HR: 0800h
AN: SH51B-05    [Abstracts]
TI: Simulation study of EM radiation from Langmuir/z waves in warm magnetized plasmas
AU: * Kim, E
EM: ehkim@physics.usyd.edu.au
AF: School of Physics, University of Sydney, Sydney, New South Wales, 2006, Australia
AU: Cairns, I H
EM: cairns@physics.usyd.edu.au
AF: School of Physics, University of Sydney, Sydney, New South Wales, 2006, Australia
AU: Robinson, P A
EM: robinson@physics.usyd.edu.au
AF: School of Physics, University of Sydney, Sydney, New South Wales, 2006, Australia
AB: Linear mode conversion (LMC) of Langmuir waves to radiation near the plasma frequency at density gradients is relevant to solar and interplanetary radio bursts, planetary foreshocks, and perhaps pulsar radio emissions. We study LMC in warm magnetized plasmas using numerical electron fluid simulations as functions of the angles between the density gradient, ambient magnetic field (B₀), and wavevector. The dependences of the mode conversion efficiency on B0, spatial scales of density gradients, incidence angle θ of the Langmuir wave, relative to the density gradient, and the angle α between density gradient and B₀ are presented. The mode conversion window narrows as B₀ increases and the conversion efficiency increases as α increases. We show strong evidence that LMC produces extraordinary (x) mode as well as ordinary (o) mode radiation from Langmuir waves. Equal amounts of o- and x-mode radiation are produced in the unmagnetized limit at least when ¥á is small. Possible applications of LMC to the solar radio bursts in the solar wind and corona, and to planetary continuum radiation are also explored and it is suggested that LMC can explain linear and/or elliptical polarizations of type II and III solar radio bursts.
DE: 2100 INTERPLANETARY PHYSICS
DE: 2139 Interplanetary shocks
DE: 2159 Plasma waves and turbulence
DE: 7500 SOLAR PHYSICS, ASTROPHYSICS, AND ASTRONOMY
DE: 7534 Radio emissions
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Joint Assembly