Microtearing modes in reversed field pinch plasmas.

In the reversed field pinch RFX-mod strong electron temperature gradients develop when the single-helical-axis regime is achieved. Gyrokinetic calculations show that in the region of the strong temperature gradients microtearing instabilities are the dominant turbulent mechanism acting on the ion Larmor radius scale. The quasilinear evaluation of the electron thermal conductivity is in good agreement with the experimental estimates.