An investigation of coupled energy and particle transport in tokamak plasmas

This paper examines some experimental evidence for coupling between particle and energy anspor t in tokamak plasmas and presents analytical and numerical investigations of this type of transport. This coupling generally leads to discrepancies between the effective thermal diffusivities inferred from analyses of power balance and perturbation measurements. Such discrepancies have been observed experimentally. Comparisons are presented between the results from the numerical solution of a coupled transport model and data fmm experiments with modulated heating carried out on the D I E machine. The salient featares of coupled transpon have been assessed and demonstrated to be fully consistent with experimental data: it has been shown that uansport matrices with relatively large off-diagonal components can lead to small apparent perturbations of the density, when the energy balance is perturbed, whilst still affecting the thermal transport considerably. Furthermore, perturbation measurements, used in conjunction with predictive transport codes, have emerged a a useful technique for validati.ting