Energy conversion through various channels in turbulent plasmas induced by the Kelvin-Helmholtz instability at the Earth’s magnetopause
Presentation Type
Talk
Presenter Format
Virtual Meeting Talk
Topic
Fundamental Processes in Comparative Magnetospheres
Start Date
13-5-2022 2:00 PM
Abstract
Energy conversion in collisionless plasmas is central to the plasma heating and particle energization problems in space and astrophysical plasmas, which remain unsolved nowadays. Though it is known that the electromagnetic energy is converted to the flow and random kinetic energy (via J.E), a detailed understanding of how the electromagnetic energy is converted into particle energy and finally dissipated to heat is still lacking. Motivated by the rich physics of Kelvin-Helmholtz (KH) waves, we consider energy conversion in turbulent plasmas induced by the KH instability at the Earth’s magnetopause. With observations from the Magnetospheric Multiscale mission, we consider the energy conversion from (1) the electromagnetic fields into the flow and (2) from the flow into thermal energy for each plasma species through the pressure work (via P.∇.v). We find that the KH vortex regions, where the magnetospheric and magnetosheath plasmas mix, are the key sites of energy conversion activities. Considering the accumulation of the energy conversion through various channels with time, we find that the accumulated energy conversion rate through the electromagnetic channel constantly increases. However, the accumulated energy conversion rate through the pressure work channel only increases when the KH waves reach the nonlinear stage of development. Moreover, while the energy conversion between flow and heat via P.∇.v is very dynamic for electrons, we find that the main contribution, which finally dissipates the flow energy into heat, comes from ions. By separating the contributions of J.E and P.∇.v into multiple terms, we will discuss kinetic processes that are likely responsible for the energy conversion. We will also discuss the partitioning of energy conversion through the different channels for each species. This work paves the way towards an understanding of energy transfer across scales in turbulent plasmas as mediated by magnetopause KH waves.
Energy conversion through various channels in turbulent plasmas induced by the Kelvin-Helmholtz instability at the Earth’s magnetopause
Energy conversion in collisionless plasmas is central to the plasma heating and particle energization problems in space and astrophysical plasmas, which remain unsolved nowadays. Though it is known that the electromagnetic energy is converted to the flow and random kinetic energy (via J.E), a detailed understanding of how the electromagnetic energy is converted into particle energy and finally dissipated to heat is still lacking. Motivated by the rich physics of Kelvin-Helmholtz (KH) waves, we consider energy conversion in turbulent plasmas induced by the KH instability at the Earth’s magnetopause. With observations from the Magnetospheric Multiscale mission, we consider the energy conversion from (1) the electromagnetic fields into the flow and (2) from the flow into thermal energy for each plasma species through the pressure work (via P.∇.v). We find that the KH vortex regions, where the magnetospheric and magnetosheath plasmas mix, are the key sites of energy conversion activities. Considering the accumulation of the energy conversion through various channels with time, we find that the accumulated energy conversion rate through the electromagnetic channel constantly increases. However, the accumulated energy conversion rate through the pressure work channel only increases when the KH waves reach the nonlinear stage of development. Moreover, while the energy conversion between flow and heat via P.∇.v is very dynamic for electrons, we find that the main contribution, which finally dissipates the flow energy into heat, comes from ions. By separating the contributions of J.E and P.∇.v into multiple terms, we will discuss kinetic processes that are likely responsible for the energy conversion. We will also discuss the partitioning of energy conversion through the different channels for each species. This work paves the way towards an understanding of energy transfer across scales in turbulent plasmas as mediated by magnetopause KH waves.
Comments
This work is partially supported by grant RTA6280002 from Thailand Science Research and Innovation.