Growing ion holes as the cause of auroral double layers

The nonlinear ion‐hole instability is proposed as the cause of intermittent double layers observed in the auroral particle acceleration region. A novel feature of the instability is its occurance in plasma that is stable to linear ion acoustic waves. A growing ion‐hole has a double layer potential structure. We demonstrate here that nonlinear hole instability is consistent with S3‐3 and Viking satellite data. Instability thresholds, as well as characteristic double layer amplitudes, potential drops, speeds, and scale sizes are calculated. The inadequacy of conventional linear instability models in explaining the data is discussed.