Stellarator

A stellarator confines plasma with twisted external coils and no plasma current — disruption-free but complex. Kronos chose the tokamak path.

Confinement

Twisted external coils, no net plasma current

Upside

No current-driven disruptions; steady-state

Downside

Complex 3D coils; historically lower confinement

Kronos choice

Tokamak (higher performance density)

A stellarator is a magnetic-confinement device that produces its entire confining field from intricately shaped external coils, with no need for a large current flowing in the plasma. That is its great advantage: without a plasma current there are no current-driven disruptions, and the machine runs naturally in steady state.

The trade is complexity — the coils are three-dimensional and hard to build — and, historically, lower confinement than a tokamak of similar size. Kronos chose the tokamak path for its higher performance density, and instead engineers around the disruption problem with negative triangularity, robust vertical control, and a resistive-wall-mode feedback system.