Tokamak

A tokamak confines fusion plasma in a magnetic torus. Kronos MetroVolt is a high-field, negative-triangularity spherical tokamak.

Origin

Soviet acronym for 'toroidal chamber with magnetic coils'

Kronos class

Spherical tokamak, aspect ratio 2.0

Confining field

B₀ = 6.0 T on axis, 24.6 T peak conductor

Shape

κ = 2.56, δ = −0.30

A tokamak is the most developed approach to magnetic-confinement fusion: it holds a hot plasma inside a doughnut-shaped (toroidal) magnetic bottle. Powerful external coils produce a toroidal field, while a current flowing through the plasma itself adds a poloidal field; together they twist into helical field lines that keep the charged particles from drifting into the wall.

Kronos MetroVolt is a spherical tokamak — a low-aspect-ratio variant — running at high field with REBCO magnets, strong shaping (elongation κ = 2.56), and negative triangularity. Those choices are what let a compact tokamak target gigawatt-class fusion power on a low-neutron D–³He fuel.