Overview of Transport, Damping, and Wave Couplings from Separatrix Dissipation in an Axisymmetric Plasma

Axial variations in magnetic or electrostatic confinement fields create local trapping separatrices, and traditional neo-classical theory analyzes the effects from collision-induced separatrix crossings. Recent experiments and theory have characterized the distinctive neo-classical effects from chaotic separatrix crossings, induced by equilibrium plasma rotation across -ruffled separatrices, or by wave-induced separatrix fluctuations. Experiments on nominally-symmetric pure electron plasmas with controlled separatrices agree quantitatively with theory in 3 broad areas: 1) radial particle transport is driven by a static z- and -asymmetry; 2) both E × B drift waves and Langmuir waves are damped; and 3) novel dissipative wave-wave couplings are observed. The new chaotic neo-classical effects scale as ⁰B^-1, whereas traditional plateau-regime collisional effects scale as ^1/2B^-1/2.