The role of fast electron energy transfer in the problem of shock ignition of laser thermonuclear target

The role of energy transfer by fast electrons, which is responsible for the positive effect of increasing the ablative pressure and the negative effect of preheating, on the implosion and thermonuclear gain of the target designed for shock ignition is investigated in comparison with the target designed for traditional spark ignition. On the base of one-dimensional hydrodynamic simulations with kinetic description of fast electron transfer it is shown, that depending on the characteristics of fast electron flux, in shock ignition target are manifested to varying degree both effects the positive and negative ones. This is a distinguishing feature of a shock ignition target compared to a traditional spark ignition target, in which only the negative effect of fast electron energy transfer takes place. In a shock ignition target up to temperatures of 50-60 keV, the positive effect is dominant and provides high gain. With an increase in the fast electron temperature, the role of the negative preheating effect increases, that ultimately leads to the ignition failure as temperature exceeding 90-100 keV.