Self-Heating Fraction at Q 3.076

The fraction of plasma heating supplied by fusion alphas rises with gain; at Q_sci 3.076 it is substantial but the plasma still needs external heating.

How self-heated is Q 3.076

The self-heating fraction is the share of total plasma heating that comes from confined fusion alphas rather than from external systems. It rises directly with gain: as Q_sci increases, more of the heating is internal. At Q_sci 3.076 the alpha contribution is a substantial fraction of the heating, which is what distinguishes a genuine burning-plasma regime from a purely externally heated one.

This is a physically important threshold. A plasma with significant alpha self-heating exhibits coupling between the fusion rate, the temperature, and the heating that a low-gain plasma does not. That coupling brings both benefit — the plasma helps sustain itself — and new control challenges, because the self-heating responds to and reinforces changes in the plasma state.

Below ignition, on purpose

Hyperion is not designed to ignite. External heating remains part of the power balance at Q 3.076, which keeps the plasma controllable and the operating point robust. Ignition would remove the external handle used to steer the burn. For a foundry that must run steadily and safely, a strongly self-heated but externally controlled plasma is the intended regime, and the exact self-heating fraction is a design-and-simulation output.

• Self-heating fraction rises with Q_sci
• At Q 3.076 the plasma is substantially, not fully, self-heated
• Staying below ignition preserves external control of the burn

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. No hardware net-gain is claimed before FOAK.