Impact of sheath evolution on ion impinging energy on the target during edge localized modes

The impact of the sheath evolution during edge localized modes (ELMs) on the ion impinging energy on the divertor target is studied by particle-in-cell simulation. A significant increase of the ion impact energy is obtained at the beginning of ELM. The arrival of the upstream bulk plasma leads to a suppression of the potential drop in front of the divertor target. The peak value of the ion impact energy emerges after the maximum potential drop in front of the divertor target. It is found that the peak value of the ion impact energy is increased by about 30% compared to the ion initial energy, which is induced by the potential drop during ELMs. (letter)