Re: Deutrium formation
What you would want to look at are the nuclear crossections of hydrogen for absorbing neutrons (not protons). I believe that, as Nick implied, that is a very small number requiring a large neutron flux. However, since free neutrons decay to protons with about a 15 minute half life, few solar neutrons would be available at Mars anyway. Few neutrons released through DT reactions on the sun, that make it to the surface, will survive to Mars.
Dave M