The application of Kiuttu´s formulation to study coaxial flux compression generators

A class of flux compression generators (FCGs) is based on the compression of the cross-sectional area of a coaxial geometry where the current flows along the outer conductor and returns through the inner conductor¹. This compression causes an increase in current since magnetic flux must be conserved. Kiuttu´s inductive electric field formulation is a powerful tool for the conceptual design of coaxial FCGs². The usefulness of this formulation is demonstrated in this paper for a simplified geometry using a finite element partial differential equation solver, FlexPDE™, for calculation of the inductive electric field. A time varying applied current or a moving surface creates the non-conservative electric field. Losses due to diffusion of magnetic flux into conducting surfaces can also be accounted for and modeled in this setting. This analytical-computational approach serves as an important step in validating the MHD portion of the complex multi-physics parallel LLNL code, ALE3D. The non-intuitive boundary conditions involved in solving the otherwise straightforward partial differential equations are described in detail and illustrated in a simple model. The physical parameters used in the simulations are not based on a specific design.