Altitude dependent model of the auroral beam and beam‐generated electrostatic noise

Abstract

A height dependent model of the auroral beam and ionosphere is used to investigate the electrostatic noise generated by the auroral beam. The beam pitch angle is assumed to evolve with the first adiabatic invariant conserved. The beam generates whistler noise over most of the field line and upper hybrid noise only at low altitudes. Only a very narrow range of beam source densities generates noise without producing such large power fluxes that nonlinear effects are important. The strongest power fluxes in the auroral arc are likely to occur in the altitude range of a few thousand kilometers.