120 GPa Just what kind of a chamber can take that pressure?

[alancj]

Ok, according to Wikipedia, Tetraoxygen forms at 20 GPa and turns into a metallic form at 96 GPa. Elsewhere on the web I read that (someone) has tested this solid oxygen at up to 120 GPa which is over 17 million PSI!

So what kind of container would you need to hold that together? How thick walled of a sphere would you need? I wonder how much they are testing; maybe it's pretty small, because I would think you would need a chamber with walls feet thick to stand up to that kind of pressure. I wonder what kind of compressor they're using... I can't imagine getting anything to seal at that pressure.

Does anyone know much about such extreme pressures? Just out of curiosity, if the inner chamber was 10 inches and made of good quality steel how thick walled would a sphere have to be?

-Alan

 

[Rach3]

http://en.wikipedia.org/wiki/Diamond_anvil_cell

 

[alancj]

http://en.wikipedia.org/wiki/Diamond_anvil_cell

That's not very heroic... but interesting nonetheless.

 

[FredGarvin]

Just use the standard hoop stress calculation to get a thickness. It neglects end conditions in pressure vessels, but it would get you in the ball park of what you are looking at. It would also depend greatly on the desired size of the vessel. A smaller vessel would see less stress. It will be huge though for a plain carbon steel. Something to hold back 17 million psi is not going to happen easily that's for sure.

 

[Astronuc]

Pressure like 100's GPa (millions of psi, or 1000's ksi) are pretty much the domain of devices like the diamond anvil. Simply because of the large stress, which are in excess of the ultimate tensile and shear strengths of any material.

The diamond anvil is under compression - not tension - and that is a BIG difference.

The inner core has a pressure of about 350 GPa - http://www.everything-science.com/content/view/21/2/

See also - http://www.llnl.gov/str/Minarik.html