He was known to have discovered the high-confinement mode (i.e. H-mode) of magnetic confinement in fusion plasmas while working at the ASDEX tokamak in 1982.
At first, he worked on low-temperature physics, but switched to plasma fusion research during the energy crisis of the time.
In 1975, he started working for the Max Planck Institute for Plasma Physics, and in 1986 he led the tokamak experiment ASDEX.
[5] In 2007, he received the Hannes Alfvén Prize from the European Physical Society for his contributions to fusion research by magnetic confinement.
[7] He was awarded in honor of his work in high-temperature plasma physics and fusion research, especially for the discovery of self-organizing transport barriers (i.e. H-mode), which was groundbreaking for the mastery of fusion plasmas.