HR: 0800h
AN: SH41A-03    [Abstracts]
TI: Early In-Situ Results from STEREO/WAVES
AU: * Kellogg, P J
EM: kellogg@waves.space.umn.edu
AF: University of Minnesota, School of Physics and Astronomy 116 Church St. SE, minneapolis, MN 55455, United States
AU: Goetz, K
EM: goetz@waves.space.umn.edu
AF: University of Minnesota, School of Physics and Astronomy 116 Church St. SE, minneapolis, MN 55455, United States
AU: Monson, S J
EM: monson@waves.space.umn.edu
AF: University of Minnesota, School of Physics and Astronomy 116 Church St. SE, minneapolis, MN 55455, United States
AB: STEREO was launched toward the Earth's foreshock, which allowed some early results on two objectives of the in-situ part of the STEREO/WAVES experiment. The first subject is the harmonic content of Langmuir waves. This might play a role in the generation of the radio harmonic. Many previous measurements have been limited by possible nonlinearities in the measuring system. STEREO/WAVES uses 16-bit linear A/D converters, which are accurately linear. It is found that the harmonic content is quite variable, with sometimes no harmonics, sometimes the second harmonic (2 fp) and sometimes several harmonics. The harmonic content has little or no dependence on the amplitude of the primary. A second subject is the relation of Langmuir waves to density fluctuations. As is well known, typical Langmuir waves are generated so close to the ambient plasma frequency, and the fluctuations of plasma density are sufficiently strong, that the Langmuir waves should undergo frequent perturbations of their propagation, including reflection when their frequency becomes less than the local plasma frequency. Further, the density fluctuations imply that a bump-on-tail instability for a given wave number can only be resonant over a limited spatial region. Some preliminary observations of such effects will be presented.
DE: 6954 Radio astronomy
DE: 6984 Waves in plasma (7867)
DE: 7829 Kinetic waves and instabilities
DE: 7847 Radiation processes
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Joint Assembly