Intrinsic rotations in bi-configurable RFX-mod device

Although its origin is not well understood yet, toroidally confined plasmas possess an intrinsic (spontaneous) rotation that is believed to be an important ingredient for the transition to high confinement modes [1], to improve the MHD stability, screening penetration of Resonant Magnetic Perturbations and in general to reduce the turbulent fluctuations [2]. Large toroidal velocities of several kilometers per second are observed in absence of external momentum input [3]. RFX-mod contributes to the study of certain aspects of thisphysics by exploiting on the one hand its capability to operate both as a reversed field pinch experiment and as a low current ohmic tokamak [4], and ,on the other hand, its powerful set of MHD feedback control system [5]. The latter allows to study a variety of 3D magnetic perturbations andtheir interaction with the plasma. This work reviews the main results on flow measurements in both RFP and tokamak configurations by passive Doppler spectroscopy. Plasma rotation dependencies on the main plasma parameters will be compared and the effect of the magnetic boundary inmodifying the plasma rotation will be discussed. References [1] Asdex Team, Nucl. Fusion 29(1898) 1959 [2] Angioni C. et al, PRL 107, 215003 (2011) [3] Rice J. E. et al, Nucl. Fusion 47(2007) 1618 [4] Martin P. et al., "Overview of the RFX-mod fusion science program", submitted to Nucl. Fusion [5] Piovesan P. et al.," RFX-mod: a multi-configuration fusion facility for 3D physics studies", accepted for publication in Phys. Plasmas (2013)