| Tokamak de Fontenay-aux-Roses | |
|---|---|
| Device type | Tokamak |
| Location | Fontenay-aux-Roses, Paris, France |
| Affiliation | Commissariat à l'énergie atomique |
| Technical specifications | |
| Major radius | 98 cm (39 in) (often listed as 1 m) |
| Minor radius | 20 cm (7.9 in) (later 24 cm (9.4 in)) |
| Plasma volume | 1 m3 |
| Magnetic field | 6.0 T (60,000 G) (toroidal) |
| Heating power | 2.2 MW |
| Discharge duration | 0.25 s |
| Plasma current | 400 kA (later 600) |
| Plasma temperature | 3 keV (electrons) |
| History | |
| Date(s) of construction | 1970 to 1973 |
| Year(s) of operation | 1973–1986 |
| Succeeded by | Tore Supra |
The Tokamak de Fontenay-aux-Roses (TFR) was the first French tokamak, built in a research centre of the French Atomic Energy Commission (CEA) in Fontenay-aux-Roses, a commune in the southwestern suburbs of Paris. The project was spearheaded by Paul-Henri Rebut, and is sometimes jokingly referred to as the "Tokamak façon Rebut" – a pun on the name Rebut and the French word "rebut" meaning "rubbish".
TFR was roughly the same size as the contemporary Soviet T-3 and American Symmetrical Tokamak, but had a larger internal plasma volume and a much more powerful power supply that drove plasma currents up to 400,000 amps and as long as half a second. Completed in 1973, it remained the world's most powerful tokamak until 1976, when it was surpassed by the Princeton Large Torus. It underwent several major upgrades during its lifetime, which continually improved its performance.
Among the major discoveries made on TFR was the problem of runaway electrons. In 1973, only months after beginning operations, such an event burned holes through the vacuum vessel, requiring extensive repairs. The following investigation identified a new type of plasma instability that was previously not noticed, today known as neoclassical transport. Since this time a number of similar issues have been found and they are now all classified as "disruptions".
A replacement vacuum vessel was quickly supplied and the device soon reached its design goals. It was later expanded several times with more powerful power supplies and more heating systems. TFR was decommissioned in 1986, at which time it was the oldest operating tokamak. It was replaced by Tore Supra at France's main atomic research center, Cadarache.