A PARTICLE MODEL ON AN UNSTRUCTURED MESH

We describe a particle in the cell scheme which incorporates finite el ements in space and finite difference in time to follow the trajectori es of particles in their self consistent fields. As such the model exp loits the power of finite element techniques to better investigate the rich physics embedded in the particle or kinetic models. A brief desc ription of the foundations of the hybrid model of kinetic ions and mas s-less fluid electrons is first presented, followed by a brief summary of linear finite elements on triangles with relevance to the particle modeling. The particle trace method on triangular elements, particle to node density assignment, node to particle response, the scheme algo rithm, numerical stability, and finally tests of the code via eigenmod e analysis and comparison with the analytic theory and the structured simulation results are presented. The version presented here is a 2 1/ 2-dimensional one.