HR: 0800h
AN: SM51B-01    [Abstracts]
TI: Role of DC Electric Fields and Wave Heating in Cavity Profiles of Depleted Density and Transverse Ion Acceleration in Laboratory and Space Plasmas
AU: * Koepke, M E
EM: mkoepke@wvu.edu
AF: West Virginia Univ., Physics Dept., Morgantown, WV 26506-6315, United States
AU: Reynolds, E W
EM: plasmaeric@yahoo.com
AF: West Virginia Univ., Physics Dept., Morgantown, WV 26506-6315, United States
AU: Knudsen, D J
EM: knudsen@phys.ucalgary.ca
AF: Univ. of Calgary, Dept. of Physics and Astronomy, Calgary, ALB T2N 1N4, Canada
AB: Laboratory experiments on the WVU Q Machine, test-particle simulations, and Monte Carlo simulations are shown to provide evidence for explaining the inhomogeneity in both the plasma-density profile and the ion- temperature profile associated with cylindrically symmetric lower-hybrid cavities observed by the GEODESIC sounding rocket, the OEDIPUS-C sounding rocket, and the Freja satellite. Two potential contributions to the inhomogeneous profiles are identified. Both mechanisms (one dc and the other ac) rely on finite values of the Larmor radius and can result in nonlocal effects that deplete ion density within the cavity and enhance ion density immediately outside the cavity to form ion-gyroradius-scale shoulders encircling the cavity perimeter. In the absence of waves, a cylindrically symmetric, radial, DC electric field can be responsible for a polarization shift that produces such inhomogeneity in the density profile [1]. In the presence of waves, wave-induced transverse ion acceleration occurring within the cavity can produce such inhomogeneity in the density profile [2]. In combination, the two effects are shown to be comparable, necessitating an interpretation that includes both mechanisms for quantitative agreement. For the lab data, laser-induced fluorescence techniques provide high resolution in coordinate space and velocity space. [1] Reynolds et al., Inhomogeneity scale lengths in a magnetized, low temperature, collisionless, Q-machine plasma column containing perpendicular-velocity shear, Phys. Plasmas 13, 092106 (2006). [2] Knudsen et al., Lower-hybrid cavity density depletions as a result of transverse ion acceleration localized on the gyroradius scale, J. Geophys. Res. 109, A04212 (2004). This research is supported by NSF.
DE: 7829 Kinetic waves and instabilities
DE: 7831 Laboratory studies and experimental techniques
DE: 7846 Plasma energization
DE: 7867 Wave/particle interactions (2483, 6984)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Joint Assembly