High-confinement mode

High-confinement mode, or H-mode, is an operating regime possible in toroidal magnetic confinement fusion devices – mostly tokamaks, but also in stellarators. In this regime the plasma has a higher energy confinement time.

It was discovered by Friedrich Wagner and his team in 1982 during neutral-beam heating of the plasma at ASDEX. It has since been reproduced in all major toroidal confinement devices and is planned in the operation of ITER. Its self-consistent theoretical description was a topic of research in 2007. It was still considered a mystery with multiple competing theories (e.g. predator–prey model) in 2016.