Spontaneous Profile Self-Organization in a Simple Realization of Drift-Wave Turbulence
Lang Cui, UC San Diego / Princeton Plasma Physics Laboratory
Monday, November 9, 4:00pm
SERF, Room 383
Abstract: We report the observation of a transport bifurcation that occurs in a spontaneous self-organization in a simple drift-wave system. As we increase the magnetic field above a threshold (B =1200G), a global transition has been seen in steepening of mean density and ion pressure profiles, strong EXB shearing, reduction of turbulence and improved turbulent radial particle transport. Abrupt transition is shown in the turbulent particle flux versus density gradient. Hysteresis in density gradient further confirmed this transport bifurcation. The total Reynolds work sharply increase above threshold that correlates with the sharp increasing of density steepness, which suggests the Reynolds stress-driven flow plays an essential role in density steepening and transport bifurcation. A change in turbulence feature from DWs to mixing DWs and ITGs also coincides with the transport bifurcation. Several interesting phenomena related to the transport bifurcation are also reported: the local inward particle flux, the co-existence of ion and electron feature and the self-sustained axial flow.