An offset nonlinear scaling for ELMy H-mode confinement

An offset nonlinear scaling is developed for the ELMy H-mode by analysing the ITER H-mode database ITERH.DB2. The offset part of the stored energy is determined by the MHD stability of ELM, and the incremental confinement time of a nonlinear function of heating power is determined by the gyro-Bohm-like transport of the core plasma. This scaling predicts a lower confinement time for ITER than that predicted by general power-law scaling.