Distinguishing Bounce-Resonant from Bounce-Averaged Neo-Classical Transport

Experiments, theory, and simulation for single-species plasmas now show quantitative agreement for both Bounce-Resonant (BR) and Bounce-Averaged (BA) Neo-Classical Transport, with distinct magnetic field scalings over $0.5 < B < 12.$kG. Here, we consider cylindrical pure electron plasmas, with particle orbit excursions caused by a global ``field error'' such as magnetic tilt (analogous to global toroidal curvature); and with controlled electrostatic separatrices producing populations of trapped and un-trapped particles. With distinct trapped-particle populations, BA theory correctly describes both {\it collisional} NCT scaling as $\nu^{1/2} B^{-1/2}$, and the novel {\it chaotic} NCT scaling as $\nu^0 B^{-1}$ which occurs when the separatrix is ``ruffled'' in the $E \times B$ drift direction.\footnote{A.A. Kabantsev {\it et al.}, Phys. Rev. Lett. {\bf 105}, 205001 (2010); D.H.E. Dubin and Yu.A. Tsidulko, Phys. Plasmas {\bf 18}, 062114 (2011).} For weak magnetic fields, BR transport dominates, typically scaling as $B^{-2}$ to $B^{-3}$, with different scalings observed for $z$-extended and $z$-localized field errors. Also, we are able to observe the transition from banana regime to plateau regime, with dependence on applied error field strength $\epsilon$ changing from $\epsilon^2$ to $\epsilon^{1/2}$.