Carbon nanotube assisted fusion?

This forum is for other possible methods for fusion such as Sonolumenescense, Cold Fusion, CANR/LENR or accelerator fusion. It should contain all theory, discussions and even construction and URLs related to "other than fusor, fusion".
Doug Browning
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Carbon nanotube assisted fusion?

Post by Doug Browning » Sat Mar 17, 2012 3:57 am

This is just an interesting idea:

The scheme:
A carbon nanotube is used here with sufficient ID to accomodate filling with deuterium or hydrogen reactants. The gas fill-up could be done by immersion in high pressure reactant gas to fill it. Then a medium-HV, high current capacitor, with exceedingly low ESR and inductance, gets discharged across the nanotube filament with some kind of very fast switch to activate (spark gap?). High magnetic pinch current would collapse the nanotube down to a near singularity, hopefully causing fusion reactions with sufficient speed as to avoid the usual plasma instabilities. The whole assembly gets replaced after each "shot". Maybe could run large quantities of fibers through a spark gap to fire them off.

Edward Miller
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Re: Carbon nanotube assisted fusion

Post by Edward Miller » Sat Mar 17, 2012 4:56 am

Using nano-materials to assist in fusion is a very interesting area. It is also very slow to implement and expensive.

There are people doing experiments in this area and your design is unnecessarily complicated and would not solve the fusion problem. You can throw electrons at deuterium more easily without any complicated nano-materials. You can't make money burning million dollar chips to get $0.000001 worth of energy.

If you want to come up with something new look more carefully at the problem.

Doug Browning
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Re: Carbon nanotube assisted fusion

Post by Doug Browning » Sat Mar 17, 2012 6:45 am

The scheme is certainly destructive of carbon nanotube material as a consumeable. No chip is needed here particularly, but some electrode structure would be needed. The scheme is rather conventional in it's approach to fusion by magnetic pinch current compression. By starting with a compressed gas fill (and atomic order diameter fiber), less time is available for plasma instabilities to develop before meaningful fuel compression would occur. It could be that the carbon fiber cannot tolerate sufficient current, before vaporizing, to produce useful compression. But then its not hard to make concentric carbon nanotubes, in fact sloppy synthesis almost guarantees that, or CVD can put a metal coating on the fibers. The microscopic output power per nanotube reaction could be overcome by bulk synthesis in a carbon vapor reactor (ie, billions of nanotubes at a time).

For a cheap design, use cheap CVD vapor built concentric nanotubes (easy to produce by the billions under saturated carbon conditions), immerse them in a pressurized chamber to fill them with the reactant gases, and then use a small fan to push them through some heavy tapering gap electrodes (the big capacitor) with appropriate spacing to set them off with a bang. The gap taper (shrink) would pre-align the fibers in the electric field electrostatically before arcing across thru them.

(and maybe with a magnetic field between the electrodes to provide some internal wall buffering for the nanotubes under compression. See: http://www.sciencedaily.com/releases/20 ... 161505.htm )

Latest configuration:

The initial contact with the discharge capacitor electrodes (fast rise time induction) could be a high enough voltage to cause internal ionization of the gas for the Sandia scheme. Then permanent magnets behind the electrodes.

Magnetic pinch pressure varies as B squared, so a linear scaling down of current with diameter would produce the same pinch effect pressure. Apparently only milliamperes are required to fire off a nanotube (correction, see below, much bigger than usual diameter nanotubes are required, so current to fire them will also be much bigger).

Power output considerations for using nanotubes (the extremely small reaction output per tube) could be addressed by bulk processing at each step. Zillions of fibers from CVD synthesis, pump down and reactant fill in bulk, final reaction by blowing them (a small fan) across the tapered capacitor electrodes, with permanent magnet backing for the Sandia axial B field touch. The tapered electrodes allow the fibers to electrostatically pre-align with the E field first (and coincidentally with the constant B field too) before flashover and pinch.

Another approach would be to use the latest nanotube synthesis techniques which produce vertical forests of the nanotubes from a planar surface. A mechanical roller surface could be used and then rotated with another similar roller to make roller to roller nanotube contact for firing these off. (capacitor across the rollers) This could fire off millions per second if needed for some actual power output. Some means to continuously build the nanotubes, fill them and fire them, all on the rollers, would need to be developed.

Late edit:
Power input goes as reaction area x pressure x time and power output goes by volume. The volume is microscopic here, but the reaction time is too. So efficiency (power out / power in) can still be good. (volumetric scaling of efficiency should not be a big factor here.) A high flow rate, as described, could overcome the power output limitation. The Sandia mod is easy enough to implement with permanent magnets anyway. (although not the solid fuel technique they use)

One more concern:
After compressing the nanotube, one does not want to end up with a single file string of nuclei that did not fuse, so the fiber needs to be big enough in diameter to accomodate sufficient fuel to make at least several close packed strings of nuclei for guaranteed fusion interaction. This will require a very considerably larger nanotube than usual I think, but the energetics of bending graphene actually favors a larger tube diameter for fast CVD growth. What is needed is a template on a surface for vertical growth of these larger tubes. A micro-lithographic repeated pattern of "seed" material on silicon wafers might do the job. The wafer pattern approach could also provide for multi-layer nanotube growth patterns if more pinch current carrying capacity is needed.

A patterned CVD growth wafer could also provide some spacing between the vertical growing nanotube patterns for "in situ" fusion reaction of the nanotubes, without blowing away the adjacent nanotubes or cross interfereing with the adjacent magnetic pinch fields. With the wafer sufficiently conductive (a metal base instead of silicon), it could also be used as one terminal of the current discharge electrodes.
Then a scanning probe across the top could fire off nanotubes in large numbers after fuel filling.

Providing the nanotube array vertical CVD growth maintains a flat surface (or some form of Laser surface post trimming, etc can flatten it), two of these wafers could be placed tube-to-tube sides atop each other, and the whole assembly could be fired off at once after fuel filling of the nanotubes. That should get one into significant power output. But this certainly would destroy the CVD "seed" wafers each time.

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Chris Bradley
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Re: Carbon nanotube assisted fusion

Post by Chris Bradley » Sat Mar 17, 2012 10:59 am

Just like Ed says, to ask the question "what happens if we could work out how to stick fusible stuff in a nano-tube/ball space only just big enough for the atoms?" is a question I, personally, think has merit to be asked. And, indeed, if you search on this, there are things to be found on the subject that folks have looked at already.

So I think you've managed to spoil a potentially good question, by trying to answer it.

Doug Browning
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Re: Carbon nanotube assisted fusion

Post by Doug Browning » Sat Mar 17, 2012 4:02 pm

"If you want to come up with something new look more carefully at the problem. "

"And, indeed, if you search on this, there are things to be found on the subject that folks have looked at already."

Well, Wikipedia mentions nanotube cathodes, but that is not exactly what they have in mind I suspect. I found another article maybe of interest, see below.

Doug Browning
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Re: Carbon nanotube assisted fusion

Post by Doug Browning » Mon Mar 19, 2012 5:32 am

You mean this?
http://www.physicsforums.com/archive/in ... 64318.html

It does have some faulty concepts, but some appear to be readily fixable in various ways (mainly straighten it out), except for the reactions punching holes in the nanotubes and the extremely low power output per nanotube. Instead of getting help at fixing it up, the poster got dumped on.

Jerry Biehler
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Re: Carbon nanotube assisted fusion

Post by Jerry Biehler » Mon Mar 19, 2012 9:25 am

Appalled that his idea was shot down in flames by people who knew more than he?

You can't "Secretly Patent" something. It just does not work that way, well, unless it is a issue of national security interest.

Are you sure you are not related to the guy in the other forum?

Doug Browning
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Re: Carbon nanotube assisted fusion

Post by Doug Browning » Mon Mar 19, 2012 3:46 pm

No, I'm not related to the guy who posted that idea. The idea that someone can look at something in just 5 minutes and determine that it is a complete dead end is ridiculous. Almost everything is designed by some collaboration. Expertise over a broad spectrum would be required to evaluate such a problem. Problems can be overcome in various ways.

There must be at least 10 different ways to extend/improve that idea. Straightening the fiber out would be a big start to avoiding Bremsstrahlung along with an axial magnetic field. A Linear induction accelerator collider within a fiber could be made if the primary feeds could be aligned with a fiber somehow (microlithographic chip substrate?). Biggest problem obviously is how to scale it up to billions of fibers per second for any real power output, or use something bigger like hollow fiber optics.

I see the major limitation here. Per reaction power input goes by reaction area x pressure x time and power output goes by volume. The volume is way too low here. No way to fix the flow rate (nanotubes/sec) for a complex setup like this. (see the other scheme I mention above, using filled nanotube with pinch current compression for something that might work for high volume flow rates.)

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Re: Carbon nanotube assisted fusion?

Post by ray@aarden.us » Sat Mar 31, 2012 1:18 am

I totally concur that all ideas should be pursued. . .especially the fun ones.

Whether to initial concept is immediately feasible our just a step does not matter. It is valuable for all ideas to be taken to their logical conclusion. If alternative are found along the way, we just have branches. . .more value to pursue.

To come up with a switch, how about nitrogen laser published in Scientific American in the early 70’s? This was a double copper cladded circuit board. A strip across the center was etched off so there were two conductors on top and one on the bottom. Of course this forms two capacitors with a common base. A choke connected the top two plates. Charge the top and bottom to 10, 20 kV. Now, both the capacitors are charged, the top two at the same potential. At an outer corner, short the top and bottom plates together (pick from many different methods).

Let’s look at the dynamics. Charge flows from the corner of one plate to the other. There will be a charge depletion that radiates radially from that corner at the speed of light in the medium. When the depletion (and consequential voltage drop) reaches the etched edge, it does not pass through the choke. So there is a voltage developed across the gap right at the edge of that radial depletion zone. As the radius grows at the speed of light, the zone of new voltage drop progresses down the gap at the speed of light. What is that? About an inch a nanosecond? So in about 10 ns, the voltage drop traverses that etched gap.

For the nitrogen laser, a chamber was formed over this gap and filled with helium and nitrogen and then a vacuum was pulled. As the voltage drop appeared across the two top plates, there would be an electron emission from one to the other (not a spark). This would excite the nitrogen at that point. As that radial drop progresses down the edge, the nitrogen in the new regions get excited. The nitrogen that was excited first relaxes and emits photons in all directions. The photons in the direction of the more newly excited nitrogen stimulate those nitrogen to emit in unison – coherence.

OK, now we can use this gap to place a nanotube (or more) across the gap. Pull the trigger and the energy in the two distributed capacitors will be shorted by the interposed nanotubes. If you don’t like the idea of the current flowing progressively down the gap, move the shorting point away from the corner to middle of the outer edge. Now, as the depletion zone progresses radially, it will intersect the gap edge almost simultaneously across the edge. Of course, the further the distance between the outer edge and the gap, the greater the radius that reaches the gap and the closer to simultaneous the discharge will be.

Note that a spark gap is not that fast when we are talking about high speed switching. This is true also if we choose to use it to short the two plates. The shape of the leading edge of that depletion zone will partially be controlled by the speed of the shorting switch. So there will be a lot of fun designing fast switches. The best part is that the distributed capacitor amplifies the switch – we only need a small initial switch current; the flow will grow with the radial depletion.

More speculation: This switch was for a laser. Excite the media at one end, progressively down a path, as emission occurs, they propagate in one direction. Will fusion occur similarly? Will there be any coherence in the emission out the other end?

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Re: Carbon nanotube assisted fusion?

Post by ray@aarden.us » Sat Mar 31, 2012 1:50 am

Nanotube might be a valuable container. Let’s look at some properties:

The nanotube geometry is there due to the bonding nature of carbon. Add a hydrogen atom and you have to break bonds and it will no longer have the same geometry or characteristics.

The nanotube has internal space that could accommodate a couple hydrogen atoms across. But if we ionize the hydrogen, there may be higher packing densities possible.

Note that the nanotubes nor the hydrogen need to be in a gas. This could all be in a liquid. As such, protons are much easier to generate and control. In fact, protons can be pumped into the nanotubes. The higher the voltage, the higher the pressure. The liquid properties provide a lot of variance as is the source of protons.

The nanotubes are held together by covalent bonds – on the order of an electron volt in energy. We are going to contain a reaction that may have a recoil many orders of magnitude higher. The nanotube will be gone when using these ballistic methods.

The single walled nanotube holds a couple hydrogen atoms across. Multi-walled nanotubes are typically a wound up sheet so the spacing between subsequent wall is very small. This geometry limits the packing density but it provides another advantage, it limits a lot of activity to two dimensions. With Heisenberg uncertainty, limiting from 3 to 2 dimensions provides potential amplification of action in the remaining two dimensions.

This might be extended to limiting the hydrogen to 1 dimension down the length of the tube. To do this, there would need to be a method to fit the appropriate size atoms internal to the tube so the only remaining room is for protons down the centerline. Such ordering may provide for ‘cooler’ fusion reactions. So rather than needing to crush the nuclei, they may be fused with a rapid but low energy impulse. If the tubes are not broken, the reaction might be cyclic – 60 Hz?

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