Tag Archives: architecture

Will plasma be the new glass?

Now and again, everyone gets a chance to show the true depths of their ignorance, and I suspect this is my chance, but you know what? I don’t really care. I have some good ideas as well as dumb ones, and sometimes it is too hard to know which is which. I freely admit that my physics is very rusty. However….

Plasma is essentially a highly ionised gas; lots of ions and free electrons. It conducts electricity so is ideally suited to magnetic confinement. You make a current in it, and use magnetic field interaction with that current to hold it in place.It can also hold a decent charge overall, positive or negative. That means it interacts electrostatically as well as magnetically. Electromagnetics is all one big happy field anyway.

A strong magnetic field can be made that encompasses the plasma magnetically without it needing to be surrounded by a solid object. Let’s do a thought experiment.

Start off with a sealed ball and make a small hole in it, put an electric coil around the hole, send some current through it, and make a field around that hole to stop plasma escaping. Ditto the opposite side of the ball, so now you have a tube with plasma in it, albeit a fat tube with narrow ends. Gradually make the hole diameters bigger and bigger, and the tube shorter and less curvy. Eventually you will have more or less a fat disk of plasma. The relative dimensions of the disk will depend on the intensity and control of the magnetic field, the ionisation of the plasma and any currents you make in it.

With some good physics and engineering, adequate sensing and a decent control system, I reckon it should be possible to make reasonable sized disks of plasma. So, make two of them. Put the two disks reasonable close and face to face. Arrange them so that the electric currents in the plasmas run in different directions too. If they are both similarly charged overall they will repel electrostatically and their internal magnetic fields will also interact, but the managed applied magnetic fields could stop them deforming too much. Add more disks, and we have plasma plywood. Let’s call it plasma-ply for lack of a better word.

I can’t calculate how thin this plasma-ply could be made. I suspect that with future materials such as graphene and room temperature superconductors, future remote sensing and advanced computer control systems, they could be pretty damned good. If you try to deform one of these disks, it would resist, because the magnetic and electrical interactions would create force to keep it in place. We have another name for that. We call it a force field and we see them in every space opera. If the surrounding coils and other stuff is just a think ring, as you’d expect, you’d have a round window. Maybe a smallish window, but you could use a lot of the coils to make a big window in a honeycomb structure.

So we can bin the word plasma-ply and start using the words we already have. We will have force fields and plasma windows. Plasma will be the new glass, and an important 21st century building material.

3D printing the highest skyscraper? 600km tall structures may be feasible.

What would you do with a 600km high structure? That would be hundreds of times higher than the highest ever built so far. I think it is feasible. Here I will suggest super-light, super-strong building materials that can substitute for steel and concrete that can be grown up from the base using feasibly high pressures.

I recently proposed a biomimetic technique for printing graphene filaments to make carbon fur (- in this case, for my fictional carbon-obsessed super-heroine Carbon Girl. I am using the Carbon Trio as a nice fun way to illustrate a lot of genuine carbon-related concepts for both civil and military uses, since they could make a good story at some point. Don’t be put off by the fictional setting, the actual concepts are intended to be entirely feasible. Real science makes a better foundation for good science fiction. Anyway, this is the article on how to make carbon filaments, self-organised into fur, and hence her fur coat:)

http://carbondevices.com/2013/07/01/carbon-fur-biokleptic-warmth-and-protection/

Here is the only pic I’ve drawn so far of part of the filament print head face:

printing graphene filaments

Many print heads would be spread out biomimetically over a scalable area as sparsely or densely as needed, just like fur follicles. A strong foundation with this print head on top could feasibly form the base of a very tall vertical column. If the concept as described in the fur link is adapted slightly to print the filaments into a graphene foam medium, (obviously pushed through the space between the follicles that produce the filaments) a very lightweight foam structure with long binding filaments of graphene graphene foam would result, that would essentially grow from the ground up. This could be very strong both in compression and tension, like a very fine-grained reinforced concrete, but with a tiny fraction of the weight. Given the amazing strength of graphene, it could be strong enough for our target 600km. Graphene foam is described here:

http://timeguide.wordpress.com/2013/01/05/could-graphene-foam-be-a-future-helium-substitute/

Extruding the supporting columns of a skyscraper from the ground up by hydraulically growing reinforced graphene foam would certainly be a challenging project. The highest hydraulic pressures today are around 1400 bar, 1.427 tonnes per sq cm. However, the density of graphene foam with graphene filament reinforcement could be set at any required density from below that of helium (for graphene spheres of 0.014mm with vacuum inside), to that of solid carbon if the spheres are just solid particles with no vacuum core. I haven’t yet calculated the maximum size of hollow graphene spheres that would be able to resist production pressures of 1400 bar. That would determine the overall density of the material and hence the maximum height achievable. However, even solid carbon columns only weigh 227g per metre height per sq cm of cross-section, so even that pressure would allow 6.3km tall solid columns to be hydraulically extruded. Lower densities of foam would give potentially large multiples of that.

This concrete substitute would be nowhere near as strong as basic graphene, but has the advantage that it could be grown.

(The overall listed strength of solid graphene theoretically allows up to 600km tall, which would take you well into space, perfect for launching satellites or space missions such as asteroid mining. But that is almost irrelevant, since graphene will also permit construction of the space elevator, and that solves that problem far better still. Still, space elevators would be very costly so maybe there is a place for super-tall ground-supported structures.)

But let’s look again at the pressures and densities. I think we can do a lot better than 6km. My own proposal a while back suggests how 30km tall structures could be built using graphene tube composite columns structures. I did think we’d be able to grow those.

http://timeguide.wordpress.com/2013/02/22/super-tall-30km-carbon-structures-graphene-and-nanotube-mesh/

We’d need higher pressures to extrude higher than 6km if we extruding solid columns, but these tube-based columns with graphene filament reinforced graphene foam packing would have a far lower density. The print heads in the above diagram were designed to make fur filaments but I think it is possible (though I haven’t yet done it) to redesign the print heads so that they could print the tubular structures needed for our columns. Tricky, but probably possible. The internal column structures are based on what nature uses to make trees, so are also nicely biomimetic. If we can redesign the print heads, then printing low density columns using a composite of filament reinforced foam, in between graphene tubes should work fine, up to heights well above the 30km I originally suggested. An outer low pressure foam layer can be added as the column emerges. It doesn’t have to withstand any significant pressure so can be as light as helium and add the strength needed to prevent column buckling. With the right structure, perhaps the whole 600km can be achieved that way. Certainly the figures look OK superficially, and there’s no hurry. It’s certainly worth more detailed study.

Super-tall (30km) carbon structures (graphene and nanotube mesh)

I recently blogged about a 200km moon-based structure. Here is my original earth-based concept, which could now be enhanced by filling columns with graphene foam

http://timeguide.wordpress.com/2013/01/05/could-graphene-foam-be-a-future-helium-substitute/

How about a 30km tall building? Using multilayered columns using rolled up or rippled graphene and nanotubes, in various patterned cross sections, it should be possible to make strong threads, ribbons and membranes, interwoven to make columns and arrange them into an extremely tall pyramid.

Super-tall structures for science and tourism

Think of a structure like the wood and bark of a tree, with the many tubular fine structures. Engineering can take the ideas nature gives us and optimise them using synthetic materials. Graphene and carbon nanotube will become routing architectural materials in due course. Many mesh designs and composites will be possible, and layering these to make threads, columns, cross members with various micro-structures will enable extremely strong columns to be made. If the outer layer is coated to withstand vacuum, then it will be possible to make the columns strong enough to withstand atmospheric pressure, but with an overall density the same as the surrounding air or less. Pressure is of course less of an issue higher up, so higher parts of the columns can therefore be lighter still.

We should be able to make zero weight structures in lower atmosphere, and still have atmospheric buoyancy supporting some of the weight as altitude increases.  Once buoyancy fails, the structure will have to be supported by the structure below, limiting the final achievable height.  Optimising the structures to give just enough strength at the various heights, with optimised mesh structure and maximal use of buoyancy, will enable the tallest possible structures. Very tall structures indeed could be made.

So, think of making such a structure, with three columns in a triangular cross-section meeting at 43 degrees at the top (this is the optimal angle for the strongest A frame in terms of load-bearing to weight ratio, though that is a simplistic calculation that ignores buoyancy effects, so it ‘needs more work’.

Making a wild guess, 30km tall structures may be feasible, but that is just a wild guess and I would welcome comments from any civil engineers or graphene architects. These would not be ideal for habitation, since most of the strength in the structure would be to support the upper parts of the structure itself and whatever platform loading is needed. The idea may be perfect for pressurised platforms at the top for scientific research, environmental monitoring, telescopes, space launches, tourism and so on. The extreme difference in temperature may have energy production uses too.

Getting the first 30km off the ground without needing any rocket fuel would greatly reduce space development costs, not to mention carbon and high altitude water emissions.

A simple addition to this would be to add balloons to the columns at various points to add extra buoyancy. I dare not try to calculate how much higher this would permit, but I suspect not all that much more since even with balloons, they cannot give much extra lift once the atmosphere is too thin.

Could graphene foam be a future Helium substitute?

I just did a back-of-the-envelope calculation to work out what size of sphere containing a vacuum would give the same average density as helium at room temperature, if the sphere is made of graphene, the new one-size-does-everthing-you-can-imagine wonder material.

Why? Well, the Yanks have just prototyped a big airship and it uses helium for buoyancy. http://www.dailymail.co.uk/sciencetech/article-2257201/The-astonishing-Aeroscraft–new-type-rigid-airship-thats-set-revolutionise-haulage-tourism–warfare.html

Helium weighs 0.164kg per cubic metre. Graphene sheet weighs only 0.77mg per square metre. Mind you, the data source was Wikipedia so don’t start a business based on this without checking! If you could make a sphere out of a single layer of graphene, and have a vacuum inside (graphene is allegedly impervious to gas) it would become less dense than helium at sizes above 0.014mm. Wow! That’s very small. I expected ping pong ball sizes when I started and knew that would never work because large thin spheres would be likely to collapse. 14 micron spheres are too small to see with the naked eye, not much bigger than skin cells, maybe they would work OK.

Confession time now. I have no idea whether a single layer of graphene is absolutely impervious to gas, it says so on some websites but it says a lot of things on some websites that are total nonsense.

The obvious downside even if it could work is that graphene is still very expensive, but everything is when is starts off. Imagine how much you could sell a plastic cup for to an Egyptian Pharaoh.

Helium is an endangered resource. We use it for party balloons and then it goes into the atmosphere and from there leaks into space. It is hard to replace, at least for the next few decades. If we could use common elements like carbon as a substitute that would be good news. Getting the cost of production down is just engineering and people are good at that when there is an incentive.

So in the future, maybe we could fill party balloons and blimps with graphene foam. You could make huge airships happily with it, that don’t need helium of hydrogen. 

Tiny particles that size readily behave as a fluid and can easily be pumped. You could make lighter-than-air building materials for ultra-tall skyscrapers, launch platforms, floating Avatar-style sky islands and so on.

You could also make small clusters of them to carry tiny payloads for espionage or terrorism. Floating invisibly tiny particles of clever electronics around has good and bad uses. You could distribute explosives with floating particles that congeal into whatever shape you want on whatever target you want using self-organisation and liberal use of EM fields. I don’t even have that sort of stuff on Halo. I’d better stop now before I start laughing evilly and muttering about taking over the world.