Workshop on Cross-Scale Coupling in Plasmas

Plasma turbulence has a highly complex, non-linear and multi-scale nature covering a vast range of scales, from inter-galactic to below the electron gyroradius. It is observed in a number of dramatically different regimes, from laboratory and fusion devices, to solar and astrophysical systems. Within space plasmas, it is found in the solar wind, where turbulence is well developed and energy inputs are steady; and in the highly disturbed magnetosheath, where fluctuations are highly driven by shocks and compressions. Also, numerical simulations in different regimes (MHD, kinetic scales) are used in an attempt to understand and describe such systems. In this session we welcome contributions that address fundamental properties of the plasma turbulence and that can help to obtain the best experimental data set to fundamentally advance those topics. A special emphasys will be given to the cross-scale properties of turbulence.

Collisionless plasma shocks are some of the most spectacular, visually striking and energetic events in the Universe. Even modest Mach number shocks are fundamentally variable in time and space. They exhibit reformation, a quasi-periodic variation in the shock profile, in addition to intrinsic spatial and temporal variations of phenomena at all scales. It is essential to study these variations simultaneously on electron, ion and fluid scales to measure the interactions between physical processes which occur within shocks, and how these produce their large scale effects. This session will discuss current observational and theoretical understanding of shocks in various plasmas from laboratories to near-Earth space to the distant regions of the Universe to identify key processes and parameters that are needed to answer fundamental questions, including: How do shocks accelerate particles? How is incident energy partitioned by the shock? How do shocks respond to changes in the upstream plasma?

Magnetic reconnection is a fundamental plasma physics process which breaks down the barriers between neighbouring plasmas, releasing energy from their magnetic fields, transferring material and momentum between those plasmas, and accelerating charged particles to high energies. The Universe is filled with systems in which reconnection is expected to play significant roles in their dynamical evolution, including stellar and planetary systems at all stages of their life cycles. Many observations have provided evidence that reconnection does indeed occur in space and coronal plasmas. However, uncertainty remains in the conditions needed to initiate and maintain reconnection, although processes occurring on small scales, comparable to ion and electron gyroradii, are known to play key roles. In turn, these localised processes couple into the global scale with consequences for the dynamics of the entire plasma system. In this session we solicit contributions exploring, comparing and contrasting the role of reconnection in different plasma regimes (astrophysical, solar, magnetospheric, laboratory, etc.). We seek to examine current understanding of the controlling influences on reconnection in different environments, and to discuss measurements needed to help resolve the most important unanswered questions.