A prominent signature of plasma– a state of matter characterized by easily roaming charged particles connecting by means of electromagnetic forces– is the generation of “plasma waves,” resulting from an instability of plasma circulations. “Fast magnetosonic waves” (MSWs) are one type of electromagnetic plasma wave in the Geospace. MSWs result from hot protons and are considered “high frequency waves.”
Another type of wave frequently created in the Geospace is the “electromagnetic ion cyclotron” (EMIC) wave, which is thought about a “radio frequency wave.” Recently, satellite observations in the Geospace have actually shown that MSWs and EMIC waves often take place together. However, the system underlying this co-occurrence has actually stayed unclear.
Hot ions (red) create magnetosonic waves (MSWs; green), which then propagate throughout the field lines and heat up cold ions (yellow) by moving their energy to them. A part of this transferred energy goes into generating EMIC waves (blue). Credit: © ERG Science Team
Now, a team of scientists led by Professor Yoshizumi Miyoshi from Nagoya University, Japan, has rather unraveled this mechanism. “MSWs are understood to occur together with the heating of low-energy protons and studies have actually revealed that MSWs can heat up these cold ions. With the recent observation data by the Arase satellite showing synchronised EMIC waves, we questioned whether the look of EMIC waves is actually paired with the MSW-mediated ion heating process,” says Prof. Miyoshi, discussing the motivation behind the research study.
Appropriately, the group used a wave-particle interaction analysis technique to the MSWs and EMIC waves– which they observed with the Arase satellite– to take a look at the “cross-energy coupling” in between them through ion heating. The outcomes were informing: they discovered that while MSWs moved energy to the “cold” protons to heat them up, a part of the transferred energy of protons went into interesting the EMIC waves. Considering that MSWs were, in turn, delighted by hot protons, they, in truth, functioned as a mediating agent for energy transfer to the EMIC waves, i.e., a cross-energy coupling between hot protons, cold protons, MSWs, and EMIC waves.
While these findings are amazing in themselves, Prof. Miyoshi describes how they are of significance to our understanding about the Geospace too: “EMIC waves trigger substantial scattering and loss of killer electrons in the Van Allen radiation belts which frequently trigger satellite malfunctions. The brand-new energy transfer path for exciting EMIC waves exposed in our study might add to enhanced space weather condition forecasting, producing much safer operations of satellite in the Van Allen radiation belts.”
Perhaps more such interesting phenomena are waiting to be discovered amidst the riches of the Geospace!
Recommendation: “Cross-Energy Couplings from Magnetosonic Waves to Electromagnetic Ion Cyclotron Waves through Cold Ion Heating inside the Plasmasphere” by Kazushi Asamura, Masafumi Shoji, Yoshizumi Miyoshi, Yoshiya Kasahara, Yasumasa Kasaba, Atsushi Kumamoto, Fuminori Tsuchiya, Shoya Matsuda, Ayako Matsuoka, Mariko Teramoto, Yoichi Kazama, and Iku Shinohara, 10 December 2021, Physical Review Letters.DOI: 10.1103/ PhysRevLett.127.245101.
Arase satellite uncovers coupling in between plasma waves and charged particles in Geospace
Researchers unwind a bit more of the secret underlying how wave-particle interactions create other plasma waves in Geospace.
In a current research study published in Physical Review Letters, scientists from Japan show that high-frequency plasma waves in the Geospace can create low-frequency plasma waves through wave-particle interactions by warming up low-energy ions, unveiling a brand-new energy transfer path in collisionless plasma.
A popular signature of plasma– a state of matter characterized by freely strolling charged particles connecting via electro-magnetic forces– is the generation of “plasma waves,” resulting from an instability of plasma circulations. “Fast magnetosonic waves” (MSWs) are one kind of electromagnetic plasma wave in the Geospace. With the recent observation information by the Arase satellite showing synchronised EMIC waves, we questioned whether the appearance of EMIC waves is in fact combined with the MSW-mediated ion heating process,” says Prof. Miyoshi, explaining the inspiration behind the research study.
Considering that MSWs were, in turn, delighted by hot protons, they, in reality, acted as a mediating agent for energy transfer to the EMIC waves, i.e., a cross-energy coupling between hot protons, cold protons, MSWs, and EMIC waves.