cooling bath in chemistry, and is usually used for reaction vessels of some sort, not ordinary matter (like plants, etc). I still have no idea why the alcohol became a gel. Now that I think about it, I may have asked on this forum and not gotten a response. (edit: I actually did get a response, here is that link, and it also looks like I used 91% alcohol in contrast to my memory: gel talk )
marcusl
#7
Aug11-14, 11:00 AM
Sci Advisor
PF Gold
P: 2,085
Quote Quote by subchillin View Post
Thank you.
Good links.
Anymore?
I found these by Googling "cryocooler" and "james webb space telescope cryocooler." You can do the same thing.

Quote Quote by mishima View Post
Not sure this would interest you, but you can make a simple cryogenic cooler using dry ice and isopropyl alcohol (95%), both buyable at wal-mart if you are 18+. Dry ice is around 5 dollars for a decent chunk, and the bottle of alcohol is around 2 dollars where I am. It can freeze plant leaves/flowers and you can hit them with a hammer to shatter, if that's your style.

You get 2 buckets/bottles, one which is twice (or so) as big around as the other. Fill the bottom of the big one with dry ice fragments. Poke a few small holes in the bottom of the smaller container, and put the item you are freezing inside. Then put the smaller into the bigger, put more dry ice and fill the space between the 2 containers with alcohol. It takes about 5 minutes to cool down, and the alcohol will form a gel when it is near its lowest temperature.

Obviously you should wear gloves, have good ventilation, and not have any fire sources around. However, my efforts to ignite the alcohol gel did not succeed. I saw did this in imitation of a youtube video but no longer have the link.
This is not a cryocooler, which is generally understood to be a closed-cycle device that consumes energy to provide cooling. Look at "cryocooler" in Wikipedia, e.g. A common word for cryocooler is "refrigerator," but colder.

A common word for your device would be "beer cooler," but colder.
subchillin
#8
Aug11-14, 12:41 PM
P: 4
To mishima: Thanks for sharing that, although It's not quite the cryocooler I was thinking about.
I want to be able to build powerful cryocoolers to freeze matter close to 0 K and observe quantom properties of it. May be even come up with an experiment involving superfluidity or other quantom effects of matter near absolute 0.
That is kind of long-term goal. I have to start with ways to get there, which in my opinion is all about cryocoolers.

To:marcusl. Yea I am aware of Google's top search results, but I was hoping for rare, hard-to-find info from people, who deal with cryogenics regularly.
marcusl
#9
Aug11-14, 12:52 PM
Sci Advisor
PF Gold
P: 2,085
Quote Quote by subchillin View Post
I want to be able to build powerful cryocoolers to freeze matter close to 0 K
Cryocoolers probably won't get you "close to 0". They typical reach some few degrees K for work-a-day jobs like operating traditional superconducting magnets (4K), cooling sensors especially in the IR (e.g., James Webb Space Telescope), etc. Lower temps typically require more exotic techniques like dilution refrigerators and paramagnetic salts (both old school), and atomic and molecular laser cooling (all the excitement, and numerous Nobel prizes, over the last 20 years).


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