Electromagnetic Ion Cyclotron (EMIC) Waves

April 19, 2023

Scientists from the Indian Institute of Geomagnetism (IIG) have identified and studied Electromagnetic Ion Cyclotron (EMIC) waves, a form of plasma waves observed in the Earth’s magnetosphere, at the Indian Antarctic station, Maitri.

Plasma – The Fourth State of Matter

More than 99% of the visible universe consists of plasma, which is the fourth state of matter. It is a highly ionized gas consisting of charged particles that react to electromagnetic fields. The Sun, solar wind, interplanetary medium, near-Earth region, magnetosphere, and upper part of our atmosphere all consist of plasma. The study of plasma waves provides the critical information about regions that are inaccessible to us, enabling the better understanding of how they interact with charged particles, and control the overall dynamics of the Earth’s magnetosphere.

The Significance of EMIC Waves

EMIC waves are a type of traversing plasma waves observed in the Earth’s magnetosphere that can resonate with electrons with a wide energy range – from 500 keV to hundreds of MeV. They make these electrons precipitate to the high-latitude atmosphere, leading to the formation of the radiation belt of the planet Earth. These killer electrons are hazardous to space-borne technology and instruments.

The Study of EMIC Waves

The scientists from IIG analysed data collected between 2011 and 2017 by the Induction Coil Magnetometer data, installed at the Indian Antarctic station Maitri to study the EMIC waves. They identified the location of the generation of the waves in space and suggested that the lower-frequency waves modulate the higher-frequency waves.

Improving Our Understanding of EMIC Waves

The study discovered that short-period modulation of such wave events is common and relies on EMIC wave frequency. It also showed that the short period decreases with an increase in the peak frequency of the EMIC wave, and stronger EMIC wave events were likely to have a higher peak frequency. The study aimed to improve our understanding of EMIC wave modulation and their interaction with energetic particles that impact satellites and their communication.

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