Elongation (κ)

Elongation stretches the plasma cross-section vertically for higher current and pressure. Kronos runs a strongly shaped κ = 2.56.

Symbol

κ (kappa)

Kronos value

2.56 (achieved)

Benefit

More current and pressure for a given size

Cost

Vertical instability needing active control

Elongation (κ) measures how much the plasma cross-section is stretched vertically — a tall, D-shaped plasma rather than a circle. Stretching the plasma lets a machine carry more current and hold more pressure for its size, both of which raise fusion performance.

Kronos MetroVolt runs a strongly shaped plasma at κ = 2.56. The trade is that a tall plasma is vertically unstable — it tends to drift up or down — and must be held by active feedback and passive conducting plates. The design carries a corrected vertical-control margin of 2.02 at the floor, and the shaping works together with negative triangularity and low aspect ratio to set the operating point.