Prior information for nonlinear modelling of tokamaks
This report is concerned with the construction of abstract mathematical models for experimentally observed tokamak behaviour, and their identification with experiment. Simple nonlinear models constrained by symmetry are proposed for different patterns of tokamak behaviour, viz. (1) tearing modes, (2) regular sawteeth oscillations , (3) fishbones, (4) edge-localised modes (ELMs) and control, (5) resistive wall modes (RWMs) and (6) compound sawteeth. Other physics-based models are also catalogued. Techniques for comparing and in some cases fitting the models to tokamak time series data are also briefly discussed, and the implications of successful comparison work highlighted.