Studies carried out on various tokamaks around the world, and in associated laboratories, have shown that plasma confinement improves with the size of the machine and deteriorates with the increase in the amount of additional heating.
In the 1980s, the scientific community defined a reference operating regime, partly thanks to the results obtained on the ASDEX machine (Germany): under certain conditions, plasma confinement improves spontaneously. This has made it possible to define a reference operating mode, called H mode (for High confinement), which will correspond to that of the ITER reactor. It defines a scaling law expressing the confinement time as a function of the machine’s main parameters.
