# Tag Info

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Try a styrofoam cooler: They're about $5 at Walmart. Your homemade dewars should fit easily inside and should be reasonably sealed from atmosphere. We used to use this in my Senior Lab in undergrad to freeze samples overnight, there was always plenty left in the morning, so I imagine that the combination should get you near that 3 day mark. 7 As an "infrared survey technician" part of my job was keeping our infrared camera topped off with liquid nitrogen. We had a large dewar (about the size of a barrel) at the shop that was filled bi-weekly. For daily excursions we used a smaller dewar (about the size of a pony keg). Both of these dewars were specifically designed to contain cryogenic liquids, ... 6 There is at least one tutorial on the web that illustrates a means by which one can build a device to condense one's own nitrogen. I haven't tried to duplicate this setup, but the principles seem sound. It essentially uses regenerative cooling by exploiting the fact that gasses cool when the pressure is suddenly lowered (via the Joule-Thomson effect). Be ... 5 This should be a comment as I'm not knowledgeable about the LHC refrigeration, but it's too long for a comment and I can hazard a pretty good guess. Sheer heat capacity likely accounts for a great deal of this time. Assuming the total amount of kit that needs to be cooled is, say$2\times10^4$tonnes, and if it has roughly a$1{\rm kJ K^{-1} kg^{-1}}$heat ... 4 Just spit-balling as I have never tried this. Use the best dewar(s) you can find. Silvered glass walls and a vacuum gap. Assuming you can take as much LN2 as you want, use the biggest dewar(s) you can find. Not only is there more there, but the surface area to volume ratio works in your favor. Keep the dewar(s) in a cool, enclosed place. You'd like them to ... 4 If (hypothetically) you could find a far off region of space where there is no radiation of any sort, and you place a hot object there, then it would radiate away its heat and gain no heat back from its surroundings. The rate of radiation would gradually decrease but eventually it would lose its last photon and enter a ground state of absolute zero ... 3 This answer is only an order of magnitude estimation. The main uncertainty comes from the fact that for a constant current the cooling power is not determined by the superconducting wire but from the quality of the isolation against radiation, convection and conduction of warmer parts of the structure to the cold wire at 4.2K We can use the LHC ring as an ... 3 Phonon scattering goes up a lot as temperature increases -- faster than electron numbers increase in the conduction band. Keep in mind that phonons obey the Bose-Einstein distribution, so their numbers scale like $$N_{BE}=\frac{1}{e^{\frac{\hbar\omega}{k_b T}}-1}$$ In the large$T$limit, this becomes $$\frac{k_b T}{\hbar\omega}$$ So their numbers ... 2 You ether can take usual K-type thermocouple (like in multimeters), and calibrate it - it supposed to work fine in LN2. I personally tried that with DMM and it worked (though showed large error). Multimeters use simplified conversion formulas and could give huge errors at cryogenic temperatures - so remember that you ether need table-based conversion, or ... 2 If this case is still open, here are a couple of options. Both PRT-100 and thermocouples are feasible solutions. If using a thermocouple, E type has the highest sensitivity at cryogenic temperatures (even down till 40 K, LN2 is 77 K as you know). However as pointed out above, thermocouples generate very low voltage and this output signal is prone to EM ... 2 You can buy liquid nitrogen, it generally costs a$1/litre but as you need a fairly large refrigerated tanker truck to deliver it in - they tend not to sell small amounts. A local hospital/university lab would probably be happy to let you have a litre, it's easily carried in a thermos flask, unless you live in a country heavily infested with lawyers. edit: ...

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There's a fairly cheap tutorial from instructables: Homemade Liquid Nitrogen Generator (Instructables)

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In general you don't condense your own nitrogen in small amounts. If you have an industrial-scale refrigeration plant you can profitably sell already-liquid nitrogen for about the same price per liter as milk. If you drive around town looking at the loading docks behind university buildings, hospitals, maybe machine shops, you'll see a little fenced area ...

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I'm afraid we've found no real solution to this problem. I think the noise propagates through the support frame, and sound proofing doesn't help very much. I think your best bet is either noise cancelling headphones or remote desktop as much as possible. But neither solution will help other people who may be in the same lab.

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Any object that approximates a black body (which means pretty much everything) radiates heat according to the Stefan-Boltzmann law: $$W = \sigma T^4$$ If we could insulate the object from all incoming radiation (which is impossible, but let's go with it for the sake of this question) the change of temperature with time would be given by:  C ...

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There are, of course, 3 mechanisms for heat transfer - conduction, convection and radiation. So isolated in vacuum convection and conduction will play no role (provided, of course, the vacuum is perfect, which is a pretty good assumption for space, but not quite reality). I am guessing from your question that no radiation hits the object in your thought ...

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Carbon dioxide at standard atmospheric pressure does not liquify as it is cooled. It directly desublimates from gas to solid. Phase changes are typically associated with a large inflow or outflow of heat. We are usually familiar that heat has to be put into ice to melt it, heat has to be put into a pot of water to boil it. This motion of energy is ...

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Call your local welding supply store. They generally have some. If you live in a small enough town and they want to deal with you, they'll be happy to sell you some. Be up front, tell them what you intend to use it for and how you're going to handle it. If you're using it for school or science fair, this typically paves the way. It will evaporate fairly ...

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As we decrease the temperature, the vibration decreases and decreases until, at absolute zero, there is a minimum amount of vibration that the atoms can have, but not zero. This minimum amount of motion that atoms can have is not enough to melt a substance, with one exception: helium. Helium merely decreases the atomic motions as much as it can, but even at ...

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A Bose-Einstein condensate can made by cooling a (very) dilute gas, and once the condensate has formed it can be cooled arbitrarily close to absolute zero without forming a liquid or a solid phase. The atom energies approach zero, but the atoms don't crystallise because they become delocalised instead.

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Your chamber's thermal cycling environment is indeed "very demanding". You have my sympathy... From O'Hanlon's A User's Guide to Vacuum Technology, Chapter 17, Joints, Seals and Components: Welds: It is important to make the weld on the surface which will be exposed to vacuum. If the weld is made on the atmospheric surface, a gap may be created which ...

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I have used silver conductive paint for quick tests of superconductors in a helium cryostat, and it worked fine. Will it also be a vacuum? I've seen others use a blob of indium solder for electrical connections as well.

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