Impact Fusion with A Segmented Rail Gun

Abstract : The rail gun offers an attractive alternative to the traveling wave rifle for the magnetic acceleration of macroscopic (0.05 g) bullets for impact fusion. In this paper we review the basic rail gun equations and indicate how energy efficiency can be designed in. We set as our preliminary goal the delivery of 1 megajoule in 10 nanoseconds, with a specific energy of 20 MJ/g (i. e. a bullet mass of 0.05 g); these values are taken from the requirements being considered for heavy-ion fusion. Using these numbers the final particle velocity is 200 km/sec. For a delivery time of 10 nanoseconds, this velocity implies that the projectile length is about 2 mm. Impact fusion is feasible because of the coincidence that a bullet with all dimensions roughly 2 mm has the required mass.