Neutral-Beam Injection

Neutral beams fire energetic neutral atoms into the plasma to heat it, drive current, and fuel the core beyond what the solenoid can sustain.

Heating with a beam

Neutral-beam injection (NBI) accelerates ions to high energy, neutralizes them so they can cross the confining magnetic field, and fires them into the plasma. Once inside, they re-ionize and transfer their energy to the plasma through collisions, heating it toward fusion conditions. NBI is one of the two main auxiliary heating systems for Hyperion, alongside RF.

Three jobs at once

A neutral beam does more than heat. Injected at an angle, it drives plasma current, contributing to the non-inductive drive that sustains 9.66 MA after the solenoid flux is spent. It also fuels the core by delivering fresh deuterium or tritium atoms deep inside the plasma. And the fast ions it creates can influence stability. Beam geometry and energy are chosen to balance these roles.

Design considerations

Beams enter through vessel ports, and every port is a gap in the breeding blanket, a neutron loss that competes with the tritium breeding ratio. Beam ducts must be shielded and routed to minimize that penalty. Injection power, energy, and aiming are set in simulation to reach the required heating and current drive while limiting the impact on breeding coverage. This coupling between heating access and breeding is a recurring theme in the compact design.

• Injects energetic neutrals to heat the core plasma
• Also drives current and fuels the plasma
• Beam ports compete with breeding-blanket coverage

This page describes a design and simulation study, not a built machine. Construction begins Q2 2027; first-of-a-kind first tritium is targeted near 2030.