Simulation of Joint European Torus beta scan experiments using theory-based models

Transport modeling of beta (β) scaling experiments performed in the Joint European Torus (JET) [P. H. Rebut et al., Nucl. Fusion 25 1011 (1985)] is presented. Two theory-based models are used: the Weiland model [F. D. Halpern et al., Phys. Plasmas 15, 012304 (2008)] and the gyro-Landau-fluid model GLF23 [J. E. Kinsey et al., Phys. Plasmas 12, 062302 (2005)]. First, the β dependence of energy transport in each model is illustrated by running them stand-alone with imposed plasma profiles obtained in JET β scaling experiments. Both models show a stabilization of ion temperature gradient modes with increasing β up to a critical β value for which ballooning modes become unstable, leading to a strong degradation of the core confinement. Second, the models are used in predictive simulations of heat transport in order to test the capability of the models to reproduce experimental results. A good agreement between the Weiland model and experimental results is found, but the model sensitivity to dimensionless parameters mismatches throughout the experimental scan strongly affects the apparent scaling. This is tested by running predictive simulations using modified input parameters in order to correct the mismatch. In order to identify which dimensionless parameter mismatches are responsible for the apparent scaling, a sensitivity analysis of the Weiland model is performed. A comparison with modeling of previous experimental results is also presented.