Generalized Curvilinear Coordinates in Hybrid and Electromagnetic Codes

This paper describes the elements for writing hybrid and electromagnetic plasma simulation codes in generalized curvilinear coordinates. The coordinate system is described by a table giving the three-dimensional Cartesian coordinate positions of a structured curvilinear coordinate mesh. The paper shows how to calculate the geometric coefficients of the differential operators describing the electromagnetic field and how to calculate the motion of particles across the curvilinear grid. In addition, a new algorithm for calculating the particle current sources for the electromagnetic field is described that conforms naturally to the curvilinear grid. Measures are described for checking and ensuring accuracy of the code. Extension of the methods for multiple, discontinuously joined coordinate patches is also outlined.