magnetic confinement fusion (MCF) is the approach to 📝fusion energy that holds a hot plasma in place with magnetic fields, as in tokamaks and 📝stellarators — the most developed path to a fusion power plant.
Its defining contrast is with inertial confinement fusion, which compresses a fuel capsule for nanoseconds and lets the fuel's own inertia do the confining; magnetic confinement instead holds a far more diffuse 📝plasma steadily, for seconds to hours, at temperatures above 100 million degrees Celsius. The principle exploits the plasma's charged nature: ions and electrons spiral tightly along magnetic field lines, so a properly shaped field becomes a container no material wall could be.
Closed, doughnut-shaped fields dominate the approach. The 📝Tokamak bends field lines into a torus and adds a 📝plasma current to complete the twist, while the stellarator produces the entire twisted field with shaped external coils; open and self-organized alternatives — magnetic mirrors, Z-pinches, field-reversed configurations — trade the torus's confinement performance for engineering simplicity. Progress in every case is measured by the 📝triple product of density, temperature, and confinement time, and because 📝fusion power density rises steeply with field strength, the magnetic field itself is the single most powerful lever in the approach.