Divertor radiation distribution during ELMs in JET

• Large ELMs are often compound (Type I ELM followed by Type III ELMs). • A significant fraction (up to 90% of radiated energy integrated over the compound phase) of the plasma energy degradation during the compound phase is exhausted by radiation. • About ∼50% of ΔW_ELM is radiated in the ELM energy range between 0.1MJ and 0.9MJ. • Large type I ELMs with energy losses above 0.7MJ show enhanced radiation losses, almost certainly associated with ablation of a re-deposited carbon layer in the inner divertor. • ELM-induced radiation is always higher at the inner than at the outer divertor: this asymmetry increases approximately linearly to ΔW_ELM ∼ 0.6 MJ, then decreases for higher ΔW _ELM. • The higher inner divertor radiation is consistent with (but not only due to) a higher ELM energy deposition at the inboard side observed with IR thermography. • Surface (layer) temperatures do not exceed ∼ 2000°C at the inner target. The maximum outer target temperature amounts to ∼ 800°C (no layers). In neither case is the surface temperature sufficient for bulk carbon ablation to occur. • During the "compound" phase plasma contamination can increase but does not usually lead to radiative collapse of the plasma.