Burner Deuterium-Helium-3 Fuel Cycle
The burner fuses deuterium with helium-3, a reaction that releases its energy mostly as charged particles.
The fuel and its reaction
The burner runs on deuterium and helium-3. When they fuse, they produce a proton and a helium-4 nucleus, releasing about 18.3 MeV of energy carried entirely by charged particles. This is the reaction that makes direct energy conversion and low neutron output possible.
Advantages of the fuel
- The main reaction produces no neutron, so most energy is in charged particles.
- Charged-particle energy can be captured directly by the converter.
- Low neutron output means less activation and lighter shielding, the 5.44 percent design fraction.
The challenges
Deuterium-helium-3 is much harder to burn than deuterium-tritium: it needs higher temperatures and better confinement to reach useful reaction rates, which is part of why the burner uses such extreme plug fields. Deuterium will also fuse with itself, and those side reactions are the source of the residual neutrons. And helium-3 is genuinely scarce, which is a real constraint on the fuel supply rather than an afterthought.
Why a mirror suits it
A tandem mirror pairs naturally with this fuel. The high fields needed for confinement also enable the high mirror ratio, and the open linear geometry sends escaping charged particles straight into a direct converter. The fuel and the machine architecture reinforce each other: the charged-particle output is only useful because the geometry can catch it.
In the model
The fuel cycle is represented by the fueling and exhaust connections at the central cell and end tanks rather than a single part. See the neutron fraction and shielding and the direct-energy converter that the fuel choice enables.