How Kinetic Processes Coupling Particles and Waves Govern Heliospheric Plasmas
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Dr. Mihailo Martinovic
Researcher/Scientist
Lunar and Planetary Laboratory
University of Arizona
The solar wind is a fully ionized plasma streaming away from the Sun at several hundred kilometers per second. Measurements of the solar wind temperature throughout the inner heliosphere clearly demonstrate increased values compared to simple adiabatic expansion, indicating ongoing plasma heating as the solar wind fills the solar system. Understanding and quantifying the heating mechanisms is a central question of heliophysics. We review the physical mechanisms of plasma heating and the necessity of accurately calibrated measurements. Our active research shows that various heating mechanisms, such as non-linear Stochastic Heating, quasi-linear Landau damping, and linear Cyclotron Heating, that transfer energy from waves to particles, work in unison with various plasma instabilities that release the energy from particles to waves, stopping the plasma from containing excess non-thermal energy. As the plasma particles approach Earth, their thermalization forms a terrestrial shock that further determines the behavior of the lower layers, from the magnetosphere to the ionosphere and below. During extreme space weather events, the solar wind plasma delivers substantial amounts of energy deeply into the atmosphere, creating potentially hazardous events. The macroscopic conditions of solar wind propagation and heating are well regulated by the microscopic processes at the spatial scales of the ion and electron gyrations and electrostatic motions. We also present novel experimental applications of efficient methods to advance observation technology the ionosphere, increasing data availability of the energy flow in this region through the installation of many instruments on small satellites.