HR: 0800h
AN: SM51A-1274    [Abstracts]
TI: Modeled and Observed Relationship Between Ion Energization and the Broadband ELF Spectrum
AU: * Coffey, V N
EM: Victoria.Coffey@nasa.gov
AF: NASA Marshall Space Flight Center, XD12, Huntsville, AL 35812 United States
AU: Singh, N
EM: Singh@ece.uah.edu
AF: University of Alabama in Huntsville, Sparkman Dr., Huntsville, AL 35812 United States
AU: Chandler, M O
EM: Michael.O.Chandler@nasa.gov
AF: NASA Marshall Space Flight Center, XD12, Huntsville, AL 35812 United States
AU: Miller, J A
EM: Millerja@uah.edu
AF: University of Alabama in Huntsville, Sparkman Dr., Huntsville, AL 35812 United States
AB: Many existing theories linking broadband ELF wave activity (BBELF) to ion energization and outflow are based on the gyroresonant heating of ions. Recent studies on the properties of these broadband waves show that other mechanisms may be more relevant. Using data from the Polar satellite, we previously presented the observed heating rate as a function of the electric field power spectral density (PSD). The resultant dependence was best fit by a power law with a spectral index of ~ +0.5. This is distinctly different from the linear dependence expected from a gyroresonant mechanism. We now combine our data analysis with numerical modeling to study the microphysics involved in this low-frequency wave generation and ion heating. Utilizing a 2.5D particle-in-cell simulation initialized with the ionospheric ion and electron precipitation distributions observed in the cusp, we will follow the excitation of lower hybrid waves, their very quick decay to the dominant lower frequency waves, and observe their wave structure. The subsequent heating rate and its dependency on the wave power in both wave number and frequency will be compared to the observed heating rate.
DE: 2451 Particle acceleration
DE: 2471 Plasma waves and instabilities (2772)
DE: 2483 Wave/particle interactions (7867)
DE: 2706 Cusp
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005