An analytical model is developed to describe the parameters of the fuel and the pusher at peak compression when a two‐layer spherical shell target is imploded by a single pressure pulse. The entropy generated by shock waves during the implosion is calculated and an approximate description of the process of central hot spot formation is given. The stagnation stage of a compressible shell is described and scaling laws for the final stage are found. Comparisons with available simulation data are presented and the effect of the thermal conduction in the formation of the central spark is discussed.