Electromagnetic effects on zonal mode generation and turbulent transport in tokamak plasmas

Miyato, Naoaki; Kishimoto, Yasuaki; Li, J.*; Tokuda, Shinji

Electromagnetic or finite beta effects on generation of zonal modes, which include zonal magnetic fields as well as the zonal flows, and turbulent transport are investigated by global fluid simulations of electromagnetic ion temperature gradient (ITG) driven turbulence. The zonal magnetic fields are generated at low order rational surface. Coarse choice of toroidal modes affects zonal magnetic field generation. Three drives for the zonal flows, Reynolds stress, Maxwell stress and geodesic transfer, are analysed. The Reynolds stress contribution balances with the geodesic transfer and drives the zonal flows in almost whole region. It is found that the Reynolds stress and the geodesic transfer contributions change sign at low order rational surfaces. This is not observed in the electrostatic case.