I personally believe that the pulsed/inertial would be the fusion, be it energy generation or space engine (after all the only net positive artificial fusion de

I personally believe that the pulsed/inertial would be the fusion, be it energy generation or space engine (after all the only net positive artificial fusion device so far - thermonuclear bomb - is "pulsed", and so we have only a matter of engineering to scale it down :). My bet though would be on something like Sandia Z-machine or on laser (as we've had remarkable laser efficiency improvements) as they clearly create fusion conditions (and much closer to the bomb confinement wise) and burn significant amounts of fuel (thus allowing for typical established ways of energy generation) than for example Helion where the plasma clouds don't carry much fuel and thus can't produce significant amounts of energy.