Summary of UNM work on edge plasma modelling

The B2 two dimensional edge plasma code has found widespread application in modelling scrape-off layer and divertor plasma conditions for ITER and CIT (BPX). The transport physics in B2 consists of the so-called standard model that employs 2D Braginskii equations for the background plasma, anomalous cross-field transport coefficients, and classical along-field transport coefficients computed in the straight cylinder approximation. Although the code displays acceptable convergence characteristics for the class of problems of interest in ITER and CIT applications, it is remarkably resistant to improvements in the physics model. That is, extensions to including the symmetry breaking drift flows and wall or divertor plate generated impurity species in the code have not met with success - satisfactory solution convergence has not been achieved in various test problems. Given that the drift flows have been identified as being an important component of any fluid model that attempts to reconcile computational results with experimental observations and that control of impurities is vitally important in present and subsequent generations of high power machines, successful numerical models of edge plasmas must be clearly robust enough to handle a significantly expanded physical model