Аннотация:An original algorithm was developed for ray tracing across unstructured3D grid. The resulting set of rays provides the base for the grid-characteristiccomputation of radiative energy transfer in the high temperature plasmasimulations using MPI parallel technique and grid decomposition. The algorithm isimplemented as a C++ code and incorporated in 3D magneto hydrodynamic(MHD) Eulerian code. Accurate rational calculations using integers of unlimitedrange are applied for the intersection of rays with grid elements. Tracing ofdifferent rays within a single MPI process is carried out in parallel with the use ofOpenMP threads. Acceleration and scalability of the implemented algorithms wereinvestigated including a comparison with other solvers within MHD code. Thedeveloped algorithm enables accounting the anisotropy of the radiation field incomplex multiscale 3D MHD simulations. Proposed applications are thefollowing: 1) postprocessing the results of 3D simulations (numerical pinholeimaging, estimation of the radiation output in a given direction); 2) modeling thepropagation of the laser radiation; 3) calculating the thermal radiation field on thebasis of quasi-diffusion model (improvement of the Eddington factor for thediffusion approximation).