ASTROMULTISCALE · Multiscale dynamics of astrophysical plasmas: pressure-anisotropy-driven instabilities and large-scale dynamical processes
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2015-06-01 → 2017-05-31
- EU contribution
- €195,455
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
Lines connect the coordinator with its partners.
Results in brief
Multiscale dynamics of astrophysical plasmas: pressure-anisotropy-driven instabilities and large-scale dynamical processes
The project focuses on dynamical processes in plasmas, consisting of ionized atoms and electrons, which are dynamically sensitive to magnetic fields and may change the magnetic fields by their motion. The complexity of the interaction of plasma particles and the electromagnetic field leads to difficulties in effective mathematical description and physical understanding of plasma dynamics. The primary purpose of the project is deeper understanding of processes related to development of the pressure anisotropy in collisionless or weakly collisional plasmas. The pressure anisotropy can be spontaneously generated by velocity shear, plasma expansion or compression and temperature gradients when characteristic time scale for these processes is smaller than the time scale for Coulomb collisions. Results of the project are expected to be important for general plasma physics as related to the problem of multiscale phenomena in plasmas and coupling between microphysics and macrophysical processes. The study falls into the field of fundamental research aiming at general understanding of pressure-anisotropy-related phenomena in plasmas with possible direct applications to other fields: dynamics of galaxy-cluster plasmas, dynamical processes in stellar winds and planetary magnetospheres. Due to numerous practical applications of plasmas, results of the project potentially may have some practical applications in future. In terms of objectives, the project focuses on the investigation of (i) the transfer of the energy between the components: kinetic (mechanical), thermal and magnetic, in the presence of pressure anisotropy and related instabilities, (ii) constraints on the pressure anisotropy and other variables describing the state of the system, (iii) development of computational tools for numerical simulations of pressure-anisotropic plasmas. The study includes links between the microphysics and large-scale dynamics and the role of instabilities and effective viscosity of pressure-anisotropic plasmas. Theoretical results are contrasted with spacecraft measurements in turbulent solar wind.
Data: CORDIS, © European Union
Project objective
The primary purpose of the proposed project is a deeper understanding of instabilities in plasmas and their influence on transport phenomena and large-scale dynamical processes. The studies will be focused on nonlinear regime of development of the firehose and mirror instabilities triggered by pressure anisotropy spontaneously generated in stellar-wind environments by large-scale expansion/compression effects and plasma turbulence. Recent studies of microphysics of the instabilities have provided systematic knowledge on saturation effects in nonlinear regime and related wave-particle interactions. This opens a possibility of investigation of a feedback between the microphysics and large-scale dynamics. The project is anticipated to provide answers to the questions: what is the effective collisionality of a pressure-anisotropic plasma that is unstable or marginally stable to the firehose and mirror instabilities and how does it change the effective pressure tensor (viscous stress) used in fluid description of plasmas?Results of the project are expected to be important for general plasma physics as related to the problem of multiscale phenomena in plasmas and coupling between microphysics and macrophysical processes. In particular, the results can help in better understanding of the dynamics of galaxy cluster plasmas, dynamical processes in stellar winds and planetary magnetospheres.The studies will be done by numerical simulations using state-of-the-art kinetic and fluid models of plasma dynamics. A numerical setup will be developed analogous to experimental setups used for classical viscosity measurements in fluids. This virtual setup will be used to measure stresses caused by development of instabilities in plasmas. A related problem of thermalization of microinstabilities into kinetic waves cascade will be also investigated. The entire modeling framework will be validated by comparison of simulation results with spacecraft measurements in turbulent solar wind.
Original text from CORDIS.
Participants
- THE CHANCELLOR, MASTERS AND SCHOLARS OF THE UNIVERSITY OF OXFORD · OxfordCoordinatorUnited Kingdom
Links
Data: CORDIS, © European Union