More Cross Phase Modification through Drive Adjustment to Control I-mode Transport*

Novel enhanced confinement regimes such as the I-mode and similar new transport regimes offer good confinement properties with reduced density limit issues and potentially better control. Few if any suggested mechanisms allow enhanced confinement in one channel but not another which is seen in the I-mode.  We have proposed differential cross-phase modification as a possible mechanism for different transport in different channels and investigate control tools. In this work we present new GENE simulations with various and multiple instability drives to test the plausibility of this mechanism.  Included are ITG, ETG and TEM and start with linear simulation then extent to fully nonlinear simulations. Following these results, we use a simple dynamical model which has been able to capture a remarkable amount of the dynamics of core and edge transport barriers to further explore the dynamics of more continuous transitions such as the I-mode with this mechanism. We look at I-mode transitions and explore using differential electron and ion heating to control the I-mode regime in the simpler model and we demonstrate the ability to stay in the I-mode without slipping into the H-mode regime.