Electrical conductivity of liquid argon

[doctor_cat]

Dear friends,

does anyone know if there exists any study about electrical conductivity of liquid argon?

Thank you in advance for any suggestion.

 

[berkeman]

Welcome to the PF.

I Googled your thread title, and got lots of good hits. Have you read through them already?

https://www.google.com/search?q=Ele...uid+argon+&ie=utf-8&oe=utf-8&client=firefox-b

 

[doctor_cat]

Sorry, I forgot to specify I am interested in liquid argon at low pressure (maximum 3atm).

On Google, I found only studies about overpressured liquid argon (tens of MPa).

 

[Tom.G]

Take a look at this site: https://lar.bnl.gov/properties/
You may have to find someone to translate electron mobility, drift velocities, and diffusion coefficients to something more usable to us civilians!

Above found with: https://www.google.com/search?&q=Electrical+conductivity+of+liquid+argon+at+low+pressure

 

[doctor_cat]

Take a look at this site: https://lar.bnl.gov/properties/
You may have to find someone to translate electron mobility, drift velocities, and diffusion coefficients to something more usable to us civilians!

Above found with: https://www.google.com/search?&q=Electrical+conductivity+of+liquid+argon+at+low+pressure

Thanks.

Perhaps, someone in this forum is able to derive electrical conductivity from electron mobility, drift velocity, etc.

 

[phyzguy]

What exactly is your motivation or the application that prompts your question? I think liquid argon is, for all practical purpose, an insulator. It is used in particle physics experiments to detect high-energy particles. When a high energy particle makes a collision in the liquid argon, it creates free carriers which can be swept up and counted by a counter. So the stats on electron mobility, etc., refers to that application.

 

[kimbyd]

Electrical conductivity is related to the Electron Mobility:
https://en.wikipedia.org/wiki/Electron_mobility#Relation_to_conductivity

However, this contains an important variable: the electron density. This density is not the total density of electrons in the substance, but rather the density of "free" electrons. Neutral, low-temperature/pressure Argon will not have any free electrons.

That said, I did find this source, which measured the electrical conductivity of Argon, Krypton, and Xenon at high pressures (and presumably temperatures):
https://aip.scitation.org/doi/abs/10.1063/1.1303633

They do find some conductivity, but it's not a simple relation: the conductivity depends exponentially upon temperature within certain experimental regimes (this is expected for substances with no free electrons). I can't access the full paper, so I don't know the details.

My guess is that the answer is that the conductivity is zero at low temperatures, but it's possible for Argon to become conductive at high pressures and temperatures.

 

[doctor_cat]

What exactly is your motivation or the application that prompts your question? I think liquid argon is, for all practical purpose, an insulator. It is used in particle physics experiments to detect high-energy particles. When a high energy particle makes a collision in the liquid argon, it creates free carriers which can be swept up and counted by a counter. So the stats on electron mobility, etc., refers to that application.

The aim is to study the propagation of RF waves in liquid argon detectors.

 

[kimbyd]

The aim is to study the propagation of RF waves in liquid argon detectors.

This might be useful:
https://arxiv.org/abs/1511.07724

Edit, just noticed the RF wave point:
I'm not sure the conductivity will be the most important factor in determining the attenuation of RF waves. The paper I linked above shows an experiment where they were testing for much higher-frequency signals (for the purpose of understanding how Cherenkov radiation travels through liquid argon), but as the attenuation drops off pretty sharply at lower frequencies in their test, my bet is that the attenuation will be effectively zero for RF waves.

Attenuation of RF waves in liquid Ar, if it is significant at any frequency, would likely be driven by complicated quantum effects (such as particular frequencies exciting certain resonant modes in the Ar fluid).

 

[doctor_cat]

Electrical conductivity is related to the Electron Mobility:
https://en.wikipedia.org/wiki/Electron_mobility#Relation_to_conductivity

However, this contains an important variable: the electron density. This density is not the total density of electrons in the substance, but rather the density of "free" electrons. Neutral, low-temperature/pressure Argon will not have any free electrons.

That said, I did find this source, which measured the electrical conductivity of Argon, Krypton, and Xenon at high pressures (and presumably temperatures):
https://aip.scitation.org/doi/abs/10.1063/1.1303633

They do find some conductivity, but it's not a simple relation: the conductivity depends exponentially upon temperature within certain experimental regimes (this is expected for substances with no free electrons). I can't access the full paper, so I don't know the details.

My guess is that the answer is that the conductivity is zero at low temperatures, but it's possible for Argon to become conductive at high pressures and temperatures.

It should be like you guessed.
I will try to have access to the paper.

 

[f95toli]

I think one issue is being overlooked here.

If the question is about real liquid argon I am pretty sure the RF properties (e.g. loss tangent) will be dominated not by the argon itself (which is presumably a very good insulator) but by the presence of various impurities.
This is certainly the case for most low-loss crystals such as sapphire (crystalline aluminium oxide) which "in theory" has loss tangent of something like 1e-11; but in reality you would be very lucky to find a real sample with a loss tangent lower than high 1e-7 (at low temperatures); the difference is simply due to presence of very low concentrations of various impurities (in sapphire ions.such as e.g. chromium and iron).
Granted, the effect of impurities will be different in a liquid; but I am pretty sure the basic principle still applies: the purity of the argon will be a crucial parameter

 

[kimbyd]

Granted, the effect of impurities will be different in a liquid; but I am pretty sure the basic principle still applies: the purity of the argon will be a crucial parameter

That's a very good point. As I understand it, pure water is a pretty good insulator. Nearly all of water's conductivity stems from impurities.

 

[Asymptotic]

That's a very good point. As I understand it, pure water is a pretty good insulator. Nearly all of water's conductivity stems from impurities.

High power radio and radar transmitter tubes once used triple-distilled water as their cooling medium. Several are shown in a photo at the Museum of Radio and Technology website.