High‐frequency waves generated by auroral electrons

Measurements of marginally unstable electron distribution functions and high‐frequency plasma waves were made on a sounding rocket flight through a quiet auroral arc. The waves appeared near the electron plasma frequency and had a large parallel electric field component such that k∥ > k⊥. The appearance of these waves was correlated with the presence of marginally unstable parallel electron distributions. Analysis has shown that the waves were produced by ∂fe/∂ν∥ > 0 rather than the small ∂fe/∂ν⊥ > 0 features. Wave levels and growth rates inside the arc were small, and nonlinear wave‐wave and wave‐particle interactions appear to have been minimal.