The Fusion Triple Product
The triple product of density, temperature, and confinement time is the single figure of merit for how close a plasma is to net fusion.
- Definition
- n · T · τ_E
- Meaning
- How close a plasma is to net-energy conditions
- Density
- n̄_e = 1.9 × 10²⁰ m⁻³
- Temperature
- T_i0 = 65–70 keV
The fusion triple product multiplies three quantities a plasma must have simultaneously: density (n), temperature (T), and energy confinement time (τ_E). Their product is the single most useful figure of merit in fusion — the higher it is, the closer the plasma sits to the Lawson condition for net energy.
It encodes a real trade-off: a designer can reach a target triple product with more density, more temperature, or better confinement, and different machines make different bargains. Kronos MetroVolt combines high density (n̄_e = 1.9 × 10²⁰ m⁻³, running above the Greenwald limit), high ion temperature (65–70 keV), and the confinement its negative-triangularity shape is designed to deliver — each an ingredient of the triple product the design must hit.