SCALINGS OF ION-TEMPERATURE-GRADIENT-DRIVEN ANOMALOUS TRANSPORT IN TOKAMAKS

Results are presented from the first systematic nonlinear gyrokinetic simulation study of the scalings and parameter dependences of toroidal ion-temperature-gradient-driven (ITG) turbulence and transport in lar ge magnetic-fusion-relevant tokamaks. Such simulations are made possib le by significant advances in computational physics algorithms which a re summarized. The simulated ion-thermal transport rates have clear '' gyroreduced Bohm'' scaling and are too low to account for the anomalou s transport seen in the outer half of some TFTR L-mode discharges, ind icating that additional mechanisms, such as nonadiabatic-electron effe cts, are operative.