Thoughts on Fusion reactor design

When it comes to some science topics, I’m more than just an interested bystander. I like to look at things, and ask questions about how they go together. Tinker with ideas and try to bolt them into a narrative.

Something that’s been bouncing around in my mind over the past five years has been how to build a working Nuclear Fusion reactor. What would it look like? How would it actually work on a semi continuous basis? Now I’m going to exclude ‘cold’ Fusion from today’s little rambling because, well, just because I don’t want to go there. Mainly because I don’t think it can or will work. Fusion needs thousands of degrees of heat and many atmospheres of pressure to slam all those light nuclei together to fuse and produce energy as they do so. Anything else is just chemistry.

Nuclear Fusion at present has been achieved in it’s crudest form as the Hydrogen bomb. A Fission trigger detonates and slams a lot of Tritium and Deuterium together with a resultant massive release of energy in a multi megaton explosion. Tokamak reactor designs have come close, and firing a humungous laser at a tiny pellet of fuel also promises a positive result, all conditions being perfect. The ITER showed promise, but last I heard was suffering with issues surrounding superconductor failures. There’s also a thing called a Polywell, which is the brainchild of the late Dr Robert Bussard. This too shows promise, and I think the idea is sound, but the execution leaves something undone. All of these approaches have one thing in common; they require more energy input than they produce.

My (albeit fictional) preference is for a merging of the two solutions, where the tight plasma toroids of a Tokamak type design are merged with the Polywell concept. In shape, the plasma flows would resemble eight ring doughnuts stood on edge in a circle so that the plasma streams all merge at a highly contained central point. Thus forming a plasma flow point of confluence in a central containment core. See flow diagram. The stylised sun indicates where the actual point of reaction should take place, the top red arrow shows the direction of fuel injected into the charged plasma, and the yellow arrow the excess ‘exhaust’.

One of the problems with the aforementioned approaches to Fusion is plasma requiring very heavy magnetic containment to prevent it arcing or in electrical terms, shorting to earth. There may be an answer to this issue and I saw it hidden in a report on an Italian experiment in 2008/9, where an electrical charge was applied to a plasma stream, which then self organised itself into a helix, or corkscrew shape. This was replicated by an American team led by Ray Fonck at the University of Wisconsin, as reported in this 2009 news item.

Now if eight lower energy helical plasma streams could be guided into a central area of heavy containment, where the little sun is in my rather crude diagram, then I wonder if my Tokamak / Polywell hybrid concept might actually work? If the Pegasus team in Wisconsin have found a way which makes Tokamaks easier to build, perhaps taking a mental sideways step and combining the approach with another might just lead closer to the dream of working sustainable nuclear fusion?

Now I appreciate I’m no Physicist. My original work training was in Electrical Engineering, mostly power distribution. Nowadays I write slightly geeky science fiction which hardly anybody reads for goodness sake. Yet no matter which direction I look at the subject, I’m left with this overpowering gut feeling that a hybrid approach might be the answer.