The Fusion and Astrophysical Plasma Physics Group within the Physics Department and the Center for Astrophysics and Space Sciences at the University of California, San Diego is led by Professor Patrick H. Diamond, Distinguished Professor of Physics, and consists of two research scientists-- Mikhail Malkov, Fred Hinton, one Postdoctoral Scholar and two graduate student researchers-- and is managed by an administrative assistant.
Spontaneous Profile Self-Organization in a Simple Realization of Drift-Wave Turbulence
L. Cui, A. Ashourvan, S.C. Thakur, R. Hong, P.H. Diamond and G.R. Tynan
We report the observation of a transport bifurcation that occurs by spontaneous self-organization of a drift-wave and shear flow system in a linear plasma device. As we increase the magnetic field above a threshold (B_Cr = 1200 G), a global transition occurs, with steepening of mean density and ion pressure profiles, onset of strong E×B shearing, a reduction of turbulence, and improved turbulent radial particle transport. An abrupt transition appears in the graph of turbulent particle flux versus density gradient. Hysteresis in the density gradient further confirms this transportbifurcation. The total Reynolds work on the flow sharply increases above threshold. This correlates with the increase of density steepness, which suggests the Reynolds stress-driven flow that plays an essential role in density steepening and transportbifurcation. A change in turbulence feature from drift waves (DWs) to a mix of DWs and ion temperature gradients also coincides with the transportbifurcation. Interesting phenomena related to the transportbifurcation are also reported; a local inward particle flux, the co-existence of ion and electron features, and a self-sustained axial flow absent momentum input.
To the memory of Professor Marshall N. Rosenbluth - an American plasma physicist and member of the National Academy of Sciences - who passed away on September 23, 2003.
We are working primarily on the theory of fusion plasma including: