The isotope dependence of the H-mode power threshold and the energy confinement time have been examined in dedicated experiments on the Joint European Torus (JET) in hydrogen, deuterium and tritium plasmas. The results show that: (1) The H-mode power threshold is inversely proportional to the effective isotopic mass, M, of the plasma. (2) The edge electron pedestal temperature at the L to H-mode transition scales as . (3) The global thermal energy confinement time, , does not depend strongly on M, i.e. in the ohmic, L-mode, edge localized modes (ELMy) and ELM-free H-mode confinement regimes with , if the engineering parameters such as current, magnetic field, density, power and geometry are kept fixed. (4) In the ELMy H-mode regime the transport in the core and the edge of the plasma scale differently with M, i.e. the core transport increases weakly with M whereas the edge transport decreases strongly with M.
Isotope scaling of the H mode power threshold on JET