QuantumDot wrote:
controlling thermal emission radiation

Micropits are an excellent way of increasing
emissivity, and there’s ongoing research on using
atomic oxygen to pit standard radiator surfaces*,
but it seems that the fancy shutters described in
that link would be a waste of time for a spacecraft
trying to deal with heat in the megawatt range.

*(The atomic oxygen in LEO is always too busy
trying to eat the things you don’t want it to eat to
be bothered with evenly pitting a given surface 🙂 ).

QuantumDot wrote:
micron-gap thermal photovoltaics

This could be excellent if it compares favorably
with the equivalent increase in power/radiators in
mass and volume.

But the recovery of 80% of the thermal from reactor
and drives as electric would do great
things for radiator size etc if the mass of the dots
gear doesn’t eat the margin gained.

With the current stats that would give us a DPF
box running at .35 MWe (!) and a double-faced
radiator of 66 m2… a square just over 8 meters on
a side that masses 1.3 tons…

QuantumDot wrote: spacecraft skin

Good for microcraft but apparently does not scale
well with volume. Fusion-powered ships will by
necessity not be… micro 🙂

QuantumDot wrote:
planks law breakdown

Yes, I know you’re not breaking the laws of
thermodynamics 🙂

Quantum dots have great potential but are not
quite to the point where we could build a ship
around the concept… yet.