Check it out: http://www.plasmas.org/fusion-alternate.htm Only three forms of fusion are viable as aneutronic: p+B11 p + Li6 D + He3 Of this D + He3 will produce high energy neutrons form a D+D side reaction so it still need some shielding and refitting. Also He3 is a very rare substance. D+He3 is though the most energy productive and is the easiest of the 3 to fuse P+Li6 produces the lest amount of energy but produces He3 as a product. So P+Li6 fusion would be used as a (breeder reactor) for D+He3 fusion P+B11 is the hardest to make but unlike D+He3 produces no high energy neutrons from a side reaction and is totally clean. Also protons and boron are the cheapest fuels to refine and mine. For space propulsion I would go with D + He3, But for power: p+B11. Though D + He3 produce twice the energy and is easier the radiation is a problem as well as the price of fuel. p+B11 would be cheaper.