Edge coherent structures in RFX-mod high current regimes

The Reversed Field Pinch Experiment RFX-mod is characterized by a complex edge magnetic topology which is correlated with strong pressure gradients. It features also the presence of coherent electron pressure structures, resulting from nonlinear couplings between electron density, temperature and magnetic field. In this work we present measurements of edge parameters by an optical non-perturbing diagnostic (Thermal Helium Beam), which allows the studying of the edge turbulence up to 0.5MHz of high plasma current. The high-frequency HeI emission line has characterized from a Gas Puffing Imaging diagnostic, so it is possible to measure the electron density and temperature of the turbulence structures down to 2$\mu $s scale. From these measurements it appears that there is a clear correlation between better magnetic boundaries (SHAx states) and steeper electron pressure profiles. This has an impact upon global plasma performances since the dimension of edge coherent structures is also correlated with the characteristic pressure length.