Viewa - A computer code for the calculation of anisotropic radiative intensities on a spherical capsule within a cylindrical hohlraum

This paper presents a numerical method for calculating anisotropic radiative intensities on a spherical capsule within a cylindrical hohlraum. The combination of capsule and hohlraum is the typical configuration in the indirectly driven inertial confinement fusion (ICF). The hohlraum is irradiated by lasers and thus generates an anisotropic radiative field around the capsule. The radiative energy flux along the hohlraum inner surface is firstly computed by utilizing the conventional view factor formulation. Anisotropic radiative intensities on the capsule are then obtained from the Lambertian approximation. A numerical example calibrated by experimental radiation temperature is further provided to demonstrate the anisotropy of radiative intensities in ICF. Program summary Program Title: Viewa CPC Library link to program files: https://doi.org/10.17632/hngb5z2m2x.1 Licensing provisions: GPLv3 Programming language: M language Nature of problem: In order to assess the radiative drive symmetry in the indirectly driven ICF, it is necessary to compute radiative intensities on the capsule. Moreover, the capsule-only simulation of the indirectly driven ICF with the radiation transport equation requires radiative intensities on the capsule as boundary conditions. However, it is difficult to calculate the radiative intensity at a given location on the capsule in a given direction. Solution method: We firstly compute the radiative energy flux along the hohlraum inner surface by using the view factor method. The radiative intensities on the capsule are then calculated from the Lambertian approximation. Additional comments including restrictions and unusual features: Due to the low density of the filling gas between the capsule and the hohlraum, the radiative intensity slightly attenuates when propagating from the hohlraum inner surface to the capsule surface. And the view factor method is computationally efficient. Hence the introduced method can specify radiative intensities accurately and efficiently. But two dimensional rotational symmetry is assumed in this paper, and some parameters need to be calibrated by experimental radiation temperature.