Plasmas are swirling mixtures of gas so hot that many of the constituent atoms have been stripped of their electrons, creating a dynamic field of both negatively and positively charged particles that are strongly influenced by magnetic and electrical fields. Plasmas account for more than 99% of matter in the universe and can disrupt satellite navigation systems and other technologies, but scientists are still working to understand the fundamental processes occurring within them.
Usanova et al. report new observations of plasma waves in the magnetosphere, the region surrounding our planet where Earth’s magnetic field controls the charged particles. Using data from the FIELDS instruments aboard NASA’s Magnetospheric Multiscale satellites, the team identified a series of electromagnetic ion cyclotron waves—high-frequency oscillations that can be divided into several bands on the basis of their vibrational frequencies—within the plasma sheet boundary layer during a 3-day period in May of 2016.
In addition to measuring multiple harmonics of these waves in the oxygen frequency band, the satellite instruments also unexpectedly detected other accompanying waves, including higher-frequency broadband and whistler mode chorus waves that modulate at the same frequency. By presenting the first simultaneous observations of these various wave types, this study is likely to open up an entirely new area of inquiry into cross-frequency wave interactions at both electron and ion scales. (Geophysical Research Letters, https://doi.org/10.1029/2018GL079006, 2018)
—Terri Cook, Freelance Writer