Given the not terribly successful attempts to use fission reactors in aircraft I did wonder about this. Apparently Helion's approach is "mostly aneutronic fusio

Given the not terribly successful attempts to use fission reactors in aircraft I did wonder about this. Apparently Helion's approach is "mostly aneutronic fusion" - still means that 5% of power output as fast neutrons - which I suspect is probably too much to shield from in an aircraft (mind you I am not a nuclear or aircraft engineer so what do I know!). Thinking about the fictional Helios in the excellent For All Mankind does make me wonder if it might work in a spacecraft!