Radiation of VLF/ELF waves from a magnetospheric tether

Abstract

The high energy particles of the Van Allen belts coming from cosmic rays, solar storms, high altitude nuclear explosions (HANEs) and other processes represent a significant danger to humans and spacecraft operating in those regions, as well as an obstacle to exploration and development of space technologies. The "Radiation Belt Remediation" (RBR) concept has been proposed as a way to try to solve this problem through VLF/ELF transmissions in the ionosphere, which will create a pitch-angle scattering of these energetic particles with some of them falling into their loss cone, thus reentering the Earth. The aim of this thesis is to develop an analytical model of propagation and radiation of Electromagnetic Ion Cyclotron Waves (EMIC) from a high-voltage magnetospheric tether, which are the waves proposed to scatter protons. The plasma is anisotropic due to the external Earth's magnetic field and it is assumed to have sufficiently low density, temperature and degree of ionization so that collisions and thermal velocities can be neglected. An asymptotic analysis is developed to calculate the fields and power flux radiated by the tether that reach a specified observation point located in the far-field region. The effect of the antenna-plasma interaction in the far-field region is studied by adding to the conventional triangular source current distribution along the antenna a radial current arising from the sheath region. The near-field case and the radiation impedance are as well studied. Finally, the results are analyzed and compared with previous models for limiting cases.