Kinetic effects on the electron thermal transport in ignition target design

The preheating is one of the most critical issues in laser fusion, because it causes significant reduction of volume compression. The nonlocal heat transport by the high energy tail electrons in ablative plasmas is found to be essential for the preheating under high intensity laser irradiation. In such a situation, electron heat transport is described by the Fokker‐Planck (FP) equation in a fluid implosion code, since the Spitzer‐Harm (SH) thermal conduction model is not applicable. The numerical simulations of the implosion have been carried out for the fast (high entropy) implosion mode in which the implosion velocity is as high as 6×107cm/sec in order to reduce the required laser energy for ignition. The control of preheating is essentially important for this type of implosion mode. The isentrope of an imploding shell is evaluated to see the preheating level. It is found in the fast implosion mode that the isentrope in the FP simulation code is higher by 2 to 4 times than that in the flux limited SH si...