Plasma Density & Fuelling
Fusion power rises with the square of density, so running dense is valuable. Kronos operates above the Greenwald limit, sustained by careful fuelling.
- Why density
- Fusion power ∝ density²
- Kronos density
- n̄_e = 2.2 × 10²⁰ m⁻³ (Mode D)
- Greenwald fraction
- f_GW = 1.33 (above the nominal limit)
- Sustained by
- Gas puffing + pellet fuelling
Because fusion power scales with the square of plasma density, running dense is one of the most direct ways to raise output. But density is bounded: push too hard and the plasma approaches the Greenwald limit, where disruptions become likely in conventional plasmas.
Kronos MetroVolt runs at a line-averaged density of n̄_e = 2.2 × 10²⁰ m⁻³ at the frozen Mode-D point — a Greenwald fraction of 1.33, well above the nominal limit — which the negative-triangularity edge makes non-disruptively accessible (NT plasmas sustain up to 1.8× Greenwald). Holding that density in steady state takes active fuelling: edge gas puffing plus deep pellet injection to keep the core supplied, balanced against exhaust and ash removal.