Fusion energy research has seen exciting recent breakthroughs. The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory has achieved ignition,^1,2 and in the United Kingdom, the Culham Centre for Fusion Energy’s Joint European Torus (JET) has produced a record 59 megajoules of fusion energy.³ Against this backdrop of advances, we provide an account of the earliest fusion discoveries from the 1930s to the 1950s.* Some of this technical history has not been previously appreciated—most notably the first 1938 reporting of deuterium-tritium (DT) 14-MeV neutrons at the University of Michigan by Arthur Ruhlig.⁴ This experiment had a critical role in inspiring early thermonuclear fusion research directions. This article presents some unique insights from the extensive holdings within Los Alamos National Laboratory’s archives—including sources typically unavailable to a broad audience.

A wager struck by two plasma physicists 34 years ago was finally fulfilled in June during the opening day of the 48th European Physical Society Division of Plasma Physics, when Robert Goldston, former director of the Department of Energy’s Princeton Plasma Physics Laboratory (PPPL), virtually presented a plaque to his friend and colleague Jean Jacquinot, former director of the Joint European Torus (JET), EUROfusion's flagship fusion experiment based at the Culham Centre for Fusion Energy in the United Kingdom. Their bet, and JET’s record-breaking achievements in 2021, were celebrated in an article published by PPPL on July 8.