But won't that just effectively make it a nuclear thermal rocket (if a rather contrived one)? Wouldn't the 'additional thrust' from exhausting coolant hydrogen make up most of the thrust.
Quote from: as58 on 04/21/2017 06:49 amBut won't that just effectively make it a nuclear thermal rocket (if a rather contrived one)? Wouldn't the 'additional thrust' from exhausting coolant hydrogen make up most of the thrust.I guess it depends on how much hydrogen you have to bleed through to cool the rocket. If it is very little, it will probably not matter much.
Regardless of how you try to arrange things, if you want the hydrogen to carry away the fission energy, it has to vastly outmass the fissile fuel. All the moreso if it has to do so at temperatures that won't destroy cooling channels.
Quote from: Rei on 04/21/2017 03:10 pmRegardless of how you try to arrange things, if you want the hydrogen to carry away the fission energy, it has to vastly outmass the fissile fuel. All the moreso if it has to do so at temperatures that won't destroy cooling channels.I am not so sure about that. IIRC most of the VASIMIR rockets are bleeding small amounts of hydrogen through the cooling channels after the rocket engine has been turned off to keep the engine cool enough.
Good points. Might need the hydrogen itself to act as the neutron reflector, or simply have a big enough core that no reflector is needed. You still have to cool the coils, but the neutrons could mostly just fly out into space. Additional hydrogen could be added to increase thrust, but not so much that the plasma state is unable to be maintained.These requirements may mean the engine would have to be HUGE.
There is an article today about Chinese researchers having developed a neutron source that is 100 fold better than current state of the art and they believe they can make it a one thousand fold increase:https://phys.org/news/2017-04-laser-technique-neutron-yield.html
I wasn't thinking of moderating the neutrons. I was thinking a fast neutron reactor.