ANALYTIC MODEL FOR THE DYNAMICS OF FAST IGNITION

A relatively simple model for the dynamics of fast ignitors is present ed. The model describes the processes taking place when a precompresse d fuel is heated by a particle beam (ions or electrons) characterized by its range R, and the focal spot and intensity of the beam. As a res ult, the ignition conditions are calculated in terms of such parameter s and of the fuel density. The model provides scaling laws for the ign ition energy and for the beam intensity in which the dependence on the particles range is included. Besides, it gives a simple interpretatio n of reported simulations and explains the apparent discrepancies betw een them and previous analytic estimations. The importance of using pa rticles with R less than or equal to 0.3 g/cm(2) turns out to be from the dependence of the ignition energy and the target gain on the range . (C) 1998 American Institute of Physics. [S1070-664X(98)01907-7].