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

C. F. Driscoll, A. A. Kabantsev, D. H. E. Dubin, Yu. A. Tsidulko

Fusion Science and Technology / Volume 59 / Number 1T / January 2011 / Pages 170-175

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.

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