Spontaneous L-mode plasma rotation scaling in the TCV tokamak

Predicting intrinsic plasma rotation and its shear, which often help stabilize plasma instabilities affecting plasma performance, is important for prospective fusion grade devices. Although rotation in ITER-like scenarios has been extrapolated from measured experimental plasma rotation data, little is understood about the underlying mechanisms governing either the generation or dissipation of momentum in a tokamak plasma. This paper reports on studies of intrinsic toroidal and poloidal plasma rotation from charge exchange spectroscopy using a low power diagnostic beam on the TCV tokamak [Tonetti et al., in Proceedings of the Symposium on Fusion Technology (1991), p. 587] that drives negligible toroidal velocity. In TCV, plasma behavior can be separated by the core and edge regions. In limited configurations, the core rotates in the counter-current direction and can reverse to the co-current direction with a <10% increase in the plasma density. This is different for diverted configurations where the core r...