An ion beam target for 3 GJ fusion output

Abstract

If the burn fraction of fuel in a cryogenic target of one-shell three-layers (lead tamper, aluminum pusher and solid DT) is assumed to be 35% ( T i = 4 keV and ρR = 4 g/cm 2), the mass of fuel in a target must be 23 mg. An optimum condition for the target is that the rate of beam energy deposition in the pusher layer is 85%. For such an optimized target the ion beam energy and power radiating on the target are required to be 6 MJ and 200 TW/cm 2, respectively, in order to realize T i = 4 keV and ρR = 4 g/cm 2 for the fuel. A spherical hollow-shell target forms a converging nozzle for the fuel and the fuel is compressed in a supersonic region. When the implosion velocity is u = 3 × 10 5 m/s at r = 5.5 mm, the Mach number of the fuel is M = 12 and in the supersonic region the fuel is compressed to ρ = 269 ρ solid = 51.2 g/cm 3 at r = 0.27 mm, and in the subsonic region to ρ = 3.51 × 10 4 ρ solid = 6.67 × 10 3 g/cm 3 at r = 10 −2 mm.