gold smoke...
@ anonymous boffin...
I'm sure there's something inert that could be used to create a suitable smoke / fog if the carbon particles would ignite. Water vapour perhaps?
As for the laser gold, the laser may be producing MJ/s worth of energy at source, but a lot is absorbed by the atmosphere between the plane and the missile. How much energy is delivered at the target 400Km away? Surely the gold plating would at least about half the effective range of the laser since it would have to be delivering nearly twice as much power as the theoretical minimum to destroy the missile. Regarding the mass of the gold, the laser gold plating is used in lots of aerospace applications, so it's probably relatively light.