Imaging of Helical Coherent Structures in the Reversed Field Pinch

Images obtained with soft X-ray tomography in the RFX reversed field pinch device are presented. They show that the plasma can be in two different regimes, characterized by a different degree of magnetic chaos. Evidence of a coherent helical structure emerging from the chaotic plasma core is shown. These images indicate the power of tomography, which allows the study of the dynamics of a Hamiltonian system like the magnetic field lines.