# Questions tagged [cryogenics]

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

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### Why do cryogenic temperatures usually result in higher conductivity, even (sometimes) superconductivity, but otherwise nonconductive Wigner crystals?

Wigner crystals are all the rage in the news, since around the start of the pandemic... But at what temperatures (and pressures?) do these cold materials create a nonconducting 'Wigner crystal' rather ...
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### Work done by gas and it's limits

So I have read about how when pressurised gas does work, it decreases in temperature (turbo expanders, Claude liquefaction etc.). How exactly does that work? The more work a gas does, the more it ...
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### How can you rapidly warm a large body uniformly? [closed]

Given a very non-homogenous large object (mainly water) that's vitrified (cooled down without ice formation) and stored in liquid nitrogen, how do you heat it up to room temperature without ice ...
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### Calculate new equilibrium of cryogenic LNG tank after addition of new cold LNG

Disclaimer: I am not a physicist, but I am trying to unravel this problem and it is interesting me more and more the more I work and think about it. I have the following problem: There is a Cryogenic ...
37 views

### Understanding how the Nernst statement of the Third Law implies the Planck statement

I am reading Callen who, up to and including where I am at (Chapter 11), treats thermodynamics as a classical theory with only the maximum entropy postulate for isolated systems sprinkled in as a &...
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### Linear thermal expansion of a rod at different end temperatures with variable thermal expansion

I am trying to wrap my head around a thought experiment. If I have a thin rod of a uniform material (304SS for example) and hold one end at a relatively high temperature (say 250K) and the other end ...
1 vote
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### Cryostage solid state active insulation

I am designing an ultra-high vacuum cryostage for a fluorescence microscope. The cold finger is cooled by a closed loop liquid nitrogen system. The base of the stage is maintained at room temp with ...
1 vote
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### Labeling system in UHV, cryogenics

So I am currently working with a cryo - fridge with a lot of cables in there. So the goal would be to get some labeling on the cables. An issue with just putting some plastic pieces with numbers in ...
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### Cryogenic and vacuum safe cable labeling or tagging

Not the most in depth of physics questions, yet this feels like the right community for trying to crowd-source this type of expertise. Essentially it is a question for those of you experienced with ...
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### Cryogenic microscope objective

Are the Attocube LT-APO cryogenic objectives with a numerical aperture of 0.82 actually suitable for work with single quantum emitters at liquid helium temperatures? If not, are there any other ...
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### How do we do experiments on gases at zero Kelvin?

We say that at temperatures very close to absolute zero (nano or pico Kelvin) there is no gas, so how do we do experiments on gases at zero Kelvin, and why is Bose-Einstein described as a gas? 1995 – ...
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### Thermogenic transfer of cryogenic gases

Is there any chemicals or substances that can be gases or liquids at around 5 kelvins, and that can also have a high thermal conductivity, at least 3 w/mk
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### Isochoric gas process taking heat from surrounding environment

this is a $pV$-diagram of Stirling cooler: A => B and C => D processes are isothermal, co temperature in D is same as temperature after cooling on high temperature side. Although, temperature ...
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### Which overheating equipment terminated the record-breaking fusion reaction at the JET reactor?

It has been reported in Nature that in December 2021 the Joint European Torus (JET) fusion reactor near Oxford in the UK sustained a 5 second fusion reaction and produced a new record for fusion ...
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### Hydrostatic pressure of helium gas in a closed volume below 4K

I have filled a tight container of a fixed volume with natural helium gas (helium 4) and a sample at room temperature and atmospheric pressure. Now I cool the container down to temperatures between ...
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### How does this author conclude that the volume of the gas is zero at -273.15 degree Celsius?

While reading Gaskell and Laughlin's Intro to ThermoD, I was stuck on something. The relevant passage is: "In 1802, Joseph-Luis Gay-Lussac (1778–1850) observed that the thermal coefficient of ...
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### Superinsulator infinite voltage

Everybody knows about superconductivity, at cryogenic temperatures conductor resistance drops to zero for direct current. There is lesser known related phenomena called superinsulator where material ...
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### How $^3\text{He}$ atoms remove thermal energy from surrounding environment in dilution refrigerator?

I am trying to understand how a dilution refrigerator works. I understand that $^3\text{He}$ atoms are pumped out of the diluted phase and to reestablish an equilibrium, new $^3\text{He}$ move there ...
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### Heisenberg's Uncertainty Principle Applied to Absolute Zero

But absolute zero ($0$ K or $-273.15$ $^\circ$C) is an impossible goal to reach. Practically, the work needed to remove heat from a gas increases the colder you get, and an infinite amount of work ...
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### At absolute zero, how does the gap between the valence band and conduction band increase in silicon crystal?

My book states, " At absolute zero temperature, the electrons are tightly bound by the atoms. At this temperature, the covalent bonds between silicon atoms remain very strong and all the valence ...
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### Can the freezing point of Nitrogen be reduced?

There was an interesting Q/A about mixing helium and nitrogen. Is there anything that can be added to liquid nitrogen to reduce it's freezing point to below 63 kelvin?
1 vote
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### How to measure critical current of a superconducting wire, if my current source can only supply a small current?

I need to determine the critical current of an aluminum wire at 0.1Kelvin. I have access to dilution fridges, but I cannot modify the wiring in the system from room temperature to the sample space. ...
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### Fermi-Dirac statistics and electrical filter

The graph of Fermi-Dirac distribution near absolute zero and an electrical filter looks very similar. My question is does: this similarity finds any application? I can't think of any scenario as such: ...
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### Which volatile ices are hardest below 100 K?

In the context of planetary science, some elements and compounds are informally called volatile instead of refractory, such as H2O, HCN, CO2, NH3, HCHO, CH4, CO, N2. At conditions found near planetary ...
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### Atom flies into deep space. Will it radiate heat and stop eventually?

If an atom flies long enough into deep space, without colliding any other matter or EM waves (purely thoughtful experiment), what does happen? Because velocity vector is unchanged, no EM waves are ...
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### Is the zero-point energy of helium stronger than other liquids to disfavour freezing?

Under normal atmospheric pressures, liquid helium does not freeze even when cooled very close to absolute zero. This is attributed to the uncertainty principle or due to zero-point energy. But the ...
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### What are good books and other resources to study the Cryogenics?

I'm beginner in cryogenics. Also please suggest something which will be useful for study of Electronics at Cryogenic Temperatures.
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### Do good conductors conduct at absolute zero?

The temperature coefficient of good conductors like metal is positive. So with increase in temperature resistance increases and conductance decreases. With decrease in temperature resistance decreases ...
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### Coldest temperatures achievable in DIY enthusiast/hobbyist setting

Assume I, as a physics DIY enthusiast, would like to cool a little piece of material down to coldest possible temperatures, for my own entertainment or my private curiosity/research ambitions. We all ...
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### High pressure cryonics

In this link, it is suggested to use high-pressure cryonics to freeze living cells, tissues or small organism as opposed to various and potentially toxic anti-freeze agent. The core idea is that over ...
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### Why does going close to absolute zero take out friction? [duplicate]

I read in a physics book that when you get close to absolute zero, a liquid stops having friction. Why is that (if it’s even true, that is)?
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### What is the absorption spectrum of liquid nitrogen?

I know that even pure water absorbs some visible light enough to be noticeable over short distances. According to the file File:Absorption spectrum of liquid water.png, the the wavelength of visible ...
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### How does Cosmic microwave background radiation provide temperature to the outer space?

We define temperature as average kinetic energy of atoms. We know that outer space has vacuum that is it lacks matter and hence the temperature should be 0 K. But because of CMB radiation, the ...
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### Expanding universe- Absolute Zero

According to the heat death theory of an expanding universe- entropy decreases. This would mean the temperature approaches absolute zero. But two problems arise: Absolute zero is impossible? Even if ...
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### Do metallic meshes work in practice as thermal radiation shields?

The other day I was thinking about the wire mesh cover used in microwaves to keep the microwave radiation inside cooking your food. The idea is that the spacing of the mesh is much smaller than the ...
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### How do we cool gases to the $mK$ range?

When we set new records for coldest temperature in the universe, we usually do it with gases (see: https://physicsworld.com/a/millikelvin-cooling-of-large-molecules-is-no-myth/) How do we pull this ...
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### Greatest volumetric heat capacity at very low temperatures

There is a theoretical device that I want to keep at a temperature of 3 K using a liquid helium coolant loop, and a block of material as heat sink, initially at 0.1 K. The main limitation is the ...
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### What are the differences between anything at just above absolute zero and something just above the event horizon?

I believe an item that has a half-life would decay at the same rate regardless of temperature (maybe I am wrong on this assumption) but it would definitely slow down due to time dilation above an ...
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### Is it possible to build a "DIY" quantum memory?

I am currently working on a home project which is a computer which will be capable of doing basic quantum computations (my first goal is a random-number generator) based on optical devices. Nowadays I ...
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### How much energy needed to liquify H?

I want to know how much pounds (or the correct measure) would an air compressor need to liquify Hydrogen As its boiling point is somewhat close to -250°C i want to know how to calculate the pressure ...
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### Does the uncertainty principle for energy and time prove it is impossible to reach absolute zero? [duplicate]

I have long wondered why nobody seems to think that this form of the uncertainty principle proves it impossible to reach absolute zero. I noticed that there is a proof suggesting it requires infinite ...
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### How well do magnets work in zero kelvin?

I have read about zero-point energy, this means - alongside Heisenberg's uncertainty principle - that electrons can never be completely motionless. Therefore, since magnet strength is proportional to ...
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### Gas at absolute zero

According to Charles's Law, the volume of gas is proportional to temperate at constant pressure. So, the volume of a gas decreases as temperature decreases. Then, in theory, as the temperature ...
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### Would cooling matter and antimatter to as close to Absolute Zero as possible allow them to coexist?

I was reading about Bose-Einstein condensates and how they affect matter and energy, and I wondered if "draining" that amount of energy from an atom of hydrogen and positronium would potentially allow ...
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### Did NIST fudge this news story about absolute zero?

This press release by NIST, titled "NIST Physicists ‘Squeeze’ Light to Cool Microscopic Drum Below Quantum Limit", makes the following claim: The new technique theoretically could be used to cool ...
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### How did we know that everything had to stop at the absolute zero

The absolute zero is the temperature at which basically even atoms stop moving ( of course I know the enthalpy and entropy version of this but that is not what we are concerned with). Everyone would ...
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### How to achieve temperature below absolute zero?

Firstly i am not a physicist, so kindly go easy on me. So i grew up believing that absolute zero is the bottom of temperature chart. Recently i read that scientist achieved the feat of going below ...
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### Measuring very small temperature differences

Can one use a thermometer with $\pm$5 mK accuracy to measure a temperature difference of 2 mK (the measurement is near 100 mK temperature on a sample on an ADR)? Using the same thermometer, I am ...
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### Should I continue pumping the bolometer overnight?

It's getting late in the lab and I want to head home as fast as I can. The only problem is, that there's a far-infrared bolometer operating at a temperature of 1.8K. This low temperature is attained ...
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