Turbulent Mixing and Beyond Workshop

Goals and Scope

"Mixing in Fusion Plasmas" has been organized as the invited mini-conference at the 55th Annual Meeting of the American Physical Society Division of Plasma Physics. The three sessions of the mini-conference has united scientists working in the areas of plasma fusion, fluid turbulence, and mixing.

Mixing and turbulent mixing plays an important role in fusion plasmas. For instance, Rayleigh-Taylor (RT) mixing is a central concern for in achieving ignition in Inertial Confinement Fusion due to the occurrence of Rayleigh-Taylor instabilities (RTI) at the stages of shock acceleration, steady acceleration and decelerations of the implosion, and also due to additional seeding of RTI by the imperfections drive and the target. RT mixing is also known to limit radial compression of imploding Z-pinches. Somewhat similar processes strongly affect the plasma transport in magnetic and heavy-ion fusion. While in fusion environments the mixing process should be mitigated, in some other applications of high energy density plasmas, for instance, in high energy density laboratory astrophysics, mixing and turbulent should be enhanced. In all these circumstances, understanding the fundamentals of mixing process is necessary to achieve a better control of the fusion.

Mixing processes are difficult to study. Usually they involve sharp changes of the flow fields, strong pressures and accelerations, and very strong magnetic fields. They are inhomogeneous (i.e., the flow fields are essentially non-uniform, even in statistical sense, and may involve fronts), anisotropic (i.e., their dynamics depends on the directions), non-local (i.e., the plasma flow depends on the initial conditions and on the contributions from all the scales), and statistically unsteady (i.e., mean values of the quantities vary with time, and there are also time-dependent fluctuations around these means). Their properties often strongly deviate from those prescribed by standard scenarios, such as canonical turbulence at macroscopic scales or local thermodynamic equilibrium at microscopic scales.

Despite these challenges, significant success has been recently achieved in large-scale numerical simulations, in laboratory experiments (especially those in high power laser systems), in technology development (including possibilities for improvements in precision, dynamic range, reproducibility, accuracy, and data acquisition rate), and in theoretical analysis (for instance, new approaches for handling multi-scale, non-local and statistically unsteady transport). This opens new opportunities for the studies of fundamental properties of mixing and turbulent mixing in fusion plasmas.

The mini-conference has provided the opportunity to bring together scientists from different areas of fusion, including inertial confinement, magnetic fusion and Z-pinches, as well as key experts in fluid dynamics, astrophysics, and applied mathematics. It will be structured to encourage participants’ communications with experts from various fields, to promote the exchange of ideas, and to motivate the discussions of rigorous mathematical issues, theoretical approaches and state-of-the-art numerical simulations along with advanced experimental techniques and technological applications.

The mini-conference participants included leading experts and researchers at experienced and early stages of their carriers from academia and national laboratories.