The physics of DT ignition in small fusion targets

Ignition of sub-milligram fusion targets is critically dependent on DT temperature, density, radius, radiation temperature, implosion velocity, and other parameters that characterize the target and its implosion. This paper discusses the interplay of such major physical processes as bremsstrahlung, Compton scattering, DT fusion, hydrodynamics, and thermal conduction during the implosion and especially near turn-around where the potential for ignition or failure most critically depends on the small differences between large rates of energy loss and gain. The phase plane analysis presented here proves to be most advantageous in understanding the DT ignition problem. Four examples are discussed in order to illustrate the interplay of the various physical processes. (author)