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Turbulence and Fusion (2015/2016)

Organizers: PF Claude Bardos (ICP & U. Paris), Uriel Frisch (Obs. Nice), Matthew Kunz (Princeton), Alex Schekochihin (Oxford), PF Arkady Tsinober (Tel Aviv Univ.)

Talks


Abel, Ian (Princeton) WPI Seminar Room 08.135 Mon, 20. Jul 15, 10:00
Multiscale kinetic edge models
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Hammett, Greg (Princeton PPL) WPI Seminar Room 08.135 Mon, 20. Jul 15, 16:15
Progress towards continuum gyrokinetic simulations of the edge region
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Mandell, Noah (Princeton) WPI Seminar Room 08.135 Tue, 21. Jul 15, 10:00
New gyrofluid closures, hybrid gyrofluid simulations with gyrokinetic zonal flows, Trinity/GryfX coupling, etc.
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Citrin, Jonathan (CEA/DIFFER) WPI Seminar Room 08.135 Tue, 21. Jul 15, 16:15
New approach for realtime capable and first-principle based transport modelling
A real-time capable core turbulence tokamak transport model is developed. This model is constructed from the regularized nonlinear regression of quasilinear gyrokinetic transport code output. The regression is performed with a multilayer perceptron neural network. The transport code input for the neural network training set consists of five dimensions, and is limited to adiabatic electrons. The neural network model successfully reproduces transport fluxes predicted by the original quasilinear model, while gaining five orders of magnitude in computation time. The model is implemented in a real-time capable tokamak simulator, and simulates a 300s ITER discharge in 10s. This proof-of-principle for regression based transport models anticipates a significant widening of input space dimensionality and physics realism for future training sets. This aims to provide unprecedented computational speed coupled with first-principle based physics for real-time control and integrated modelling applications.
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Waelbroek, Francois (IFS, UT Austin) WPI Seminar Room 08.135 Wed, 22. Jul 15, 10:00
Magnetic islands and Hamiltonian gyrofluid models
A Lie- Poisson bracket is presented for a four-field gyrofluid model with compressible ions and magnetic field curvature, thereby showing the model to be Hamiltonian. In particular, we find that in addition to commonly adopted magnetic curvature terms present in the continuity equations, analogous terms must be retained also in the momentum equations, in order to have a Lie-Poisson structure. The corresponding Casimir invariants are presented, and shown to be associated to four Lagrangian invariants, that get advected by appropriate ''velocity'' fields during the dynamics. This differs from a cold ion limit, in which the Lie-Poisson bracket transforms into the sum of direct and semidirect products, leading to only three Lagrangian invariants.
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Citrin, Jonathan (CEA/DIFFER) WPI Seminar Room 08.135 Thu, 23. Jul 15, 10:00
Overview and open questions on electromagnetic effects on tokamak transport
The impact of electromagnetic stabilization and flow shear stabilization on ITG turbulence is investigated. Analysis of a low-β JET L-mode discharge illustrates the relation between ITG stabilization and proximity to the electromagnetic instability threshold. This threshold is reduced by suprathermal pressure gradients, highlighting the effectiveness of fast ions in ITG stabilization. Extensive linear and nonlinear gyrokinetic simulations are then carried out for the high-β JET hybrid discharge 75225, at two separate locations at inner and outer radii. It is found that at the inner radius, nonlinear electromagnetic stabilization is dominant and is critical for achieving simulated heat fluxes in agreement with the experiment. The enhancement of this effect by suprathermal pressure also remains significant. It is also found that flow shear stabilization is not effective at the inner radii. However, at outer radii the situation is reversed. Electromagnetic stabilization is negligible while the flow shear stabilization is significant. These results constitute the high-β generalization of comparable observations found at low-β at JET. This is encouraging for the extrapolation of electromagnetic ITG stabilization to future devices. An estimation of the impact of this effect on the ITER hybrid scenario leads to a 20% fusion power improvement.
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Hammett, Greg (Princeton PPL) WPI Seminar Room 08.135 Thu, 23. Jul 15, 16:15
Lithium vapour boxes
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Wilkie, Georg (Maryland) WPI Seminar Room 08.135 Fri, 24. Jul 15, 10:00
Coupled radius-energy transport of alpha particles in GK turbulence
To rigorously model fast ions in fusion plasmas, a non-Maxwellian equilibrium distribution must be used. In this work, the response of high-energy alpha particles to electrostatic turbulence has been analyzed for several different tokamak parameters. Our results are consistent with known scalings and experimental evidence that alpha particles are generally well confined: on the order of several seconds. It is also confirmed that the effect of alphas on the turbulence is negligible at realistically low concentrations, consistent with linear theory. It is demonstrated that the usual practice of using a high-temperature Maxwellian, while previously shown to give an adequate order-of-magnitude estimate of the diffusion coefficient, gives incorrect estimates for the radial alpha particle flux, and a method of correcting it in general is provided. Furthermore, we see that the timescales associated with collisions and transport compete at moderate energies, calling into question the assumption that alpha particles remain confined to a flux surface that is used in the derivation of the slowing-down distribution.
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Roberg-Clark, Gareth (Maryland) WPI Seminar Room 08.135 Mon, 27. Jul 15, 10:00
Heat-flux driven instabilities in high-beta plasmas and their relevance for AGN feedback in galaxy clusters
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Catto, Peter (MIT) WPI Seminar Room 08.135 Mon, 27. Jul 15, 16:15
Three dimensional magnetized and rotating hot plasma equilibria in a gravitational field
A rotating and magnetized three-dimensional axisymmetric equilibrium for hot plasma confined by a gravitational field is found. The plasma density and current can exhibit strong equatorial plane localization, resulting in disk equilibria with open magnetic field lines. The associated equatorial plane pinching results in magnetic field flaring, implying a strong gravitational squeezing of the plasma carrying ambient magnetic field lines toward the gravitational source. At high plasma pressure, the magnetic field becomes strongly radial outside the disk. The model predicts the rotation frequency bound, the condition for a plasma disk, and the requirement for strong magnetic field flaring.
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Quataert, Eliot (Berkeley) WPI Seminar Room 08.135 Tue, 28. Jul 15, 10:00
Sheared electron kinetics: whistler and mirror instabilities
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Spitovsky, Anatoly (Princeton) WPI Seminar Room 08.135 Tue, 28. Jul 15, 16:15
Magnetogenesis in collisionless shear flows
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Komarov, Sergey (MPA Garching) WPI Seminar Room 08.135 Wed, 29. Jul 15, 10:00
Suppression of thermal conductivity by mirror fields
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Schekochihin, Alex (Oxford) WPI Seminar Room 08.135 Thu, 30. Jul 15, 10:00
Phase mixing vs. nonlinear advection in drift-kinetic plasma turbulence
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Kunz, Matt (Princeton) WPI Seminar Room 08.135 Thu, 30. Jul 15, 16:15
Firehose and mirror: old and new results
Hybrid-kinetic numerical simulations of firehose and mirror instabilities in a collisionless plasma are performed in which pressure anisotropy is driven as the magnetic field is changed by a persistent linear shear S . For a decreasing field, it is found that mostly oblique firehose fluctuations grow at ion Larmor scales and saturate with energies ∝S 1/2 ; the pressure anisotropy is pinned at the stability threshold by particle scattering off microscale fluctuations. In contrast, nonlinear mirror fluctuations are large compared to the ion Larmor scale and grow secularly in time; marginality is maintained by an increasing population of resonant particles trapped in magnetic mirrors. After one shear time, saturated order-unity magnetic mirrors are formed and particles scatter off their sharp edges. Both instabilities drive sub-ion-Larmor–scale fluctuations, which appear to be kinetic-Alfvén-wave turbulence. Our results impact theories of momentum and heat transport in astrophysical and space plasmas, in which the stretching of a magnetic field by shear is a generic process.
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

Dorland, Bill (Maryland) WPI Seminar Room 08.135 Fri, 31. Jul 15, 10:00
Turbulent dissipation challenge: what ought to be done
Many naturally occurring and man-made plasmas are collisionless and turbulent. It is not yet well understood how the energy in fields and fluid motions is transferred into the thermal degrees of freedom of constituent particles in such systems. The debate at present primarily concerns proton heating. Multiple possible heating mechanisms have been proposed over the past few decades, including cyclotron damping, Landau damping, heating at intermittent structures and stochastic heating. Recently, a community-driven effort was proposed (Parashar & Salem, 2013, arXiv:1303.0204) to bring the community together and understand the relative contributions of these processes under given conditions. In this paper, we propose the first step of this challenge: a set of problems and diagnostics for benchmarking and comparing different types of 2.5D simulations. These comparisons will provide insights into the strengths and limitations of different types of numerical simulations and will help guide subsequent stages of the challenge.
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: 8th Plasma Kinetics Working Group Meeting (2015)

WPI Seminar Room 08.135 Mon, 7. Dec 15, 14:20
Opening of Workshop
and self presentation of participants (5 min each)
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Vlasov-Poisson equations for plasmas and cosmology" (2015)

WPI Seminar Room 08.135 Mon, 7. Dec 15, 14:30
Presentation of participants
  • Thematic program: Turbulence and Fusion (2015/2016)

Besse, Nicolas (Obs. Nice & UCA) WPI Seminar Room 08.135 Mon, 7. Dec 15, 15:30
"On the eigenvalue problem for the gyrokinetic equations"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Vlasov-Poisson equations for plasmas and cosmology" (2015)

Colombi, Stephane (IAP & CNRS) WPI Seminar Room 08.135 Tue, 8. Dec 15, 9:30
"Evolution of collisionless, initially cold, self-gravitating Systems in one dimension"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Vlasov-Poisson equations for plasmas and cosmology" (2015)

Sousbie, Thierry (IAP & CNRS) WPI Seminar Room 08.135 Tue, 8. Dec 15, 11:00
"ColDICE: a parallel Vlasov-Poisson solver using moving adaptive simplicial tessellation"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Vlasov-Poisson equations for plasmas and cosmology" (2015)

Sobolevski, Andrei + Frisch, Uriel (Obs. Nice & CNRS) + Besse, Nicolas (Obs. Nice & UCA) WPI Seminar Room 08.135 Tue, 8. Dec 15, 12:00
"Work in Progress on Lagrangian time-analyticity of the Vlasov-Poisson flow"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Vlasov-Poisson equations for plasmas and cosmology" (2015)

Hahn, Oliver (Obs. Nice & UNS) WPI Seminar Room 08.135 Tue, 8. Dec 15, 14:40
"Cosmic structure formation in the continuum limit"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Vlasov-Poisson equations for plasmas and cosmology" (2015)

Gerard-Varet, David (U. Paris 7) WPI Seminar Room 08.135 Wed, 9. Dec 15, 9:30
"Trend to equilibrium in the Kuramoto model"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Vlasov-Poisson equations for plasmas and cosmology" (2015)

Bardos, Claude (WPI & ICP c/o Paris 6 & 7) WPI Seminar Room 08.135 Wed, 9. Dec 15, 11:00
"About the Maxwell Boltzmann equation"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Vlasov-Poisson equations for plasmas and cosmology" (2015)

Hauray, Maxime (U. AMU) WPI Seminar Room 08.135 Wed, 9. Dec 15, 12:00
"Weak-strong stability and mean-field limit for Vlasov equations"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Vlasov-Poisson equations for plasmas and cosmology" (2015)

Diamond, Patrick (UCSD) WPI Seminar Room 08.135 Wed, 9. Dec 15, 14:30
"The quasilinear theory for the Vlasov plasma dynamics: content, success, failures"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Vlasov-Poisson equations for plasmas and cosmology" (2015)

Han-Kwan, Daniel (Ecole Polytechnique & CNRS) WPI Seminar Room 08.135 Thu, 10. Dec 15, 11:00
"Quasineutral limit for Vlasov-Poisson: a review"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Vlasov-Poisson equations for plasmas and cosmology" (2015)

Brenier, Yann (Ecole Polytechnique & CNRS) WPI Seminar Room 08.135 Thu, 10. Dec 15, 14:30
"A double large deviation principle for the gravitational Vlasov-Poisson system via Monge-Ampere approximation"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Vlasov-Poisson equations for plasmas and cosmology" (2015)

Jabin, Pierre-Emmanuel (U. Maryland) WPI Seminar Room 08.135 Fri, 11. Dec 15, 10:00
"Mean field limits for bounded force kernels"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Vlasov-Poisson equations for plasmas and cosmology" (2015)

Ning, Jiang (U. Wuhan) WPI Seminar Room 08.135 Fri, 11. Dec 15, 14:30
"Boundary layers and the fluid limits of the Boltzmann equation"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Vlasov-Poisson equations for plasmas and cosmology" (2015)

WPI Seminar Room 08.135 Mon, 14. Dec 15, 14:20
Opening of Workshop
and self presentation of participants
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Gibbon, John (Imperial College London) WPI Seminar Room 08.135 Mon, 14. Dec 15, 15:00
“Regimes of nonlinear depletion and regularity in the 3D Navier-Stokes equations”
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Dong, Li (U. British Colombia) WPI Seminar Room 08.135 Mon, 14. Dec 15, 15:45
"Ill posedness of the Euler Equation in Cm and related issues"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Wiedemann, Emil (U. Bonn) WPI Seminar Room 08.135 Mon, 14. Dec 15, 16:30
"The issue of weak-strong uniqueness in contrast to non-uniqueness for 'wild' solutions"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Vicol, Vlad (U. Princeton) WPI Seminar Room 08.135 Tue, 15. Dec 15, 10:00
"Remarks on the vanishing viscosity problem with Dirichlet boundary conditions"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Dalibard, Anne-Laure (U. Paris 6) WPI Seminar Room 08.135 Tue, 15. Dec 15, 11:00
"Separation for the stationary Prandle equation"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Mazzucato, Anna (U. Penn State) WPI Seminar Room 08.135 Tue, 15. Dec 15, 14:30
"The vanishing viscosity limit in the presence of a porous medium"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Nguyen, Toan (U. Penn State) WPI Seminar Room 08.135 Tue, 15. Dec 15, 15:30
"The stability of boundary layers: an overview"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Frisch, Uriel (Obs. Nice & CNRS) WPI Seminar Room 08.135 Wed, 16. Dec 15, 10:00
"The Cauchy-Lagrangian method for numerical analysis of Euler Flow"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Besse, Nicolas (Obs. Nice & UCA) WPI Seminar Room 08.135 Wed, 16. Dec 15, 11:00
"Time-analyticity of Lagrangian incompressible Euler flow in a bounded Domain"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Kukavica, Igor (U. Southern California) WPI Seminar Room 08.135 Wed, 16. Dec 15, 14:30
"Analyticity results for the incompressible Euler equations "
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Brenier, Yann (Ecole Polytechnique & CNRS) WPI Seminar Room 08.135 Wed, 16. Dec 15, 15:30
"Rearrangement methods in convective and compressible fluid motions"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Boldrighini, Carlo (U. Rome) WPI Seminar Room 08.135 Thu, 17. Dec 15, 10:00
"Li-Sinai solutions of the 3-d Navier-Stokes equations and related real solutions: theory and computer simulations"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Szekelyhidi, Laszlo (U. Leipzig) WPI Seminar Room 08.135 Thu, 17. Dec 15, 11:00
"Hölder continuous weak solutions of the Euler equations"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Mucha, Piotr (U. Warsaw) WPI Seminar Room 08.135 Thu, 17. Dec 15, 14:30
"Slightly compressible Navier-Stokes system connection to incompressible flows"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Li, Jinkai (U. Weizmann) WPI Seminar Room 08.135 Thu, 17. Dec 15, 15:30
"Recent advances on the primitive equations of oceanic and atmospheric dynamics"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Hittmeir, Sabine (U. Vienna) WPI Seminar Room 08.135 Fri, 18. Dec 15, 10:00
"Multiscale asymptotics and analysis for atmospheric flow models with moisture"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

Constantin, Peter (U. Princeton) WPI Seminar Room 08.135 Fri, 18. Dec 15, 11:00
"Nonlocal equations in bounded Domains"
  • Thematic program: Turbulence and Fusion (2015/2016)
  • Event: Workshop on "Euler and Navier-Stokes Equations and Connected Topics" (2015)

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