Electrostatic atmospheric confinement

Calliban · 2024-03-07 09:08:41

Tom's recent discussion on magnets got me thinking about some things.

I have often wondered if it would be possible to confine an atmosphere to a body using an electric field. It would look something like this.

The body would be a hollow metal sphere, filled with metallic powder, which provides capacitance. The material inside the metal sphere is charged positive. Above the sphere, we place a layer of insulative rock. Above this, we have an atmosphere. Above the atmosphere, we have a negatively charged ionosphere. The voltage gradient between the inside of the sphere and the ionosphere, pulls the ionosphere down, exerting enough pressure over the atmosphere to hold it onto the surface. The insulative layer of rock has sufficiently high breakdown voltage to prevent the charges from flowing and cancelling each other. So long as the ionosphere retains its negative charge and the interior its positive charge, the atmosphere remains on the surface of the body.

There is probably a simple reason why this would not work. Even in the ionosphere, there are still neutral atoms that would not be effected by the electric field. And the amount of charge that must be stored to contain an atmosphere in this way would be immense. But can anyone provide a physics based proof for this not working?

In much the same way, a strong magnetic field can be used to contain a plasma. Provided the beta (ratio of magnetic pressure to plasma pressure) is high enough, then charged particles remain trapped. Could a cold plasma, be used to confine a breathable atmosphere to a small body? What sort of power requirement would this entail?

Last edited by Calliban (2024-03-07 09:15:18)

tahanson43206 · 2024-03-07 09:28:11

This post is reserved for an index to post NewMars members may contribute over time.

Best wishes for success with this topic. It may evolve over time, as similar but perhaps presently unknown containment methods are discovered.

You can change the title by editing Post #1 at any time, so if something new does show up, you can merge it without difficulty.

Startrek was full of currently unknown technology, but on the other hand, the hand held communicator is a reality in the Real Universe.

Anti-Matter propulsion and the replicator are still unrealized, but there are already hints of how they might be achieved.

If there is a NewMars reader who would like to help Calliban with this topic, please see the Recruiting topic for procedure.

(th)

Calliban · 2024-03-07 10:15:35

For this idea to work, the breakdown voltage gradient of gas in the ionosphere must be lower than the gas in the atmosphere proper. Some barrier would be needed to prevent the two layers from mixing. As there will be no pressure difference between them, that barrier couod be an inflatable plastic sheet.

kbd512 · 2024-03-07 11:38:32

Calliban,

How does the electrically conductive dust in the Martian atmosphere affect this atmospheric retention concept?

Calliban · 2024-03-07 16:13:05

kbd512 wrote:

Calliban,
How does the electrically conductive dust in the Martian atmosphere affect this atmospheric retention concept?

I wasn't really thinking of Mars, but something much smaller. Suppose we were to make a hollow metal ball 10km in diameter and cover it with a layer of non-conducting rock, like fused silica. Add fine dust to the interior void in the ball to serve as an electrostatic surface. Then establish a charge differential between the interior of the ball and ionised gas above it. Positive ions in the gas will be drawn to the trapped negative charge inside the ball, pulling them to the surface. But the layer of non-conducting rock will prevent transfer of charge provided that voltage gradient does not exceed the breakdown voltage of the rock. So the electrically charged atmosphere should remain stuck to the surface of the ball.

I am pretty certain that this idea won't work. I think the capacitance needed to confine any significant atmosphere would be immense. I am being a bit lazy not getting drawn into the maths. That is what is needed to test the idea.

Even if it could work, creating a world that requires a continuously functioning electric field to maintain its atmosphere, seems like a really bad idea. It is one thing relying on passive features like pressure vessels to keep the air in. Living under an electrostatic forcefield that could disappear if there is a short circuit would keep most colonists up at night.

Last edited by Calliban (2024-03-07 16:18:27)

SpaceNut · 2024-03-07 18:40:35

Artificial Magnetosphere - Electromagnetic Induction

Calliban · 2024-03-11 17:10:25

Plasma becomes increasingly viscous as its temperature rises. A plasma window exploits this effect. It functions rather like a forcefield, trapping plasma in a magnetic field, which prevents air from crossing it due to the viscosity of the plasma.
https://en.m.wikipedia.org/wiki/Plasma_window

The small windows created so far are used in electron beam welding. They are extremely power hungry. But it stands to reason that any body surrounded by a powerful magnetic field in space, will trap solar wind particles. If such a body is then allowed to accumulate an atmosphere, the trapped plasma will form a barrier to escape of air molecules. Obviously, the plasma pressure at the top of the atmosphere must be equal to atmospheric pressure there. Likewise, the plasma pressure must be less than the magnetic pressure or particles will cross the field lines and escape.

One way of doing this would be to put a superconducting ring under the crust of an asteroid. The asteroid surface will provide insulation, allowing the superconductor to remain cold with minimal power consumption. It turns out that thermal conductivity of most solids, declines as temperature approaches 0K.
http://uspas.fnal.gov/materials/19NewMe … re%204.pdf

The weight of the crust will counteract the expansive pressure resulting from the current. Once current is established in the ring, the field will remain stable without additional power. Such a plasma confined atmosphere could remain stable for geological timescales.

Aluminium has a critical temperature for superconductivity of 1.18K. This may be the most suitable material for a superconductor given its abundance.
https://en.m.wikipedia.org/wiki/Superconductivity

Last edited by Calliban (2024-03-11 17:33:12)

tahanson43206 · 2024-03-12 08:19:05

For Calliban re Void's idea ....

While the idea of using a material (ie, glass) seems a bit of a stretch from your opening vision, I am hoping you and Void will see if there is anything that might be done with it ... I understand that the force holding atoms in a solid form (ie, glass) is electrostatic force, although the electrons that facilitate the force are moving like crazy in their orbits.

Thus, with a bit of stretching, Void's suggestion ** might ** be considered as fitting into the concept of the topic.

In any case, I'm hoping the two of you will be willing to see if you can do anything more with Void's suggestion.

A soap film is an example of a structure held together by electrostatic force. A soap film is only a starting point, of course, because one of those does not heal itself if it is penetrated by a sharp instrument. The equivalent structure to hold atmosphere around a solar system object would need to be self-healing, since every few moments a micro-sized object can be expected to pass through the area.

Never-the-less, the two of you may be able to imagine a material that can provide the atmosphere containment service, while being self-healing and perhaps even able to pick up energy from photons passing by, wheher in or out bound.

(th)

Calliban · 2024-03-12 09:06:55

A magnetic field holding a viscous plasma appears to be a better approach than electrostatic confinement.

I ran a few calculations to determine how strong a magnetic field would need to be to confine a 0.3 bar, breathable atmosphere to an asteroid using a plasma window. The magnetic field would contain a plasma, or ionosphere, which would function as a plasma window, preventing air from crossing it. To create this magnetic field, we would run superconducting cables under the surface of the asteroid. How strong would the field need to be? Magnetic pressure is defined as:

PB = B^2/2u0

Where B is in tesla and u0 is the vacuum permeability: 1.26E−6 N.A-2.

Solving the equation yields a value of 0.275T to yield a magnetic pressure of 0.3bar. Suppose we create this field using superconducting wire running under the crust. Yttrium-barium-copper oxide superconductors can support current density up to 90MA/cm2.
https://www.nature.com/articles/s41598-021-87639-4
https://en.m.wikipedia.org/wiki/Yttrium … pper_oxide

Suppose we put the wire 5km under the crust. The plasma-air interface is located some 5km above the crust, to allow for any topography on the asteroid surface. The cables are spaced roughly 5km apart. How much current would each cable need to carry and how thick would it be? For a wire, magnetic flux at distance r is given by:

B = (u0 x I) / (2 x pi x r), where I is current in A.

Solving for r =10,000m and B = 0.275T, gives I of 13.727 billion amps. If the superconducting cable can achieve a current density of 90MA/cm2, then the required cross section of cable would be 152cm2. This translates to a cylindrical cable some 14cm in diameter.

Let us take the example of an asteroid some 100km in diameter. Total surface area wouod be 31,416km2. With cables spaced 5km apart, we need a 1km length of cable for every 5km2 of surface, making for 6283km of cable overall. The equates to some 96,722m3 of superconductor material. The density of this material 6.4g/cm3, giving a total mass of 600,000 tonnes, or 19.46 tonnes per km2. We would need 80,000 tonnes of yttrium to make this much YBCO. This sound like quite a lot. But yttrium is 400x more common than silver. So maybe it could be done.

I would agree that paraterraforming is technically easier. We could support a relatively thin transparent shell using tensile steel members, anchored deep beneath the crust. But it may be less resiliant. Those tensile members have a fatigue life measured in decades rather than centuries. And a meteorite coukd punch a hole in any roof structure. It is much harder to disrupt a cable that is several km beneath the surface.

Last edited by Calliban (2024-03-12 09:14:46)

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#1 2024-03-07 09:08:41

Electrostatic atmospheric confinement

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