Deep Sea Base - Why be there? The Diamond Anvil Cell

[DeepSeaBase]

So the question arises, why be at the bottom of the sea? The international space station has a lot of scientific experiments that can only, or best be performed in microgravity. So I ask the question what experiments can best be performed at the bottom of the sea? What comes to mind is the pressure. Immense pressure.

Almost 2x the pressure that we can generate with pump technology. 690bar seems to be the upper limit of pump technology, but Challenger Deep rests at 1014 bar. And so I suggest that there is opportunity for experiments here. Enter the "Diamond Anvil Cell."

https://home.hiroshima-u.ac.jp/kawazoe/html/Kawazoe04-Method-EN.html

https://www.sciencedirect.com/science/article/pii/S167498711000037X?via%3Dihub

https://www.apexhydraulics.co.uk/guide-hydraulic-cylinders/#:~:text=Therefore%2C the weight that can,the range%3B around 210 Bar.

 

So, the problem with diamond anvil cells is they have to apply pressure on a very small area. This comes from limitations of the apparatus due to pressure seals, hydraulic fluids, and at 690bar, the larger size of the hydraulic ram.

I propose that the hydraulic ram can be simplified, exposing the head of the cylinder to ambient sea pressures, and use ~1014bar pressure instead of 690bar.

As such, a 9inch radius cylinder would produce 25GPa over a square inch. This is an increase in performance of a Diamond Anvil Cell by some 25,400x.

That's a huge performance increase.

All we have to do is develop the machinery to use the ocean pressure to drive the rams. I've drawn a basic idea built off a pressure hull design. But I'm still intently working on the thought process for this.

Including checking to see if there's anything in the design of the Diamond Anvil Cells and their various types of construction that prevents adaptation to the ocean pressure, or negates the need for it such as it has higher performance than 1014bar and I misunderstood something in its hydraulic design.

As for the pressure hull drawing, I think it may be possible to develop a pinhole design to equalize the pressure of a hydraulic fluid (water) in the cylinder head. Such a design may better secure the pressure hull than the large hatch design I present.

[John Cuthber]

Interesting , but impractical.

Those observing the experiment would drown.

 

I'm kidding, but the "observers" of these experiments are things like X-ray machines and lasers which don't take kindly to salt water.

[DeepSeaBase]

6 hours ago, John Cuthber said:

I'm kidding, but the "observers" of these experiments are things like X-ray machines and lasers which don't take kindly to salt water.

As far as I'm considering, the module itself will remain dry. While the pistons are exposed to ambient sea-pressure, the module will be designed such that a hull breach/leak doesn't form.

What I'm struggling with more is proving that such a contraption is superior to just a super high pressured pump....

 

Such pumps can reach 2000 bar and are used for diamond anvil cells, but the cells are still quite small. So I don't know if the cells are pressure limited i.e. the pump can only move so large a cylinder, or if its materials limited, or both.

I'm trying to conceptualize how the super high pressure pumps work to be the "primary driver" of a diamond anvil cell, so that I can thought-experiment whether or not it is more efficient or more scalable to put the anvils under the ocean and let the ocean depth become the primary driver.

[Enthalpy]

I already used hand pumps, from the catalogue, that create 150MPa (1500bar). Long lever, small piston, big pressure - with stiff parts and good seals.

So I don't feel the necessity of sea pressure to achieve 110MPa. A lab and a pump feel more comfortable to me.

Diamond anvils are often moved by screws. They achieve pressure far bigger than the Ocean does.

The Ocean floor (most is at -3 000 m, while -11 000 m is rare) may have other advantages, like fewer cosmic rays. I'm not quite sure why some countries are interested now (or were few years ago): methane is one incentive, metals may be one other. Above all, submarine war.

[DeepSeaBase]

On 5/8/2021 at 5:54 AM, Enthalpy said:

I already used hand pumps, from the catalogue, that create 150MPa (1500bar). Long lever, small piston, big pressure - with stiff parts and good seals.

TL;DR - I'm keeping Diamond Anvil Cells in the "Improbable" category of why a deep sea base....I've been looking into other reasons this weekend focusing mostly on biotechnology.

There's actually 4,000 bar hand pumps. So something is missing, because I just talked to a researcher at Oak Ridge National Laboratory and they are fascinated by the idea of a 6,500 ton press to create 100GPa pressure on 1 inch-square.

Long story short: I'm still hopeful that a deep ocean high pressure anvil for large volume material synthesis (phew that's a mouthful) will be a thing....

But, unfortunately it's nowhere NEAR as straightforward as just comparing strength of pumps.
 

On 5/8/2021 at 5:54 AM, Enthalpy said:

Diamond anvils are often moved by screws. They achieve pressure far bigger than the Ocean does.

This is correct, I have used a research paper from Cornell University's Department of Geological Sciences to define all the "force provider" types of the typical anvils, and inquired at the Stony Brook University for how they are providing force to their multi-anvil system (they are leaders in that field). Lastly there's the Kawai-type anvil press.

Basically, there's dozens of methods of trying to get hundreds of gigapascals pressed onto tiny objects usually micrometers in size but sometimes as high as 1mm^3 to even 10cm^3 for the few gigapascals.

Of all these methods, the Oak Ridge Laboratory person seemed quite fascinated at the idea of generating hundreds of gigapascals over more than a square inch.

A 6500 ton press to work a square inch is actually quite a lot of hydraulics. No "4,000 bar" hand pump is going to move that thing....and while 50,000 or even 80,000 ton presses exist, they are also the size of buildings.

Then comes the technical issue of marrying the press to a diamond anvil. And in the case of Gigapascals of pressure it's also material limited. Single diamond crystals are required to make larger cells that can withstand those Gigapascals.

So they are limited on size based on the crystal size.

Edited May 10, 2021 by DeepSeaBase

[Enthalpy]

For really big forces, I'd go back to screws and electric motors. They are not as flexible as hydraulics, but they're more compact. Ball screws would save torque if they're compact enough, which I doubt, so the screw would rather glide against the nut. I got very small friction coefficient from a layer of nickel with embedded Ptfe (or a layer at each mating face, this won't gall) plus MoS₂ grease.

You may find this very hypothetical synthesis of cubane fun:
chemicalforums
I ignore if it needs light, for ethylene 2+2 cycloaddition it's 172nm. For fast production, a quick cycle of the diamond anvil brings as much as a bigger anvil.