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(EX/P1-08) Type I ELM Energy and Particle Losses in JET H Modes and Implications for ITER

A. Loarte1), JET EFDA Contributors
1) EFDA-CSU Garching Max-Planck-Institut für Plasmaphysik, Garching, European Commission

Abstract.  JET has achieved discharges that meet the ITER requirements ( q95, Zeff, < ne > /nGW, H98, etc.) in Type I ELMy H-modes at high triangularities. One of the problems for the full extrapolability of these discharges to ITER is the transient energy loads onto the divertor target associated with Type I ELMs that may lead to a limitation of the ITER target lifetime. Type I ELM energy losses decrease with increasing pedestal density and decreasing pedestal temperature, for a wide range of JET ELMy H-mode plasmas. The normalised ELM energy losses (DWELM/Wped) are well correlated with the pedestal plasma collisionality ( $ \nu^{\ast}_{ped}$). The reduction of DWELM/Wped with increasing $ \nu^{\ast}_{ped}$ is mostly due to the reduction of the temperature drop that the ELM causes (i.e., conductive losses). ELM particle losses (leading to convective losses) seem to be independent of $ \nu^{\ast}_{ped}$. Pure convective Type I ELMs have been observed in JET with a normalised energy loss of $ \sim$ 0.05, which is within the acceptable values estimated for ITER ($ \sim$ 0.07). On the basis of the JET ELM results, the implications for the expected ELM size and its convective/conductive nature in ITER will be described.

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IAEA 2003