Dust remobilization experiments on the COMPASS tokamak

Dust remobilization is one of the not yet fully understood mechanisms connected to the prompt erosion of material from plasma facing surfaces in fusion devices. As a part of a newly initiated cross-machine study, dust remobilization experiments have been performed on the COMPASS tokamak. Tungsten samples with well-defined deposited tungsten dust grains, prepared using a recently developed controlled pre-adhesion method, have been exposed to ELMy H-mode discharges as well as L-mode discharges with forced disruptions. Here we report on the technical aspects of the experiment realization as well as on the experimental results of dust remobilization. The latter is discussed in the light of data from other machines and a physical interpretation is suggested for the observed spatial localization of the dust remobilization activity. Evidence of rearrangement of isolated dust into clusters and strings is also presented.