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Temprature

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Electronman

New Member
Hi,

Why they use Boil temperature when they talk about Superconductivity?
For instance they talk about the BOIL temp of helium? Why Boil TEmp??!
 

dougy83

Well-Known Member
boiling is where a liquid turns to a gas. Helium & nitrogen are often cooled until in liquid form to use, in-turn, to cool the superconductor. Superconductivity exists at very low temperatures
 

ericgibbs

Well-Known Member
Most Helpful Member
Sorry but what do you want to tell? I can not understand the reason yet?!

hi,
You have to think in terms of absolute zero, -273Cdeg. 0deg Kelvin.

Relative to this absolute zero, almost every element/compound has a melting and boiling point, where it changes from a solid to liquid to a gas.

Is this what you are asking.?
 

BrownOut

Banned
I think what he means is the boiling temperature of the cooling gas??? Liquid nitrogen is often used, and it has a specific boiling point at a given pressure. The point at which it boils is where it does the best cooling. That's the very same way refrigeration works, although nigrogen in not often used in refrigeration.
 

ericgibbs

Well-Known Member
Most Helpful Member
I think what he means is the boiling temperature of the cooling gas??? Liquid nitrogen is often used, and it has a specific boiling point at a given pressure. The point at which it boils is where it does the best cooling. That's the very same way refrigeration works, although nigrogen in not often used in refrigeration.

hi,
I guess thats we he is asking, specific heat at 'boiling'

Fluids - Latent Heat of Evaporation
 

phalanx

Member
The two most commonly used superconductors are Niobium-Titanium (by a large margin due to price and ease of use) and Niobium-Tin. They have transition temperatures of 10°K and 18°K respectively. At atmospheric pressures, Helium is the only element whose boiling point is lower than the transition temperatures of the superconductors. Helium boils at just over 4°K. The next best element is Hydrogen which boils at around 20°K and is way to high for these superconductors (not to mention it is highly reactive).

The reason why the boil temperature is important is because helium in a gaseous state is a very poor conductor of heat. When helium boils it turns to gas which is ineffective at removing heat from your superconductor. When you are dealing with temperatures that low, even little vibrations can substantially raise temperatures to a point where the superconductor quenches or stops superconducting so it is very important to not boil off your helium.
 
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