how to build a fusion reactor
Apr. 4th, 2007 04:33 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
zwolThe problem with nuclear fusion is not getting the hydrogen to fuse. No. There are dozens of designs that make the hydrogen fuse, using all sorts of physical techniques — I'll just point to the fusor, because it can be built at lab-bench scale and most people haven't heard of it.
No, the problem with nuclear fusion is that most of the energy produced by the fusing hydrogen comes out in a form that's useless: gamma rays and high-speed neutrons. You have to capture these somehow and convert their energy to a useful form. The most practical way to do that is by surrounding the fusion reaction with a
So what would a better design be? I put it to you that the problem is that the above design is using the wrong fundamental force for the job. The blanket of material is absorbing radiation through electromagnetic interactions; neutrons and gammas don't really do that. The strong force is too short-range, and the weak force is both too short-range and too weak. We got one force left. Gravity.
More after the five PM seminar.
No, the problem with nuclear fusion is that most of the energy produced by the fusing hydrogen comes out in a form that's useless: gamma rays and high-speed neutrons. You have to capture these somehow and convert their energy to a useful form. The most practical way to do that is by surrounding the fusion reaction with a
blanketof material that will absorb the radiation and turn its energy into heat, which you then run through a heat engine to make electricity, which is actually useful. This process is horrifically lossy, involves big complicated machinery, and the blanket eventually becomes radioactive. [There is also a problem with just making the total return energy be more than the energy you put into the machine in the first place, but you will see that my solution to the capturing problem also solves that one.]
So what would a better design be? I put it to you that the problem is that the above design is using the wrong fundamental force for the job. The blanket of material is absorbing radiation through electromagnetic interactions; neutrons and gammas don't really do that. The strong force is too short-range, and the weak force is both too short-range and too weak. We got one force left. Gravity.
More after the five PM seminar.
