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arXiv · 2108.07802

Triggered ion acoustic waves in the solar wind

Forrest S. Mozer·Ivan . Y. Vasko·J. L. Verniero
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Abstract

For more than 12 hours beginning on January 18, 2021, continuous narrowband electrostatic emissions were observed on Parker Solar Probe near 20 solar radii. The observed <1000 Hz frequencies were well below the local ion plasma frequency. Surprisingly, the emissions consisted of electrostatic wave packets with shock-like envelopes, appearing repetitively at a ~1.5 Hz rate. This repetitiveness correlated and was in phase with low frequency electromagnetic fluctuations. The emissions were associated with simultaneously observed ion beams and conditions favorable for ion-acoustic wave excitation, i.e. Te/Ti~5. Based on this information and on their velocity estimates of about 100 km/s, these electrostatic emissions are interpreted as ion-acoustic waves. Their observation demonstrates a new regime of instability and evolution of oblique ion-acoustic waves that have not been reported previously in theory or experiment.

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Forrest S. Mozer, Ivan . Y. Vasko, J. L. Verniero. 2021-08-17. Triggered ion acoustic waves in the solar wind. https://doi.org/10.3847/2041-8213%2Fac2259

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