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How do neutral beams heat plasma in a fusion reactor?
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fusion reactor
A tokamak is a device used in nuclear-fusion research for magnetic confinement of plasma.
In a fusion reactor, neutral beam injection is a primary method used to heat plasma to the extreme temperatures—often exceeding 100,000,000 K—required for nuclear fusion to occur.12
The process functions as follows:
- Injection: Beams of high-energy neutral atoms are injected into the plasma. Because the atoms are neutral, they are not deflected by the magnetic fields used to confine the plasma, allowing them to penetrate deep into the core.12
- Ionization: Once inside the plasma, these neutral atoms undergo collisions with existing plasma particles, causing them to become ionized.12
- Energy Transfer: Once ionized, the particles become trapped by the magnetic field. They then transfer their kinetic energy to the plasma through a process of slowing down, which effectively heats the plasma.2
When the goal is purely heating, the beams are typically injected in both directions around the torus to ensure that no net momentum is imparted to the plasma.2