After finding the energy harvesting page of Wikipedia, one side of the S2 engine was covered

Humans can only exist on this Earth. But the Evangelion will be able to exist forever, along with the human soul that dwells within it. When the Earth, the Moon and the Sun are all gone, EVA will exist, so long as one person remains. It'll be lonely, but as long as one person still lives... it will be eternal proof that Mankind ever existed.

This was the "vegetative" side.

Now we have the active side, that gets more energy under shorter time, I want to use fusion and nanotechnology to achieve this so...

What are the problems of our current fusion reactor designs, that can be fixed with the ability to build up matter from the atomic scale, and to design and create really small (bacteria levels of small) devices?

  • $\begingroup$ "What are the problems of our current fusion reactor designs (...)?" Apart from the fact that they don't exist? All designs of fusion reactors are in research phase. In best case scenario it will take another decade before proof-of-concepts start producing energy. $\endgroup$
    – M i ech
    Commented Apr 1, 2017 at 20:29
  • $\begingroup$ @Miech Oh... well guess this means that it's appropriate for a sci-fi setting to have nanotech to make them. $\endgroup$ Commented Apr 1, 2017 at 20:33
  • $\begingroup$ The first full-size (500 MW thermal power) experimental fusion reactor, ITER, is currently under construction at Cadarache in southern France. "Construction of the ITER Tokamak complex started in 2013 [..] [t]he facility is expected to finish its construction phase in 2019 and will start commissioning the reactor that same year and initiate plasma experiments in 2020 with full deuterium–tritium fusion experiments starting in 2027" (Wikipedia). There is a lot material about ITER. Find a specific thorny issue and ask about that. $\endgroup$
    – AlexP
    Commented Apr 1, 2017 at 21:05
  • $\begingroup$ I was not sure I understood the question until I read Thucydides' answer. Confused about why, ever, would one want to build a fusion reactor from atoms when we have perfectly cost effective factories for producing metal, wires and other such supplies for building a reactor. Now I assume that you meant an atomic scale reactor? Probably would be helpful to clarify that in the question. $\endgroup$
    – Nolo
    Commented Apr 2, 2017 at 5:28
  • $\begingroup$ See existing posts on nano fusion reactor. ☺ $\endgroup$
    – JDługosz
    Commented Apr 2, 2017 at 6:05

4 Answers 4


I think the problem is many people assume that "nano" is a sort of magic solution you can sprinkle over a problem like fairy dust.

Nano means "one billionth", so things at the nano scale are on the order of sizes of bacteria or Virii. A typical fusion reactor design like ITER or the laser fusion devices at Lawerence Livermore Labs fill factory sized buildings are are the size and cost of aircraft carriers. Even "new" fusion devices like Polywell or Focus Fusion are still large devices which fill rooms. Building devices these sizes from nanoscale assemblers really only adds quality control (precision placement of atoms), but the physical principles behind these machines isn't changed by this.

What we should be looking for is a way to leverage nanoscale phenomena to make a fusion reactor. The Foresight institute published a paper: Non-Statistical Fusion Reactions In Atomic Scale Accelerators

If we imagine the individual atoms as marbles, this can be thought of as taking a wooden board and carving straight channels for the marbles to roll down. By rolling the marbles fast enough at each other on the tracks or at fixed targets, they are much more likely to impact directly and have a much better chance to achieve fusion.

For actual power generation, we would have to create a device with hundreds or thousands of parallel channels to accelerate the nuclei at each other, and of course there will have to be some method of extracting energy from the thousands of individual reactions, but using nanoscale technology, we potentially can build a fusion reactor the size of a laptop computer (including all control and energy extraction equipment), which is certainly much more practical than something the size of an aircraft carrier.


In addition to the power generation problems mentioned by L.Dutch, the fusion type that we would be doing (D-T, probably) produces lots of high energy neutrons.

While I am optimistic that a net positive power generating tokamak fusion reactor could be developed in the near future using the D-T reaction and enough money, this still leaves significant materials science problems for how to avoid neutron embrittlement and irradiation.

Developing materials with excellent neutron absorption properties (for example, properties like those of Hafnium) seems to me the most logical area for nano-technology to be useful.

  • $\begingroup$ Wondering if you've heard about General Fusion and their mechanical, liquid metal core fusion approach? Seems to me to be more practical than big budget tokamaks. $\endgroup$
    – Nolo
    Commented Apr 2, 2017 at 5:13

What are the problems of our current fusion reactor designs

The material undergoing fusion is really really really hot, so hot that no material can contain it. The only effective containment we know is done by gravity in stars. What is currently being tried on earth is to confine it by using magnetic fields or laser, but the problem is that these still use more energy or at best the same energy generated by the fusion.

What are the problems of our current fusion reactor designs, that can be fixed with the ability to build up matter from the atomic scale

Nanotechonology (which by the way refers to things sized around the nanometer, while bacteria-sized things are used in MEMS) can maybe used to dramatically improve the lasers and make them more efficient, so that less energy is needed to achieve the same confinement.

For a true industrial demonstration, further work is required. In particular, the laser systems need to be able to run at high operating frequencies, perhaps one to ten times a second. Most of the laser systems [...] have trouble operating even as much as once a day.


Rather than smashing nuclei together at high energy (even with tiny devices), look at careful finesse over quantum states instead. This earlier answer explains in detail. I think of real-world examples where quantum effects are found in biological systems.

Even if something deservingly called “cold” fusion is not possible, the general idea is to use fine care in handling rather than raw power. My write-up doesn’t require true cold fusion because the mechanism is destroyed in use. Hold the protons in position, give them a carefully measured amount of energy, and bring them together.

Perhaps some kind of quantum operations can be performed on super cold atoms instead, such that there is a high probability of the two protons being in the same position when the state collapses. This might be called “tunneling fusion” and certainly deserves the term cold!

(source: wikimedia.org)
The wrong BEC.

This is alluded to in the “ratcheting up/ratcheting down” technology of Wil McCarthy’s novel Bloom.

  • $\begingroup$ So, you suggesting to build a machine that increases the chances of quantum tunneling in an atom, as a way to "phase through" the electron cloud? $\endgroup$ Commented Apr 2, 2017 at 9:28
  • $\begingroup$ The electron is a non problem, easily removed. The protons repel and don’t like to get close together. $\endgroup$
    – JDługosz
    Commented Apr 2, 2017 at 11:18
  • $\begingroup$ Would this process cost more energy than it's output? $\endgroup$ Commented Apr 2, 2017 at 11:26
  • $\begingroup$ Well that would be pointless if it were the case. Since you're not heating everything to 50 million degrees, it requires very little energy to run. $\endgroup$
    – JDługosz
    Commented Apr 2, 2017 at 23:59

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