Ferroplasmic infusion was a process by which the molten core of a planet was returned to a liquid state from solid. It involved injecting plasma directly into the planet's core. The effects of a successful infusion would last centuries.
In 2370, Geordi La Forge, Data, and Doctor Juliana Tainer used this procedure to restore the core of Atrea IV. (TNG: "Inheritance")
The prefix "ferro" usually denotes iron.