The electron-acoustic and beam-driven modes associated with electron beams have previously been identified and studied numerically. These modes are associated with Broadband Electrostatic Noise found in the Earth's auroral and polar cusp regions. Using a 1-D spatial Particle-in-Cell simulation, the electron-acoustic instability is studied for a magnetized plasma, which includes cool ions, cool electrons and a hot, drifting electron beam. Both the weakly and strongly magnetized regimes with varying wave propagation angle, theta, with respect to the magnetic field are studied. The amplitude and frequency of the electron-acoustic mode are found to decrease with increasing theta. The amplitude of the electron-acoustic mode is found to significantly grow at intermediate wave-number ranges. It reaches a saturation level at the point, where a plateau forms in the hot electron velocity distribution after which the amplitude of the electron-acoustic mode decays. (C) 2014 AIP Publishing LLC.
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