[ExI] Gallium

[Keith Henson]

There are aspects to power satellites that you don't run into often.
Like, is there enough gallium to make multi junction concentrated PV
cells for power satellites?

For that matter, is there enough to make 30 TW of solid state
microwave amplifiers for the transmitters?  The element is a byproduct
of purifying aluminum oxide and the supply can't be greatly enlarged.

The alternative to PV is thermal systems, either steam of SC CO2.
Both are around 40% without and close to 50% with a topping cycle.

If there just isn't enough gallium for the transmitters, can we use
silicon?  Alternately, will vacuum tubes of some sort work?

If you don't think this is a good topic for the Exi list, you can
reply privately or over on Power Satellite Economics.


Keith