The Main Fusion Reactions

D–T, D–D, D–³He, and p–¹¹B are the fusion reactions that matter for power. Kronos's staged path runs down this list toward lower neutron output.

D–T

Easiest to ignite; ~80% neutron energy

D–D

Breeds ³He and tritium; moderate neutrons

D–³He

Low-neutron; charged-particle-rich (Kronos baseline)

p–¹¹B

Aneutronic; hardest (gated endpoint)

Only a handful of fusion reactions are practical for power, and they trade ease of ignition against neutron output:

• D–T (deuterium–tritium) — the easiest to ignite, but ~80% of its energy comes out as neutrons.
• D–D (deuterium–deuterium) — breeds ³He and tritium; moderate neutrons.
• D–³He (deuterium–helium-3) — low-neutron and charged-particle-rich; the Kronos commercial baseline.
• p–¹¹B (proton–boron-11) — truly aneutronic, but the hardest to achieve.

Kronos MetroVolt's staged fuel cycle effectively walks down this list — from a D–T commissioning stage, through D-rich and ³He-rich D–³He operation, toward the p–¹¹B endpoint — trading increasing difficulty for decreasing neutron output at each step.