Beam-generated electrostatic electron waves in the magnetosphere

The generation of growing electrostatic electron waves by electron beams in the ionosphere and magnetosphere is investigated. The auroral F-region, the high latitude exosphere, the auroral acceleration region around 1 R_e, altitude, the outer plasmasphere and the plasmasheet are treated. It is found that auroral electron beams can amplify electrostatic waves in all these regions but in different k-ranges. The growth rate, in terms of ω_i/ ω, generally increases outward. The propagation direction range of the waves discussed varies from a narrow cone around the magnetic field lines to all directions except close to the perpendicular. Strong cyclotron resonance effects at propagation angles close to 90 are not dealt with. The method used can easily be applied to any plasma system where free energy is available in the form of an electron beam, including laboratory plasma.