One hundred years from now, what will a fusion reactor look like? Most of the ideas described in this chapter will have been discarded, and a few will have been combined. Once the period of patched-up Rube-Goldberg-like experiments is over, private industry will develop a simpler and cheaper system that self — organizes into a stable configuration and keeps itself hot without much external power. The reactor will probably have a roundish shape, like that of a compact tokamak. The fuel will probably be p-B11, which does not require tritium breeding and generates few neutrons. Or it could be d-He3, though He3 would have to be made in an auxiliary fission reactor. The magnetic surfaces will be closed and have the interior good curvature of a spherical tokamak (Fig. 10.12). They may look like those of the Chandrasekhar-Kendall-Furth force-free configuration shown in Fig. 10.56.

There will be natural divertors at the top and bottom. The exterior regions above and below the divertor necks can be expanded like those of an axisymmetric mirror (Fig. 10.27) to create more good curvature for stabilization. High-energy alpha particles leaving the divertors can be channeled into direct converters to generate high-voltage DC directly. The central core can be slid up or down continuously to be refreshed without a shutdown.

This is a dream, but we can hope.

Conclusions

Ah, but a man’s reach should exceed his grasp, or what’s a heaven for?

Never have these oft-quoted words by Robert Browning been more pertinent. The very existence of man depends on his ability to get energy when nature’s bounty runs out. We may not succeed in creating our own Promethean fire, but it’s within reach.

Fusion is a solution to both climate change and energy shortage. Fusion energy is inexhaustible and nonpolluting.

Fusion will cure our dependence on oil. There will be no need to wage wars in the Middle East. With unlimited energy, there will be electricity or hydrogen to run cars.

With unlimited energy, desalination can provide fresh water in all coastal regions.

Fusion cannot explode or be proliferated.

Fusion does not need to disturb the environment or wildlife habitats. Reactors can be located on the sites of aging coal or nuclear plants. In particular, they can be located near population centers. No new cross-country transmission lines need to be built urgently.

Fusion is the only energy source that can sustain mankind for future centuries and millennia. The sooner we get it, the less we need to spend on temporary solutions.