Experimental evidence of the pre-plasma remobilization of ferromagnetic dust in FTU
is presented. Thomson scattering data and IR camera observations document the occurrence
of intrinsic dust remobilization prior to discharge start-up and allow for a rough
calculation of the average mobilized dust density. Exposures of calibrated extrinsic
non-magnetic and ferromagnetic dust to sole magnetic field discharges reveal that
the magnetic moment force is the main mobilizing force, as confirmed by theoretical
estimates. Pre-plasma remobilization probabilities are computed for varying dust sizes.
The impact of prematurely remobilized dust on the breakdown and burn-through start-up
phases is investigated together with the discharge termination induced once the plasma
plateau is established.