Oriented Cone Fast Ignition In Fundamental Physics

The fast ignition concept using ultra-intense laser pulses is now being explored. FI scheme separates the laser into two systems: one for implosion and the other for heating the imploded fuel core. Since the laser energy required just for implosion is much smaller than that for the central ignition scheme.The realization of this concept is challenging since the core is hidden under a plasma corona with a long scale length, which is opaque to the laser pulse. To overcome this problem, an alternative to laser pre pulse techniques is the use of a reentrant cone to block the formation of a plasma atmosphere in front of he core. This allows the ignition laser a clear path and close approach to the assembled core and well-defined surface at which to create electrons. The details of the interaction between the laser and reentrant cone is presently unclear.This work is organized in five sections. At first we introduce briefly the concepts of ICF and principles of Fast ignition. In section II ,we introduce the setup of the method for fast ignition and latest research about the hollow cone shell target.In section III, we introduce the absorption mechanisms in plasma. These mechanisms accelerate electrons into high-density plasmas. In section IV, we introduce the experiment "The impact of Au cone on forward hot electrons". The characteristics of the forward hot electrons produced by 20 TW p-polarized Pico second laser-plasma interactions are studied with Au cone-targets and Au foil targets. We measure the electron energy spectra and angular distribution of Au cone target, compares it to the result about foil target. The result shows that, the hot electron numerate of 30° cone-target is larger than foil target condition in the range of 2～2.5MeV. From the divergence angle of the hot electrons, the energy flux of the electrons in 30° cone-target can be significantly higher than that in a foil target. It shows that the cone target could guide and focus the ignition impulse. The hot electron dose of 15° cone-target was less than foil target. Mostly cause is impact of pre plasmas. Prep-plasmas are formed by yawp front pulse. It reduced the laser power density and absorbed the hot electrons.In Section V, it made a summary of article and depicts subsequent study.