Influence of ion-neutral collisions on the impact of edge biasing in a tokamak plasma

The effect of ion-neutral collisions on the dynamics of potential edge biasing in a tokamak plasma is studied. Under the influence of such collisions the ions and electrons drift differently thereby creating a non-ambipolar mechanism that impacts the radial electric field created by the biasing. This is similar to the effect of electron and ion mobilities that has been investigated in the past [1]. In this work, we carry out a consolidated investigation of the edge biasing dynamics in the presence of both ion-neutral collisions and electron/ion mobility contributions. Our detailed numerical simulations of an extended set of model equations reveal that both these contributions permit a different level of turbulence to exist. However, the extent of their individual impacts and influence on the spectral characteristics of the turbulence differ as a function of the plasma parameters. A detailed analysis of the physical origin of the stabilizing contribution due to ion-neutral collisions, followed by a comparison with similar effects arising from electron/ion mobility contributions will be presented.