Short Characteristics Radiation Transport in SPECT3D

Short Characteristics (SC) is a method of calculating radiation transport in non-LTE plasmas wherin the transport equation is solved along rays through a given number of nearest-neighboring cells. At the cost of accuracy, SC can save immensely on computation time compared to Long Characteristics (LC), where transport is calculated all the way to the plasma edges for each plasma zone. This is especially important for large grids where LC becomes prohibitively expensive. SPECT3D is a collisional-radiative spectral analysis package which can utilize SC and LC for radiation transport in 1D, 2D and 3D geometries. Here we present improvements to SC modeling in SPECT3D, including a new angle grid model for focusing the grid of transport rays in order to resolve known radiation hotspots.