Neutral Beam Injection (NBI)
A primary plasma heating and current drive method where high-energy neutral atom beams are injected into a magnetic confinement fusion reactor.
Governing formula
P_NBI = I_beam × V_acceleration
SI unit
MW (Beam Power) & keV (Particle Energy ~100–1000 keV)
In depth
High-energy ions (deuterium or hydrogen) are accelerated to 100–1000 keV, neutralized in a gas cell, and injected across tokamak magnetic fields. Trapped by charge exchange collisions inside the core, they transfer kinetic energy to plasma ions via collisions.
Examples in the real world
33 MW Neutral Beam Injection systems heating ITER fusion plasma to 150 million °C.