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RE: starship-design: Staged Fusion Power

Steve and Timothy,

>  > What would you use them for?
> Raw energy, of course.  Gamma rays are high-energy photons.

It would seem that if we could somehow reflect this energy back into the
reaction it would provide enough energy to "pump" the reaction. Except of
course that unless it was made to reflect back and forth many millions of
times, it wouldn't hit anything, even at the core of a dense plasma. Ohh

> My brief thoughts on the whole fusion power thing are:
> Any fusion drive that depends on uncommon elements or isotopes
> probably implies that the fuel has to be gathered ahead of time
> and stored on board.  Deuterium, tritium, helium-3, and so on are
> not easy to come by and take significant time and energy to
> refine out of a planetary atmosphere or ocean or the interstellar
> medium.  The main reason such isotopes are considered for fusion
> power plants on Earth is that the lower cost of fusing them looks
> attractive even compared to the cost of refining them out of
> seawater.  For spacecraft fuel I really believe that becomes a
> significant disadvantage.  I think the only mitigating factor is
> that it might not be too expensive to synthesize the uncommon
> isotopes from the far more abundant common isotopes in order to
> be able to run the fusion reactor with lower temperatures.

Actually, this is one of the driving factors behind colonies on the moon.
Both of these elements are very common there and extraction from lunar
regolith of relatively concentrated He3 and Li6 using solar power has GOT to
be cheaper than extraction from seawater.