Analysis of rotation experiments in TFTR

The study of momentum confinement is a valuable means of investigating the mechanisms governing confinement in tokamak plasmas. A dedicated rotation experiment was conducted in TFTR, in September 1988, employing the recently installed CHERS diagnostic. Shots at different values of plasma current, magnetic field, injected beam power and injection direction were made, to study the parametric dependence of local fluxes of momentum and energy.

This Thesis is focused on the study of momentum confinement. Its purposes are to analyze the data of the TFTR rotation experiment, to document the results and to compare the experimental results with the predictions of neoclassical and anomalous momentum transport theories. Particular attention is devoted to the evaluation of the magnitude of the poloidal variation of densities and rotation frequencies that determine the magnitude of the gyroviscous momentum flux.

We find that: (1) Ware's cold ions theory underpredicts the observed viscosity by a few orders of magnitude; (2) each of the anomalous theories considered predicted torque flows which show magnitudes, radial profiles and parametric dependencies on plasma parameters different from those of the experimental torque flow; (3) up-down poloidal asymmetries of density and rotation frequency, evaluated with a model which neglects heat flux and includes the effect of anomalous particle fluxes, are found to be much smaller than $\epsilon$; (4) the gyroviscous torque is at least one order of magnitude smaller than the experimental torque flow.