A Conceptual 3-D Design of a Non-Destructive Two-Layer Quasi-Force-Free Magnet for Megagauss Field Generation

Abstract

On the basis of prior research, a conceptual three-dimensional (3-D) configuration of a non-destructive two-layer magnet capable of generating megagauss-level magnetic field was developed. The design is based on the concept of quasi-force-free coils, in which conductors have a special shape tailored to minimize mechanical stresses caused by electromagnetic forces. Multivariate multi-physical finite element simulations were used as the main tool for developing the presented configuration. The magnetic system was analyzed for its ability to withstand Lorentz forces, and calculations demonstrate that the design ensures maximum stresses in the windings significantly less than the magnetic pressure of the generated field. That reveals a possibility of achieving a megagauss field in the system, provided that certain requirements are met for the used materials. Such requirements were formulated and are realistic (e.g., ultimate strength about 1 GPa for the conductors). Estimation of the possible pulse duration limited by the admissible temperature of the conductors allowed us to perform a transient electromagnetic analysis. Results highlight the importance of mitigating the skin effect in the system, and possible ways for that are proposed. The energy of the magnetic field in the proposed system is estimated to be about 1 MJ, which is significantly less than the energy in magnets of more conventional configurations with similar bore diameters.