Volume 124, Issue 7 p. 5709-5718
Research Article

The Role of Intense Upper Hybrid Resonance Emissions in the Generation of Saturn Narrowband Emission

J. D. Menietti

Corresponding Author

Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA

Correspondence to: J. D. Menietti,

john‐menietti@uiowa.edu

Search for more papers by this author
P. H. Yoon

Korea Astronomy and Space Science Institute, Daejeon, South Korea

School of Space Research, Kyung Hee University, Yongin, South Korea

Institute for Physical Science and Technology, University of Maryland, College Park, MD, USA

Search for more papers by this author
D. Pisa

Department of Space Physics, IAP, CAS, Prague, Czech Republic

Search for more papers by this author
T. F. Averkamp

Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA

Search for more papers by this author
A. H. Sulaiman

Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA

Search for more papers by this author
W. S. Kurth

Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA

Search for more papers by this author
O. Santolík

Department of Space Physics, IAP, CAS, Prague, Czech Republic

Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic

Search for more papers by this author
C. S. Arridge

Department of Physics, Lancaster University, Lancaster, UK

Search for more papers by this author
First published: 18 July 2019
Citations: 2

Abstract

Twenty high‐inclination ring‐grazing orbits occurred in the final period of the Cassini mission. These orbits intercepted a region of intense Z‐mode and narrowband (NB) emission (Ye et al., 2010, https://doi.org/10.1029/2009JA015167) along with isolated, intense upper hybrid resonance (UHR) emissions that are often associated with NB source regions. We have singled out such UHR emission seen on earlier Cassini orbits that also lie near the region crossed by the ring‐grazing orbits. These previous orbits are important because Cassini electron phase‐space distributions are available and dispersion analysis can be performed to better understand the free energy source and instability of the UHR emission. We present an example of UHR emission on a previous orbit that is similar to that observed during the ring‐grazing orbits. Analysis of the observed plasma distribution of the previous orbit leads us to conclude that episodes of UHR emission and NB radiation observed during the ring‐grazing orbits are likely due to plasma distributions containing loss cones, temperature anisotropies, and strong density gradients near the ring plane. Z‐mode emissions associated with UHR and NB emission can be in Landau resonance with electrons to produce scattering or acceleration (Woodfield et al., 2018, https://doi.org/10.1038/s41467‐018‐07549‐4).