Robert Aymar studied at the École polytechnique before joining the Corps des Poudres (a former government agency of military engineers involved in basic and applied research). He then carried out research at the French Atomic Energy and Alternative Energies Commission (CEA) on plasma physics and its applications to nuclear fusion.

In 1977, Robert Aymar was appointed head of the Tore Supra project, to be built in Cadarache (France). From 1977 to 1988, he initiated the design and ensured the commissioning of Tore Supra, the only French tokamak in operation. Tore Supra is one of the few tokamaks to use superconducting coils to generate a strong magnetic field over a long period. It is also the only tokamak capable of continuously extracting the power injected into the plasma using components cooled by a pressurised water loop.
In 1990, Robert Aymar was appointed as the head of the Science of matter division at the CEA. In this capacity, he launched a wide range of research projects, both experimental and theoretical, in fields such as astrophysics, particle physics, high-energy physics, paleoclimatology and thermonuclear fusion. A year later, he created the Department of Astrophysics, Particle Physics, Nuclear Physics and Associated Instrumentation (DAPNIA).

Robert Aymar continued his career as Director of the International Thermonuclear Experimental Reactor (ITER), before becoming Director-General of CERN, the world’s largest research centre for high-energy physics, from 2004 to 2008.