Comparison and optimization of lift and drag forces on vehicles levitated by eddy current repulsion for various null and normal flux magnets with one or two tracks

Lift and drag forces are compared for various null and normal flux superconducting magnet configurations where each coil consists of a pair of infinitely long parallel wires separated by a fixed distance. The nullflux configuration has a minimum in the drag to lift ratio for a particular value of I
²
/W (I=magnet current, W=vehicle weight) when the vehicle cruises freely at constant speed. This calculation takes into account losses due to non-uniform eddy-current density distribution in the solid track. Results indicate that the null-flux configuration is the most efficient design, followed by the normal-flux, single track configuration. All other schemes are less efficient for a thin track configuration. A general method is outlined for calculating the zero-torque case.