HR: 1340h
AN: NG43A-0565    [Abstracts]
TI: Nonlinear Beat-Wave Interaction Between Shear Alfven Waves in a Laboratory Plasma
AU: * Brugman, B
EM: brugman@physics.ucla.edu
AF: Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA 90095
AU: Carter, T A
EM: tcarter@physics.ucla.edu
AF: Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA 90095
AB: Alfvén waves are ubiquitous in space plasmas such as earth's magnetosphere and the solar wind. The nonlinear dynamics of Alfvén waves is believed to play an important role in these plasmas, for example through the generation of magnetic turbulence, particle acceleration, and ponderomotive forces. Nonlinear interactions between Alfvén waves are being studied in the Large Plasma Device (LAPD) at UCLA, using large amplitude, δ B / B_O ~ 1 % waves generated by an Alfvén wave MASER or by antennas. In these experiments, two large amplitude shear Alfvén waves are launched at different frequencies and beat against one another. The subsequent nonlinear generation of density fluctuations at the beat frequency along with the formation of numerous discrete Alfvénic sidebands has been observed using both wave launching mechanisms over a broad range of plasma parameters and launch wave frequencies. Such interactions resemble a form of parametric decay, namely the modulational instability. We will present detailed measurements of this beat-wave interaction in particular the spatial and temporal characteristics as well as amplitude scaling.
DE: 0689 Wave propagation (2487, 3285, 4275, 4455, 6934)
DE: 2487 Wave propagation (0689, 3285, 4275, 4455, 6934)
DE: 4455 Nonlinear waves, shock waves, solitons (0689, 2487, 3280, 3285, 4275, 6934, 7851, DE: 7829 Kinetic waves and instabilities
DE: 7839 Nonlinear phenomena (4400, 6944)
SC: Nonlinear Geophysics [NG]
MN: Fall Meeting 2005