You could also approach it from a weapon’s perspective if you figured out a way to open up a hole in the reaction chamber and create a directed energy “beam” or some such through the hole. THAT would be a mighty powerful weapon.... AND it would be extremely efficient.
I suspect close to a 1 to 1 ration of energy created to destructive power (focused and directed). You could literally vaporize a target with a millisecond energy burst.
ration = ratio