H-mode (High-Confinement Mode)

A spontaneous transition to roughly doubled confinement, standard in modern tokamaks.

Above a power threshold, tokamak plasmas jump into a high-confinement regime — H-mode — in which an edge transport barrier roughly doubles the energy confinement time relative to L-mode. The confinement multiplier H₉₈ = 1 denotes standard H-mode performance.

HYPERION's confinement target of H₉₈ = 1.0 places it squarely at established H-mode performance rather than beyond it — a deliberately unaggressive assumption.