Energy budget in the turbulent terrestrial magnetosheath

The terrestrial magnetosphere is a region of space where the magnetic field influences the motion of energetic charged particles of solar or cosmic origin. The magnetosphere also acts as an obstacle that deflects the solar wind, a supersonic, electrically conducting plasma flow emitted from the Sun. As a result of this interaction, a shock wave forms upstream of the magnetosphere, where the plasma is decelerated and heated. Between the shock and the magnetosphere, there is a highly turbulent region called the magnetosheath. In such a complex plasma environment, different forms of energies must be studied, namely electromagnetic, kinetic, and thermal energies. These energies can be transferred between physical scales (e.g., from large scales to small scales), transported between locations (e.g., from location A to location B), or converted between each other (e.g., kinetic energy to heat or thermal energy). The theoretically predicted energy terms can be calculated from existing Cluster and MMS mission data, by using four point spatial measurements of field and plasma parameters along the spacecraft trajectories in the terrestrial magnetosheath. Since the inter-spacecraft distances of Cluster and MMS differ, and both missions cross the magnetosheath at different regions and times, the energy terms can be statistically evaluated across various locations, scales, and solar wind driving conditions. According to numerical simulations the energy terms are scale dependent. Simulations also predict that the energy conversions are not space filling but rather locally concentrated at narrow coherent structures, where the available free energy can affect particle populations and their velocity distributions. This can generate instabilities and waves including various wave particle interactions and changes in velocity distributions of particles. By using MMS data, the kinetic scale processes associated with the changing velocity distributions of particles and their relation to multi-scale energy terms at coherent structures can be better understood, locally and statistically. We will conduct extended statistical analyses based on advanced statistical methods by using single- and multi-point measurements, testing simulation results through the fluid- and kinetic-scale Cluster and MMS data. The near-Earth plasma environment is the only space region where these fundamental processes can be probed directly by the presently available spacecraft measurements. The expected results can shape our understanding of energy exchanges and dissipation in collisionless space plasmas. Additionally, the role of the active magnetosheath in solar wind magnetosphere interaction processes can be better understood.