VLF/LF Whistler Mode Wave Injection and Radio Sounding Experiments from the Demonstration and Science Experiments (DSX) Satellite

Whistler mode wave injection and radio sounding experiments (3-50 kHz) from the Demonstration and Science Experiments (DSX) satellite (6000 x 12,000 km, 42 deg inclination) offers a new opportunity to address some of the fundamental problems in magnetosphere physics: (1) nonlinear wave-particle interactions, (2) propagation of VLF/LF signals from a magnetospheric source (e.g. DSX) to the ground and to other satellites (e.g. Van Allen Probe), (3) whistler mode radio sounding of electrons, ions, and plasma density irregularities, and (4) behavior of electric field antennas at whistler mode frequencies during the wave injection experiments. We present ray tracing simulations of whistler mode wave propagation of DSX signals in the magnetosphere and to the ground. Ray tracing results show that four types of echoes are predicted when DSX transmits within the whistler mode frequency range: (1) magnetospherically reflected (MR), (2) normally incident specularly reflected (NI), (3) obliquely incident specularly reflected (OI), and (4) plasmapause reflected (PP). The characteristic dispersion of these echoes can be used to determine the electron density, ion composition, and location and scale sizes of density irregularities in the magnetosphere along the echo ray paths using the methods discussed by Sonwalkar et al. [JGR, 2004, 2011]. Ray tracing results also show that DSX signal can potentially reach the ground by three distinct mechanisms: (a) nonducted propagation at small wave normal angles, (b) nonducted propagation at large wave normal angles followed by a mode conversion process involving field aligned irregularities, and (c) ducted propagation. Ray tracing simulation based estimates of signals strengths of the signal reaching the ground by these various methods indicate that the most likely mechanisms by which DSX signals may reach the ground are: (1) at 3 kHz, nighttime ducted propagation with ground electric field strength ~0.2 μV/m, and (2) at 15 kHz, nighttime nonducted propagation followed by mode conversion with ground electric field strength ~1-10 μV/m. We discuss the implications of our results for addressing the fundamental problems mentioned above.