ELM simulation experiments on Pilot-PSI using simultaneous high flux plasma and transient heat/particle source

A new experimental setup has been developed for edge localized mode (ELM) simulation experiments with relevant steady-state plasma conditions and transient heat/particle source. The setup is based on the Pilot-PSI linear plasma device and allows the superimposition of a transient heat/particle pulse to the steady-state heat flux plasma. Energy densities as high as 1 MJ m(-2) have been reached for a pulse duration of about 1.5 ms, and for a variety of gases (H, He, Ar). In this contribution, we report on the first experiments investigating the effect of the combined steadystate/pulsed plasma on polycrystalline tungsten targets. Under such conditions the threshold for tungsten release and surface roughening is found to be much lower than in previously reported experiments. This suggests that the combination of the high flux plasma and transient heat/particle source leads to strong synergistic effects.