Colaïtis A, Duchateau G, Nicolaï P, Tikhonchuk V
Université de Bordeaux 1, CNRS, CEA, Centre Lasers Intenses et Applications, UMR No. 5107, 351 Cours de la Libération, 33400 Talence, France.
Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Mar;89(3):033101. doi: 10.1103/PhysRevE.89.033101. Epub 2014 Mar 3.
This paper deals with the computation of laser beam intensity in large-scale radiative hydrocodes applied to the modeling of nonlinear laser-plasma interactions (LPIs) in inertial confinement fusion (ICF). The paraxial complex geometrical optics (PCGO) is adapted for light waves in an inhomogeneous medium and modified to include the inverse bremsstrahlung absorption and the ponderomotive force. This thick-ray model is compared to the standard ray-tracing (RT) approach, both in the chic code. The PCGO model leads to different power deposition patterns and better diffraction modeling compared to standard RT codes. The intensity-reconstruction technique used in RT codes to model nonlinear LPI leads to artificial filamentation and fails to reproduce realistic ponderomotive self-focusing distances, intensity amplifications, and density channel depletions, whereas PCGO succeeds. Bundles of Gaussian thick rays can be used to model realistic non-Gaussian ICF beams. The PCGO approach is expected to improve the accuracy of ICF simulations and serve as a basis to implement diverse LPI effects in large-scale hydrocodes.
本文探讨了应用于惯性约束聚变（ICF）中非线性激光 - 等离子体相互作用（LPI）建模的大规模辐射流体力学程序中激光束强度的计算。傍轴复几何光学（PCGO）适用于非均匀介质中的光波，并进行了修改以纳入轫致辐射逆吸收和有质动力。在chic程序中，将这种厚射线模型与标准光线追踪（RT）方法进行了比较。与标准RT代码相比，PCGO模型导致不同的功率沉积模式，并具有更好的衍射建模。RT代码中用于模拟非线性LPI的强度重建技术会导致人为的丝状化，并且无法再现实际的有质动力自聚焦距离、强度放大和密度通道耗尽，而PCGO则成功做到了。高斯厚射线束可用于对实际的非高斯ICF光束进行建模。预计PCGO方法将提高ICF模拟的准确性，并作为在大规模流体力学程序中实现各种LPI效应的基础。
