Turbulence induced by the ion temperature gradient (ITG) is investigated in
the helical and axisymmetric plasma states of a reversed field pinch device by
means of gyrokinetic calculations. The two magnetic configurations are
systematically compared, both linearly and nonlinearly, in order to evaluate
the impact of the geometry on the instability and its ensuing transport, as
well as on the production of zonal flows. Despite its enhanced confinement, the
high-current helical state demonstrates a lower ITG stability threshold
compared to the axisymmetric state, and ITG turbulence is expected to become an
important contributor to the total heat transport.Comment: 8 pages, to appear in Phys. Plasma
