Transport from a Ruffled Separatrix Axial trapping separatrices are ubiquitous in plasmas and traditional NeoClassical Transport theory calculates transport effects from collisional separatrix crossings ID: 601009
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Chaotic Neo-Classical
Transport from a "Ruffled" Separatrix
Axial trapping separatrices are ubiquitous in plasmas, and
traditional Neo-Classical Transport theory calculatestransport effects from collisional separatrix crossings.Recent experiments and theory show that chaoticseparatrix crossings may dominate, arising from plasmarotation across a "ruffled" separatrix Φs = V0 + ΔVmcos(mθ),or from wave-induced separatrix fluctuations.
Here, a magnetic tilt "error field" causes plasmaexpansion at rate νP. The chaotic transport shows anun-ambiguous sin2α signature, where α is the anglebetween the separatrix ruffle and the magnetic tilt.Chaotic transport is proportion to the ruffle ΔVm,and adds to the baseline collisional transport (orange). Two different collisionality and magnetic scalings are seen: Chaotic νP ~ νc0 B-1 Collisional νP ~ νc1 B-1/2Recent experiments and theory characterize this chaoticseparatrix dissipation during the parametric decay instabilitybetween drift waves.
ν
P
Driscoll /Dubin /O'Neil, UCSD
A.A.Kabantsev et al Phys.Rev.Lett
112
,055003 (2014)