A moving finite element model of the tokamak scrapeoff layer

Most numerical simulations of the tokamak scrapeoff layer use a mapping to flux coordinates and a piecewise equidistributed grid in those coordinates to resolve multiple length scales and anisotropy. We have developed an alternative numerical method using simple cylindrical coordinates with a complex adaptive grid scheme, based on an unstructured grid of triangles which move adaptively, aligning themselves with the magnetic field and concentrating in regions of sharp gradients. (orig.)