Optimization of target irradiated by light ion beam

A proposal is given here for a method to optimize the cryogenic hollow shell target which consists of the three layers of Pb, Al and DT fuel. The target is named as “Niu target” and does a cannon type of implosion. By using a model that the ion beam deposits its energy instantaneously in the Al pusher in the target and the pusher expands adiabatically and homogeneously, the final implosion velosity UDT of the fuel can be obtained as a function of the beam energy Eb, the target radius rAl, the fuel radius rDT, the thickness δpb of the Pb layer, the thickness δAl of the Al layer and the rate CAl of beam energy deposition in the Al layer. Through the empirical laws obtained by simulations, the ion temperature Ti and the fusion parameter ρR of the fuel after the fuel collision at the target center can be derived as functions of the preheat temperature TO of the fuel, the effective mass M of the imploding materials (the fuel mass added by the pusher mass), the fuel mass MDT and UDT. Through Ti and ρR, the average reaction rate Y of the fuel is estimated. Thus the output thermal energy Ef can be obtained as functions of the particle energy eb, Eb, rAl, rDT, TO and CAl (hence δPb and δAl). The pellet radius must be decided by considering the instabilities in the pellet and is chosen as rAl=6mm. Now we choose Eb=6MJ, TO=1000K and let us optimize Ef with respect to rDT, eb and CAl. At last we have rDT=3.2mm (MDT=2.37×10⁻⁵kg), eb=5.1MeV, and CAl=87% (δPb=20.5 µm and δAl=156 µm) as optimu- values, and we obtain the fusion output energy of Ef=2.46GJ.