Energy deposition of fast electrons in fast ignition

Energy deposition of ultra-intense laser driven fast electrons into the highly compressed fuel core plasmas is of great importance in assessing the overall coupling efficiency in fast ignition scheme. In this paper, a relativistic kinetic model is established based on fundamental principles of plasma collisions to explore the energy deposition process. The relativistic Fokker-Planck equation is derived, including both the binary collision and the contribution from plasma collective response. It is formulated in a differential form with the help of analogous Rosenbluth potentials. Its explicit expression in three-dimensional momentum space is obtained via spherical harmonics expansion method, in which only simple differentiations and integrations are involved. Corresponding numerical algorithms are developed as well as the kinetic code. Typical fast ignition physical cases are presented, and it is used to make a preliminary analysis for the coming FI experiments in Shengguang Ⅱ laser facility.