Reactivity · Bosch–Hale
Why the fuels differ.
These are the Bosch–Hale fusion reactivities <σv> computed live from the deposited
kronos_clean.sigmav() coefficients — the same kernel both
machines use. They are the reason fuel follows purpose: D–T lights first, so HYPERION burns it to breed;
D–³He turns on an order of magnitude hotter, paying back in charged products instead of neutrons, so the generator
burns it to convert directly.
starting …
D–T peak
~70 keV
lights first — the breeder fuel
D–³He peak
~250 keV
hot — the generator fuel
D–D
weakest
never closes in a mirror
What the curves say
A generator that converts charged particles directly wants a fuel whose energy comes out
charged, not as
neutrons — that is D–³He, but it only becomes reactive at ion temperatures near 100 keV, which is why the design is
a high-temperature tandem mirror rather than a tokamak. A breeder only needs
gain, and D–T's reactivity
makes that reachable at a modest current — so HYPERION burns D–T. Source:
the breeder deposit ·
kronos_clean.py.