concerned with temperatures below 123 K (-150 deg C), widespread usage in gas liquefaction and storage, vacuum science and supercondcutivity

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16
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4answers
11k views

How to prolong life of liquid nitrogen in hosehold vacuum flask?

I need to do some work with liquid nitrogen at home. The main question is how to store it without buying huge vacuum flask specifically for liquid nitrogen. I've tried to use usual steel household ...
7
votes
1answer
382 views

Why does the conductivity $\sigma$ decrease with the temperature $T$ in a semi-conductor?

We performed an undergrad experiment where we looked at the resistance $\rho$ and Hall constant $R_\text H$ of a doped InAs semiconductor with the van der Pauw method. Then we cooled it down to around ...
7
votes
1answer
180 views

How are LIGO mirrors cooled?

The recent LIGO announcement Observation of Gravitational Waves from a Binary Black Hole Merger has some technical details about LIGO. For example, LIGO is a modified Michelson interferometer. The ...
5
votes
5answers
408 views

Economical ways for Cooling liquid nitrogen

To have some fun with superconductors I am planning to buy them from here. But it requires me to cool liquid nitrogen to a temperature of 77 degrees Kelvin. Can some one tell me what kind of ...
5
votes
1answer
253 views

How can I make a dry dilution refrigerator quiet?

The pulse tubes are really loud. We've wrapped the helium lines in sound absorbing foam, and we have a cage around the top of the cryostat also lined with foam, but it's still pretty loud. To make ...
4
votes
1answer
197 views

Why 1 Month LHC Magnet Cooling Times

An often quoted figure is that the LHC magnets take a month to completely cool and a month to warm. There is never an explanation as to why that is. I can conjure any number of reasons (slow changes ...
4
votes
3answers
546 views

Can any gas be liquidified by lowering the temperature?

Can any gas be liquidified by lowering the temperature? What happens with gases at absolute zero? Are there gases that remain gases at absolute zero? Do their molecules move at these temperatures? ...
4
votes
1answer
178 views

What is the smallest amount of He you can use to cool a superconducting magnet?

This is an engineering question, but it is adressed to physicists who build accelerators. This question: An electromagnetic space elevator? notices that a NbSn superconducting ring around the equator ...
4
votes
2answers
373 views

From which side should I solder electrical feedthroughs into a vacuum flange?

I work on an experiment that requires electrical connections to a vacuum vessel, which is submerged in liquid helium (LHe). For sending the signals into the vessel, we use a feedthrough flange. I am ...
3
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2answers
965 views

Measuring Cryogenic Temperatures

I need an inexpensive instrument to measure cryogenic temperatures (down to -200C). I can build a thermistor-based thermometer using an Arduino that is accurate to under 1 degree for 0 to 100C. ...
1
vote
1answer
41 views

Cryogenic (LN2) gas vs liquid for cooling

For cooling, would you recommend using gas over liquid or vice-versa? What is the temperature differential between gas and liquid? In other words, at standard volumes and pressures from a gas ...
1
vote
1answer
182 views

Conductive glue

I would like to use some conductive glue to contact a silicon chip's back gate. Any suggestions on what to use? Can I use thermal silver paste? I would be operating at cryogenic temperatures below 4K.
1
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0answers
45 views

Question about Meissner Effect video

In this video, what material is on top of the superconductor disk that keeping it cold? Is it just a circular chunk of dry ice? http://www.youtube.com/watch?v=Ws6AAhTw7RA I'm planning on recreating ...
1
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0answers
79 views

Help wanted achieving cryogenic temperatures [closed]

My son's science project involves liquifying air. I found the Linde process which is the way it was done first. We are trying and not getting very far so I am looking for advice. I have an air ...
1
vote
1answer
625 views

Does a Peltier Thermoelectric layer make a good regulator for LN2 heat-sink interfacing

I understand that when cooling water with LN2 directly (through pipes for example), that it can be too effective, freezing the water (and blocking the pipe). From what I read, regulation of the heat ...
0
votes
4answers
262 views

What happens when I place an object of certain temperature in space ? Does it loose its entire heat energy?

Can i obtain absolute zero temperature this way? And let's assume there is no cosmic microwave background and also assume that there is a way to shield the object from any heat source, such as the ...
0
votes
1answer
317 views

A “bump” in the cooling curve of naphthalene? [closed]

While doing an experiment, I noticed a slight bump in the cooling curve. I have searched for it on the internet and all of the articles say that it is something related to super-cooling. The graph's ...
0
votes
0answers
26 views

Is lossless storage of cryo liquids practically possible due to pressure?

All cryogenic liquid storage tanks I've seen in labs are equipped with pressure relief valves, which will eventually vent all of the liquid when the tank is stored at room temperature. I am wondering ...
0
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1answer
33 views

Cryogenic Conductivity of a Defective Semiconductor

If I have a semiconductor with a lot of defects what happens to its conductivity at at mK type temperatures? I'm expecting that defects would give rise to greater conductivity than for a perfect ...
-1
votes
1answer
32 views

How does a liquefied gas work as a coolant?

What makes liquefied Helium a better coolant than other liquefied gases (like Nitrogen, for example)? Is it because it has a lower boiling point (in which case, will it cool any substance it's in ...