Magnetic fluctuations and energy transport in RFX

In thermonuclear fusion plasmas, transport losses are usually believed to b e caused by turbulent fluctuations. Particularly in the outer region of tok amaks, stellarators and reversed field pinches, electrostatic turbulence ac counts for particle transport. In tokamaks, electrostatic fluctuations can also be responsible for the radial energy flux; in reversed field pinches, energy transport cannot be ascribed to electrostatic turbulence only. In the plasma edge of the reversed field experiment device, identified as t he region between the toroidal field reversal and the first wall, an extens ive study of magnetic fluctuations and of the related radial energy flux ha s been performed. It is found that magnetic fluctuations carry most of the radial flux of energy. However, close to the wall the magnetic fluctuation- driven energy flux decreases abruptly, so that another mechanism must be in voked. There are indications that the energy flux channel in this region is the macroscopic magnetic deformation due to the phase locking of magnetic modes.