[AR] Re: Alternative propulsion was: Flying to Orbit with Hydrogen?
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: "(AR) ocket List" <arocket@xxxxxxxxxxxxx>
- Date: Thu, 26 Dec 2019 00:08:58 -0500 (EST)
On Wed, 25 Dec 2019, Charlie Garcia wrote:
As an aside, would torch-ship style fusion powered engines have the same
radiation concerns that Project Orion or NERVA would? Fusion produces mostly
non-radioactive products, would neutron irradiation still cause problems?
Even the allegedly-aneutronic fusion reactions do produce some neutrons,
alas, and those reactions are mostly so difficult to ignite that even
long-term feasibility is quite uncertain. The easy fusion reactions put
out a good fraction of their total energy in neutrons (much more than
fission). There's less *direct* production of radioactive trash, but the
problem does not entirely go away.
The on-board radiation environment is also really problematic, between
neutrons, gamma rays, and bremsstrahlung X-rays. Not just for the
familiar radiation effects on electronics, payload, crew, etc., but
because a really muscular fusion engine will put out enough to make
radiation *heating* a big problem for nearby structure etc. Nuclear
propulsion could really use a breakthrough in radiation shielding.
Henry
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