Ray Field energy is a type of energy source, which acts as the primary power source of Ray Field technology, and is also a vital part of a Conduit's anatomy and internal systems. The energy was extensively studied and researched by Sebastian Wolfe, whom helped develop technology that utilizes the energy, most notable devices worth mentioning would be the Ray Sphere and Ray Field Inhibitor.
Based off the explanation in inFamous the Ray Sphere absorbs the bioelectricity - primarily the brain's neuroelectricity - from people within the blast radius of the Ray Sphere (vaporizing them). It then transforms the bioelectricity into Ray Field energy, the bulk of which is used to activate the conduit gene in the sphere's user. Excess Ray Field energy is then spread by the blast that results from activating the Ray Sphere making Ray Field energy the primary by-product of using the sphere along with anything affected by the energy itself.
Exposure to the power source can have specific (and often unpredictable) effects on living organisms. For example, an active Conduit can gain more power, while humans gain a fatal sickness from the energy's radiation field.
It is unknown if Ray Field energy existed in any natural form before experiments with the Ray Sphere began or before its completion. There may however have been a small amount of energy before the Ray Sphere, evident due to the fact that Conduits existed. Most Conduits died the moment the Ray Field Energy was Inhibited, implying that they couldn't live without its presence.