okay, let’s scale this up by tesselating a spherical onion ~3m diameter with up to 60 anodes, and immersing the entire assembly in water, at the tail of the aircraft. i will bet that the capacitor bank scales sub-linearly. even if we must completely surround the reactor with shielding, i’m getting < 100 tonnes for the whole thing. that's 27..50 tonnes of water, alone; and the rest is equipment.

now i know this ignores failsafe mechanisms, which you’d likely want to do, so maybe we can split this into two reactor compartments, and place them in the shoulders of the wings. this would increase the share of the water shielding somewhat; but in the event of failures, you can run your 5 MW anodes at 10..15MW if you like.

the result is quite a massive increase in payload capacity, ~50..150 tonnes