In article ,
Charles Talleyrand wrote:
What's the current state of the art in ion engines? How well
do they do, and when one adds solar panels (or some other energy source)
and such to the mix, what's the thrust/weight ratio?

Pretty poor. :-) It's difficult to find useful numbers, because there
are so many variables. The power-conditioning electronics behind the
engine often considerably outweigh the engine itself, and then there
are the solar arrays...

Deep Space 1's engine hardware (including electronics) was 48 kg, giving
92 mN of thrust and 30 km/s exhaust velocity, using 3 mg/s of xenon, at
full power (2.5 kW, which the spacecraft in fact couldn't quite deliver).
You can probably do better than that -- it was a conservative design.

Solar-array masses depend on how optimistic you are (and how careful you
are about accounting for *all* support hardware etc. -- inflated numbers
counting only part of the hardware are common). For the entire system,
40 W/kg is routine, 100 W/kg is aggressive and experimental, and really
optimistic people think several hundred W/kg could be had with determined
use of new technologies.

Ion engines are the current winner in the very-low-acceleration game, right?

Depends on what you mean by "winner". :-) They're the obvious choice right
now if you have lots of power, don't need much thrust, and absolutely need
high Isp (i.e., minimum propellant consumption). They lose badly if you
have limited power or need significant acceleration.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |