They suggest a living and working module torus providing 40 men with 140,000 cubic feet of habitable space. The torus serves well for magnetic field generation and can be spun for artificial gravity.
The magnetic field is produced by one-inch-diameter metal-alloy tubing wound around the torus. Liquid helium flows through the tubing to reduce its temperature so it becomes superconducting (that is, a highly efficient electrical conductor).
When electricity is applied, the tubing produces a magnetic field in the same manner as the copper wire wound inside an electric motor. Englesson and Murphy propose to launch their spacecraft in 33-foot-diameter segments (the maximum diameter a Saturn V rocket is capable of launching), then assemble it in LEO.
Each 20-foot-long segment contains independent liquid-helium cooling and pumping systems and twin tubing loops.
The complete Englesson-Murphy magnetic shield system weighs 1900 tons.