Doppler spectroscopy and collective flows in RFXmod

Doppler spectroscopy based toroidal and poloidal flow velocities measured on the modified RFX Reversed Field Pinch are compared with the results obtained in the previous machine [1]. Passive measurements with integrated lines of sight confirm the decaying dependence of the toroidal plasma velocity with electron density but show a higher dynamics with respect to the past, often featuring significant accelerations during the plasma discharge$. $Edge flow, opposite to the core co-current flow, in presence of induced bulges of localized MHD modes or externally induced radial magnetic perturbations reverses its direction: this corresponds to a reversal of the radial electric field. A new diagnostic neutral beam injector (50 kV, 2.5 A equivalent current) has been recently installed for spatially resolved measurements. Preliminary results are presented. Among the main objectives of the system is a detailed measurement of the radius at which the radial electric field reverses and whether such radius coincides with the magnetic field reversal. [1] \textit{L. Carraro et al. }Plasma Phys. Control. Fusion \textbf{40} (1998) 1021-1034.