D-3He Reaction Physics

D-3He releases 18.35 MeV as a proton and an alpha, but its cross-section peaks at higher temperature than D-T, driving the burner's demanding plasma conditions.

The reaction

Deuterium fuses with helium-3 to produce a 14.68 MeV proton and a 3.67 MeV helium-4 nucleus — 18.35 MeV total, all in charged particles. No neutron is produced by the primary channel. That charged-particle output is the physical basis for direct energy conversion and for the burner's light shielding.

Why it runs hot

The D-3He cross-section peaks at a much higher ion temperature than D-T — tens of keV higher. Reaching a useful reaction rate demands high ion temperature, high density, and good confinement simultaneously. This is why the burner needs the full tandem-mirror apparatus: strong 26.49 T plugs, an ambipolar potential, and intense beam and RF heating. It is a harder plasma than a D-T machine, deliberately chosen for its clean output.

Bremsstrahlung matters more here

• High electron temperature radiates X-rays (bremsstrahlung), a real power drain
• 3He is doubly charged, raising radiation relative to a hydrogenic fuel
• Confinement must beat radiation losses for net gain — an honest open question
• Keeping impurities out keeps radiation down — see diagnostics and control

The high temperature and radiation sensitivity are why the burner is presented as a design and simulation study with a test unit around 2032, not as demonstrated hardware. The physics is well understood; achieving and holding the required conditions in a real machine is exactly what the test program is meant to establish.