The most coveted material in power engineering is erudium, a high-temperature superconductor. A synthetic compound made of several rare lanthanides including erbium and dysprosium, it is the critical element in the coils used for contemporary erudium-based superconducting magnetic energy storage (ESMES). Once a superconducting erudium coil is saturated with charge, it will not decay and the magnetic energy can be stored indefinitely lest it be particularly disturbed. It can be discharged rapidly at the nanosecond scale, which is useful for the fusion ignition process.

Erudium is the foundation of z-pinch fusion reactors. A z-pinch reactor crunches and confines a working plasma across the long axis of the cylindrically shaped fusion chamber. When an electric current runs through the plasma down the center axis, the electromagnetic force will pull the plasma ions towards each other. The gas pressure of the plasma and the electrostatic force attempt to counteract this force. If the crunch provided by the jolt of high current is sufficiently strong, the plasma undergoes thermonuclear fusion, releasing net energy.

As a superb inductor, erudium is also used in many military situations where quick energy dissipation and high efficiency is needed: railguns, ion beam steering, energy banking for high-power handheld weapons, etc. In civilian use, this kind of room temperature, superconducting magnetic energy storage is applied in power grid management, emergency energy storage, maglev trains, and so on.

Erudium fabrication is complicated by the necessity for material purity. Just as in any superconducting material, it has a normal or resistive state at a hot enough temperature: heat that is often experienced during forging and manufacture, or near an active fusion reactor. Any material defect in the superconducting coil can cause a magnet quench, as can environmental heating. Great care must be taken to prevent magnet normalization, which can have some disastrous consequences, particularly at scale.

Above the critical field limit, the superconducting state of erudium is destroyed. This means that there exists a maximum charging rate for an erudium inductor per unit volume, given that the magnitude of the magnetic field determines the flux captured by the superconducting coil.

For microfusion applications whereby the volume of working plasma is small, miniaturized toroidal solenoids are used. This has the effect of reducing material costs, as erudium is made of rare, processed lanthanides and requires careful fabrication and spooling. For bigger reactors requiring larger volumes of plasma to be ignited, support structures are required for heavier coils to mitigate induced mechanical forces.

Mu-metals, supermalloys, and other structures shield sensitive electrical components from ESMES systems.