ELM Dynamics and Power Deposition in the JET Divertor

摘要

A new 2D infrared camera developed at JET has been able to measure the surface temperature evolution of the divertor with a time resolution of 15 μs which has proved to be necessary for ELM analysis. The peak power deposition during a type I ELM lasts about 130 μs with a maximum value in the range of 5 GW/m~2, most of the ELM energy being deposited on the inner divertor. The power and energy deposited during ELMs is overestimated by about a factor 3, due to uncertainties in the CFC properties at the surface. Extrapolations based on this data suggest that ITER cannot be operated in an ELMy discharge with type I ELMs unless the energy per ELM, compared to the stored energy, can be reduced far below the minimum achieved in the present tokamaks.