The German plasma physicist who discovered the High-confinement mode (H-mode) on 4 February 1982 — a breakthrough that made ITER possible and remains the baseline operating regime for fusion reactors.
Friedrich (“Fritz”) Wagner (born 16 November 1943, Bavaria, Germany) joined the Max Planck Institute for Plasma Physics (IPP) in Garching in 1975. He became head of the ASDEX tokamak experiment in 1986 and a Scientific Fellow at IPP in 1988. He also habilitated at Heidelberg University in 1988.[1]
On 4 February 1982, during neutral-beam-heated experiments on the ASDEX tokamak, Wagner and colleagues observed a sudden, dramatic improvement in plasma confinement — energy confinement roughly doubled and edge turbulence nearly vanished. This transition from “Low-confinement mode” (L-mode) to “High-confinement mode” (H-mode) was soon reproduced worldwide.[2]
The discovery paper: Wagner, F. et al., “Regime of Improved Confinement and High Beta in Neutral-Beam-Heated Divertor Discharges of the ASDEX Tokamak,” Physical Review Letters 49(19), 1408, 1982. A comprehensive follow-up: Wagner et al., “The H-Mode of ASDEX,” Nuclear Fusion 29(11), 1989.[3]
Wagner received the John Dawson Award for Excellence in Plasma Physics Research (1987), the Hannes Alfvén Prize from the European Physical Society (2007), and the Stern-Gerlach Medal from the German Physical Society (2009).[4]