Domain overview
What plasma physics decides in a fusion reactor
Original Fusenergy explanation, framed against public technical references. Educational, not engineering or investment advice.
Plasma physics sets the ceiling on every fusion concept. To release net energy, a deuterium–tritium plasma must reach roughly 100–150 million kelvin (about 10–15 keV) and hold enough particle density for long enough that self-heating outpaces losses. That balance is captured by the fusion triple product — density × temperature × energy-confinement time — and almost every topic in this domain is really a question about how to raise one term without collapsing the others.
The hard part is that a hot plasma leaks. Turbulence driven by temperature and density gradients transports heat outward far faster than simple collisional theory predicts, so confinement is an experimental science as much as a theoretical one. Stability limits — the beta limit on plasma pressure, edge-localized modes at the boundary, and impurity accumulation that radiates energy away — each cap how hard a device can be pushed before performance saturates or the discharge ends.
In a burning plasma the 3.5 MeV alpha particles from D–T fusion stay confined and heat the fuel themselves, which is the transition every reactor concept is chasing. The ten topics here — from Debye shielding and collisionality through transport barriers, radiative cooling, and burning-plasma equilibrium — are examined across all six lenses so you can separate a genuine confinement result from a favourable operating point that will not scale.
Triple product and self-heating
Ignition-relevant conditions require temperature, density, and confinement time together. Alpha heating becoming the dominant power input marks the shift from an externally heated experiment to a burning plasma.
Transport and turbulence
Cross-field heat transport is dominated by micro-turbulence, not simple collisions. Transport barriers (H-mode pedestals, internal barriers) are the practical levers that raise confinement in real devices.
Stability limits
Beta limits on pressure, edge-localized modes, and impurity radiation each bound how hard a plasma can be driven. Understanding them is how you tell a stable operating scenario from a fragile one.