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Models in Plasmas, Earth and Space Science (2017/2018)

Organizers: PF Claude Bardos (ICP and U. Paris), Ludovic Ferrière (NHM Wien), PF Uriel Frisch (Obs. Nice), Sabine Hittmeir (U. Wien), Matthew Kunz (Princeton), Adi Nusser (Technion Haifa), Alex Schekochihin (Oxford), Edriss Titi (UC San Diego and Weizmann)

Talks


Elizabeth Paul (Maryland) WPI, OMP 1, Seminar Room 08.135 Mon, 17. Jul 17, 10:00
Rotation and Neoclassical Ripple Transport in ITER
Neoclassical transport in the presence of non-axisymmetric magnetic fields causes a toroidal torque known as neoclassical toroidal viscosity (NTV). The toroidal symmetry of ITER will be broken by the finite number of toroidal field coils and by test blanket modules (TBMs). The addition of ferritic inserts (FIs) will decrease the magnitude of the toroidal field ripple. 3D magnetic equilibria in the presence of toroidal field ripple and ferromagnetic structures are calculated for an ITER steady-state scenario using the Variational Moments Equilibrium Code (VMEC). Neoclassical transport quantities in the presence of these error fields are calculated using the Stellarator Fokker-Planck Iterative Neoclassical Conservative Solver (SFINCS). These calculations fully account for E r , flux surface shaping, multiple species, magnitude of ripple, and collisionality rather than applying approximate analytic NTV formulae. As NTV is a complicated nonlinear function of E r , we study its behavior over a plausible range of E r . We estimate the toroidal flow, and hence E r , using a semi-analytic turbulent intrinsic rotation model and NUBEAM calculations of neutral beam torque. The NTV torque due to TF ripple without ferritic components is found to be comparable in magnitude to the turbulent and NBI torques, though their radial profiles differ. The NTV from the |n|=18 ripple dominates that from lower n perturbations of the TBMs. With the inclusion of FIs, the magnitude of NTV torque is reduced by about 75% near the edge. We present comparisons of several models of tangential magnetic drifts on superbanana-plateau transport at small E r , and we consider the scaling of calculated NTV torque with ripple magnitude.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Iván Calvo (CIEMAT) WPI, OMP 1, Seminar Room 08.135 Mon, 17. Jul 17, 16:00
The effect of tangential drifts on neoclassical transport in stellarators close to omnigeneity
In general, the orbit-averaged radial magnetic drift of trapped particles in stellarators is non-zero due to the three-dimensional nature of the magnetic field. Stellarators in which the orbit-averaged radial magnetic drift vanishes are called omnigeneous, and they exhibit neoclassical transport levels comparable to those of axisymmetric tokamaks. However, the effect of deviations from omnigeneity cannot be neglected in practice, and it is more deleterious at small collisionalities. For sufficiently low collision frequencies (below the values that define the $1/nu $ regime), the components of the drifts tangential to the flux surface become relevant. This article focuses on the study of such collisionality regimes in stellarators close to omnigeneity when the gradient of the non-omnigeneous perturbation is small. First, it is proven that closeness to omnigeneity is required to actually preserve radial locality in the drift-kinetic equation for collisionalities below the $1/nu $ regime. Then, using the derived radially local equation, it is shown that neoclassical transport is determined by two layers located at different regions of phase space. One of the layers corresponds to the so-called $sqrt{nu }$ regime and the other to the so-called superbanana-plateau regime. The importance of the superbanana-plateau layer for the calculation of the tangential electric field is emphasized, as well as the relevance of the latter for neoclassical transport in the collisionality regimes considered in this paper. In particular, the role of the tangential electric field is essential for the emergence of a new subregime of superbanana-plateau transport when the radial electric field is small. A formula for the ion energy flux that includes the $sqrt{nu }$ regime and the superbanana-plateau regime is given. The energy flux scales with the square of the size of the deviation from omnigeneity. Finally, it is explained why below a certain collisionality value the formulation presented in this article ceases to be valid.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Silvia Espinosa (MIT) WPI, OMP 1, Seminar Room 08.135 Tue, 18. Jul 17, 10:00
Pedestal radial flux measuring method to prevent impurity accumulation
The use of high-z wall materials attempts to shift the fusion challenge from heat handling to impurity removal. We demonstrate that not only the impurity density in-out asymmetry but also the poloidal flow has a major impact on the radial impurity flux direction. This realization provides the first method of measuring the flux from available diagnostics, without the need of a computationally demanding kinetic calculation of the full bulk ion response. Moreover, it affords insight into optimal tokamak operation to avoid impurity accumulation while allowing free fueling.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Alessandro Geraldini (Oxford) WPI, OMP 1, Seminar Room 08.135 Tue, 18. Jul 17, 16:00
Gyrokinetic treatment of a grazing angle magnetic presheath
We develop a gyrokinetic treatment for ions in the magnetic presheath, close to the plasma-wall boundary. We focus on magnetic presheaths with a small magnetic field to wall angle, $\alpha \ll 1$ (in radians). Characteristic lengths perpendicular to the wall in such a magnetic presheath scale with the typical ion Larmor orbit size, ${\rho }_{{\rm{i}}}$. The smallest scale length associated with variations parallel to the wall is taken to be across the magnetic field, and ordered $l={\rho }_{{\rm{i}}}/\delta $, where $\delta \ll 1$ is assumed. The scale lengths along the magnetic field line are assumed so long that variations associated with this direction are neglected. These orderings are consistent with what we expect close to the divertor target of a tokamak. We allow for a strong component of the electric field ${\bf{E}}$ in the direction normal to the electron repelling wall, with strong variation in the same direction. The large change of the electric field over an ion Larmor radius distorts the orbit so that it is not circular. We solve for the lowest order orbits by identifying coordinates, which consist of constants of integration, an adiabatic invariant and a gyrophase, associated with periodic ion motion in the system with $\alpha =\delta =0$. By using these new coordinates as variables in the limit $\alpha \sim \delta \ll 1$, we obtain a generalised ion gyrokinetic equation. We find another quantity that is conserved to first order and use this to simplify the gyrokinetic equation, solving it in the case of a collisionless magnetic presheath. Assuming a Boltzmann response for the electrons, a form of the quasineutrality equation that exploits the change of variables is derived. The gyrokinetic and quasineutrality equations give the ion distribution function and electrostatic potential in the magnetic presheath if the entrance boundary condition is specified.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Justin Ball (EPFLausanne) WPI, OMP 1, Seminar Room 08.135 Wed, 19. Jul 17, 10:00
Optimized up-down asymmetry to drive fast intrinsic rotation in tokamaks
Breaking the up-down symmetry of the tokamak poloidal cross-section can significantly increase the spontaneous rotation due to turbulent momentum transport. In this work, we optimize the shape of flux surfaces with both tilted elongation and tilted triangularity in order to maximize this drive of intrinsic rotation. Nonlinear gyrokinetic simulations demonstrate that adding optimally-tilted triangularity can double the momentum transport of a tilted elliptical shape. This work indicates that tilting the elongation and triangularity in an ITER-like device can reduce the energy transport and drive intrinsic rotation with an Alfv\'{e}n Mach number on the order of 1% . This rotation is four times larger than the rotation expected in ITER and is sufficient to stabilize MHD instabilities. It is shown that this optimal shape can be created using the shaping coils of several experiments.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Denis St-Onge (Princeton) WPI, OMP 1, Seminar Room 08.135 Wed, 19. Jul 17, 16:30
The Dimits Shift in a One-Field Fluid Model
The two-dimensional Terry-Horton equation is shown to exhibit the Dimits shift when suitably modified to capture both the nonlinear enhancement of zonal/drift-wave interactions and the existence of residual Rosenbluth-Hinton states. This phenomena persists through numerous simplifications of the equation, including a quasilinear approximation as well as a four-mode truncation. Analytic progress on the truncated system is reported, focused on determining the growth rates of zonal flows and calculating the upper bound of the Dimits shift. The results for the truncated system are then used to estimate the Dimits shift of the fully nonlinear system. A new understanding is thus developed on the fundamental nature of the Dimits shift, both on its operation and its eventual termination.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

David Hatch (UT Austin) WPI, OMP 1, Seminar Room 08.135 Thu, 20. Jul 17, 16:00
Flow Shear Suppression of Pedestal Turbulence--A First Principles Theoretical Framework
A combined analytic and computational gyrokinetic approach is developed to address the question of the scaling of pedestal turbulent transport with arbitrary levels of E×B shear. Due to strong gradients and shaping in the pedestal, the instabilities of interest are not curvature-driven like the core instabilities. By extensive numerical (gyrokinetic) simulations, it is demonstrated that pedestal modes respond to shear suppression very much like the predictions of a basic analytic decorrelation theory. The quantitative agreement between the two provides us with a new dependable, first principles (physics based) theoretical framework to predict the efficacy of shear suppression in burning plasmas that lie in a low-shear regime not accessed by present experiments.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Lev Arzamasskiy (Princeton) WPI, OMP 1, Seminar Room 08.135 Mon, 24. Jul 17, 10:00
Hybrid-kinetic simulations of solar wind turbulence
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Yohei Kawazura (Oxford) WPI, OMP 1, Seminar Room 08.135 Mon, 24. Jul 17, 10:30
Hybrid GK-isothermal electrons code + ion heating calculations
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Alex Schekochihin (Oxford) WPI, OMP 1, Seminar Room 08.135 Mon, 24. Jul 17, 16:00
MHD turbulence in 2017: end of the road? ++kinetic extensions
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Nuno Loureiro (MIT) WPI, OMP 1, Seminar Room 08.135 Mon, 24. Jul 17, 16:45
MHD turbulence + magnetic reconnection
The current understanding of magnetohydrodynamic (MHD) turbulence envisions turbulent eddies which are anisotropic in all three directions. In the plane perpendicular to the local mean magnetic field, this implies that such eddies become current-sheetlike structures at small scales. We analyze the role of magnetic reconnection in these structures and conclude that reconnection becomes important at a scale ¥ë¡­LS −4/7L, where SL is the outer-scale (L) Lundquist number and ¥ë is the smallest of the field-perpendicular eddy dimensions. This scale is larger than the scale set by the resistive diffusion of eddies, therefore implying a fundamentally different route to energy dissipation than that predicted by the Kolmogorov-like phenomenology. In particular, our analysis predicts the existence of the subinertial, reconnection interval of MHD turbulence, with the estimated scaling of the Fourier energy spectrum E(k¡Ñ)¡ðk−5/2¡Ñ, where k¡Ñ is the wave number perpendicular to the local mean magnetic field. The same calculation is also performed for high (perpendicular) magnetic Prandtl number plasmas (Pm), where the reconnection scale is found to be ¥ë/L¡­S−4/7LPm−2/7.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Francois Rincon (Toulouse) WPI, OMP 1, Seminar Room 08.135 Tue, 25. Jul 17, 10:00
Some thoughts on theoretical problems and appoaches in dynamo theory
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Nuno Loureiro (MIT) WPI, OMP 1, Seminar Room 08.135 Tue, 25. Jul 17, 16:00
Fully-kinetic versus reduced-kinetic modelling of collisionless plasma turbulence
Pulsed-power driven magnetic reconnection experiments
We report the results of a direct comparison between different kinetic models of collisionless plasma turbulence in two spatial dimensions. The models considered include a first principles fully-kinetic (FK) description, two widely used reduced models [gyrokinetic (GK) and hybrid-kinetic (HK) with fluid electrons], and a novel reduced gyrokinetic approach (KREHM). Two different ion beta (â i ) regimes are considered: 0.1 and 0.5. For â i =0.5 , good agreement between the GK and FK models is found at scales ranging from the ion to the electron gyroradius, thus providing firm evidence for a kinetic Alfv'en cascade scenario. In the same range, the HK model produces shallower spectral slopes, presumably due to the lack of electron Landau damping. For â i =0.1 , a detailed analysis of spectral ratios reveals a slight disagreement between the GK and FK descriptions at kinetic scales, even though kinetic Alfv'en fluctuations likely still play a significant role. The discrepancy can be traced back to scales above the ion gyroradius, where the FK and HK results seem to suggest the presence of fast magnetosonic and ion Bernstein modes in both plasma beta regimes, but with a more notable deviation from GK in the low-beta case. The identified practical limits and strengths of reduced-kinetic approximations, compared here against the fully-kinetic model on a case-by-case basis, may provide valuable insight into the main kinetic effects at play in turbulent collisionless plasmas, such as the solar wind.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Archie Bott (Oxford) WPI, OMP 1, Seminar Room 08.135 Wed, 26. Jul 17, 10:00
When are plasmas collisional?
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Jonathan Squire (Caltech) WPI, OMP 1, Seminar Room 08.135 Wed, 26. Jul 17, 16:00
Resonant instabilities: dust-gas coupling and others?
It is shown that grains streaming through a fluid are generically unstable if their velocity, projected along some direction, matches the phase velocity of a fluid wave. This can occur whenever grains stream faster than a fluid wave. The wave itself can be quite general--sound waves, magnetosonic waves, epicyclic oscillations, and Brunt-V\"ais\"al\"a oscillations each generate instabilities, for example. A simple expression for this "resonant drag instability" (RDI) growth rate is derived. This expression (i) illustrates why such instabilities are so virulent and generic, and (ii) allows for simple analytic computation of RDI growth rates and properties for different fluid systems. As examples, we introduce several new instabilities, which could see application across a variety of astrophysical systems from protoplanetary disks to galactic outflows.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Vladimir Zhdankin (UC Boulder) WPI, OMP 1, Seminar Room 08.135 Thu, 27. Jul 17, 10:00
Particle acceleration in relativistic kinetic turbulence
We present results from particle-in-cell simulations of driven turbulence in magnetized, collisionless, and relativistic pair plasmas. We find that the fluctuations are consistent with the classical k −5/3 ¡Ñ magnetic energy spectrum at fluid scales and a steeper k −4 ¡Ñ spectrum at sub-Larmor scales, where k¡Ñ is the wave vector perpendicular to the mean field. We demonstrate the development of a nonthermal, power-law particle energy distribution f(E)¡­E−¥á, with an index ¥á that decreases with increasing magnetization and increases with an increasing system size (relative to the characteristic Larmor radius). Our simulations indicate that turbulence can be a viable source of energetic particles in high-energy astrophysical systems, such as pulsar wind nebulae, if scalings asymptotically become insensitive to the system size.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Dmitri Uzdensky (UC Boulder) WPI, OMP 1, Seminar Room 08.135 Thu, 27. Jul 17, 10:30
Nonthermal particle acceleration in relativistic collisionless magnetic reconnection
As a fundamental process converting magnetic to plasma energy in high-energy astrophysical plasmas, relativistic magnetic reconnection is a leading explanation for the acceleration of particles to the ultrarelativistic energies necessary to power nonthermal emission (especially X-rays and gamma-rays) in pulsar magnetospheres and pulsar wind nebulae, coronae and jets of accreting black holes, and gamma-ray bursts. An important objective of plasma astrophysics is therefore the characterization of nonthermal particle acceleration (NTPA) effected by reconnection. Reconnection-powered NTPA has been demonstrated over a wide range of physical conditions using large two-dimensional (2D) kinetic simulations. However, its robustness in realistic 3D reconnection -- in particular, whether the 3D relativistic drift-kink instability (RDKI) disrupts NTPA -- has not been systematically investigated, although pioneering 3D simulations have observed NTPA in isolated cases. Here we present the first comprehensive study of NTPA in 3D relativistic reconnection in collisionless electron-positron plasmas, characterizing NTPA as the strength of 3D effects is varied systematically via the length in the third dimension and the strength of the guide magnetic field. We find that, while the RDKI prominently perturbs 3D reconnecting current sheets, it does not suppress particle acceleration, even for zero guide field; fully 3D reconnection robustly and efficiently produces nonthermal power-law particle spectra closely resembling those obtained in 2D. This finding provides strong support for reconnection as the key mechanism powering high-energy flares in various astrophysical systems. We also show that strong guide fields significantly inhibit NTPA, slowing reconnection and limiting the energy available for plasma energization, yielding steeper and shorter power-law spectra.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Denis St-Onge (Princeton) WPI, OMP 1, Seminar Room 08.135 Thu, 27. Jul 17, 16:00
Plasma dynamo
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Michael Medvedev (Kansas) WPI, OMP 1, Seminar Room 08.135 Fri, 28. Jul 17, 10:00
Quasi-nonlinear theory of the Weibel instability
Astrophysical and high-energy-density laboratory plasmas often have large-amplitude, sub-Larmor-scale electromagnetic fluctuations excited by various kinetic-streaming or anisotropy-driven instabilities. The Weibel (or the filamentation) instability is particularly important because it can rapidly generate strong magnetic fields, even in the absence of seed fields. Particles propagating in collisionless plasmas with such small-scale magnetic fields undergo stochastic deflections similar to Coulomb collisions, with the magnetic pitch-angle diffusion coefficient representing the effective "collision" frequency. We show that this effect of the plasma "quasi-collisionality" can strongly affect the growth rate and evolution of the Weibel instability in the deeply nonlinear regime. This result is especially important for understanding cosmic-ray-driven turbulence in an upstream region of a collisionless shock of a gamma-ray burst or a supernova. We demonstrate that the quasi-collisions caused by the fields generated in the upstream suppress the instability slightly but can never shut it down completely. This confirms the assumptions made in the self-similar model of the collisionless foreshock.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: 10th Plasma Kinetics Working Group Meeting (2017)

Rampf, Cornelius (U. Heidelberg) WPI, OMP 1, Seminar Room 08.135 Mon, 18. Dec 17, 14:00
Shell-crossing in quasi-one-dimensional flow
Blow-up of solutions for the cosmological fluid equations, often dubbed shell-crossing or orbit crossing, denotes the breakdown of the single-stream regime of the cold-dark-matter fluid. At this instant, the velocity becomes multi-valued and the density singular. Shell-crossing is well understood in one dimension (1D), but not in higher dimensions. This talk is about quasi-one-dimensional (Q1D) flow that depends on all three coordinates but differs only slightly from a strictly 1D flow, thereby allowing a perturbative treatment of shell-crossing using the Euler-Poisson equations written in Lagrangian coordinates. The signature of shell-crossing is then just the vanishing of the Jacobian of the Lagrangian map, a regular perturbation problem. In essence the problem of the first shell-crossing, which is highly singular in Eulerian coordinates, has been desingularized by switching to Lagrangian coordinates, and can then be handled by perturbation theory. All-order recursion relations are obtained for the time-Taylor coefficients of the displacement field, and it is shown that the Taylor series has an infinite radius of convergence. This allows the determination of the time and location of the first shell-crossing, which is generically shown to be taking place earlier than for the unperturbed 1D flow. The time variable used for these statements is not the cosmic time t but the linear growth time $tau sim t^{2/3}$. For simplicity, calculations are restricted to an Einstein-de Sitter universe in the Newtonian approximation, and tailored initial data are used. However it is straightforward to relax these limitations, if needed.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Vlasov-Poisson in cosmology and plasma physics: monokinetic and multi-beam/stream solutions" (2017)

Colombi, Stephane (I.Astrophysique Paris) WPI, OMP 1, Seminar Room 08.135 Mon, 18. Dec 17, 15:30
Phase-space structure of dark matter proto-halos: pre- and -post-collapse regimes
During this talk I'll discuss the formation of primordial dark matter halos from smooth initial conditions. To simplify furthermore the context, we shall consider structures seeded by 3 sine waves of various amplitudes. Phase-space evolution of these objects will be studied from the computational point of view, by using a state of the art Vlasov solver, and the theoretical point of view, by comparing the numerical results to predictions of Lagrangian perturbation theory. While these latter are in principle only calculable prior to collapse, extension to multi-streaming regime will be discussed, with actual implementation in the 1D cosmological case of "post-collapse" Lagrangian perturbation theory.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Vlasov-Poisson in cosmology and plasma physics: monokinetic and multi-beam/stream solutions" (2017)

Nguyen, Toan (U. Pennsylvania) WPI, OMP 1, Seminar Room 08.135 Tue, 19. Dec 17, 9:30
Long-time estimates for Vlasov-Maxwell in the non-relativistic limit
I will present a joint work with D. Han-Kwan and F. Rousset on establishing long time estimates for Vlasov-Maxwell systems near stable homogeneous equilibria, which are valid for times of an arbitrarily large polynomial order of the speed of light in the non-relativistic limit.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Vlasov-Poisson in cosmology and plasma physics: monokinetic and multi-beam/stream solutions" (2017)

Lesur, Maxime (U. Lorraine) WPI, OMP 1, Seminar Room 08.135 Tue, 19. Dec 17, 14:30
Plasma turbulence and transport dominated by nonlinear kinetic effects
In hot plasmas, collisions are so rare that microscopic vortex-like structures develop in the phase-space of the particle distribution: coupling both real space and velocity (or energy) space. In this work, we focus on magnetic confinement fusion plasmas (in toroidal geometry). We base our approach on a reduced kinetic model [1, 2], akin to the Vlasov-Poisson model. Our numerical simulations indicate the nonlinear self-organisation, within the turbulence, of fine-scale velocity-space (or energy-space) structures, which can drive most of the macroscopic radial transport in some regimes.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Vlasov-Poisson in cosmology and plasma physics: monokinetic and multi-beam/stream solutions" (2017)

Brenier, Yann (CNRS X Palaiseau): WPI, OMP 1, Seminar Room 08.135 Wed, 20. Dec 17, 9:30
On the MAK reconstruction method for the early universe
I will report on some very recent progress made on the MAK method for the numerical reconstruction of the early universe (in particular by Bruno Lévy and Jean-David Benamou), based either on the geometric algorithm of Mérigot for the Monge-Ampère equation or on the entropic regularization method (going back to Schrödinger in the 30s) for the optimal mass transport problem with quadratic cost.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Vlasov-Poisson in cosmology and plasma physics: monokinetic and multi-beam/stream solutions" (2017)

Gürcan, Özgür (U. PMC Paris) WPI, OMP 1, Seminar Room 08.135 Wed, 20. Dec 17, 14:30
Dynamics of a shell model of bounced averaged gyrokinetic Vlasov Equation
Development of a shell model for a bounced averaged gyrokinetic Vlasov equation is presented. First, the linear dynamics is compared with a linear solver based on solving the linear dispersion relation numerically. Then the nonlinear dynamics is studied by analyzing the wave-number spectrum of quadratic conserved quantities. The resulting spectra seems to show a cascade spectrum at high k and predator-prey like oscillations in low k. Future perspectives including a logarithmically discretized three dimensional version of the model, which is 2D in space and 1D in energy, is discussed.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Vlasov-Poisson in cosmology and plasma physics: monokinetic and multi-beam/stream solutions" (2017)

Diamond, Patrick (UC San Diego) WPI, OMP 1, Seminar Room 08.135 Thu, 21. Dec 17, 9:30
Quasi-Geostrophic Fluids and Vlasov Plasmas: Parallels and Intersections
This talk explores connections and contrasts between the nonlinear dynamics of two prototypical systems in plasmas and fluids. The first is the quasi-geostrophic fluid, which evolves by conservative advection of potential vorticity. The QG system is the minimal model for large-scale atmospheric waves and the jet stream (zonal flow). The second is the Vlasov–Poisson system, in which the Vlasov equation describes the conservative advection of a phase space density. Many interesting connections between these two systems already have been noted. This talk will expand the list and suggest directions for future cross-fertilization .
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Vlasov-Poisson in cosmology and plasma physics: monokinetic and multi-beam/stream solutions" (2017)

Uhlemann, Cora (U. Cambridge) WPI, OMP 1, Seminar Room 08.135 Thu, 21. Dec 17, 15:00
Finding closure - what Schrödinger-Poisson can teach us about cumulant hierarchies
Since dark matter almost exclusively interacts gravitationally, the dynamics of its phase space distribution is described by Vlasov-Poisson. One key property of Vlasov-Poisson is that it corresponds to an infinite tower of coupled equations for its cumulants. Hence, determining the time-evolution of dark matter density and velocity demands solving the full cumulant hierarchy. While the perfect pressureless fluid model is the only consistent truncation, it cannot describe the dynamics in the multi-streaming regime. Given this inadequacy of truncations for the cumulant hierarchy, I suggest to take a closer look at closure schemes that rely on recurrence. To this end, I will introduce Schrödinger-Poisson as theoretically motivated and phenomenologically viable approximation to Vlasov-Poisson. I will show how Schrödinger-Poisson generates cumulants at all orders consistently and hence can serve as inspirational example for finding closure schemes.
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Vlasov-Poisson in cosmology and plasma physics: monokinetic and multi-beam/stream solutions" (2017)

Germain, Pierre (NYU Courant) WPI, OMP 1, Seminar Room 08.135 Fri, 22. Dec 17, 10:00
Recent mathematical progress on weak turbulence”
I will present two recent rigorous results on weak turbulence: the first one is on the local well-posedness of the kinetic wave equation (with A. Ionescu and M.-B. Tran). And the second one on the derivation of the kinetic wave equation from the nonlinear Schrodinger equation (work in progress, with T. Buckmaster, Z. Hani, and J. Shatah).
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Vlasov-Poisson in cosmology and plasma physics: monokinetic and multi-beam/stream solutions" (2017)

Golse, Francois (CNRS X Palaiseau) WPI, OMP 1, Seminar Room 08.135 Fri, 22. Dec 17, 14:30
From quantum N-body problem to Vlasov via „optimal transport“
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Vlasov-Poisson in cosmology and plasma physics: monokinetic and multi-beam/stream solutions" (2017)

Fritz, Jörg (Saalbau Weltraum Projekt) Maria-Theresien-Platz, 1010 Vienna, Lecture Hall of Natural History Museum Wed, 11. Apr 18, 9:25
Shock metamorphism of meteorites: A record of Impact cratering events in the planetary system
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Observers, modelers, and experimentalists - 3-in-1 to better understand Impact cratering" (2018)

Pittarello, Lidia (U. Wien) Maria-Theresien-Platz, 1010 Vienna, Lecture Hall of Natural History Museum Wed, 11. Apr 18, 9:40
Shock metamorphic effects in a common Mineral: shocked plagioclase in nature and experiments
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Observers, modelers, and experimentalists - 3-in-1 to better understand Impact cratering" (2018)

Deutsch, Alex (U. Münster) Maria-Theresien-Platz, 1010 Vienna, Lecture Hall of Natural History Museum Wed, 11. Apr 18, 9:55
A simple cooking recipe for dating impact events
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Observers, modelers, and experimentalists - 3-in-1 to better understand Impact cratering" (2018)

Goderis, Steven (U. Brussel) Maria-Theresien-Platz, 1010 Vienna, Lecture Hall of Natural History Museum Wed, 11. Apr 18, 10:10
Recent advances in tracing meteoritic contributions to the Earth's crust
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Observers, modelers, and experimentalists - 3-in-1 to better understand Impact cratering" (2018)

Collins, Gareth (Imperial College London) Maria-Theresien-Platz, 1010 Vienna, Lecture Hall of Natural History Museum Wed, 11. Apr 18, 10:55
A brief introduction to numerical Impact modelling
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Observers, modelers, and experimentalists - 3-in-1 to better understand Impact cratering" (2018)

Rae, Auriol (Imperial College London) Maria-Theresien-Platz, 1010 Vienna, Lecture Hall of Natural History Museum Wed, 11. Apr 18, 11:15
Combining observations of shock metamorphism with numerical Impact simulations: Insights into complex crater formation
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Observers, modelers, and experimentalists - 3-in-1 to better understand Impact cratering" (2018)

Alac, Ruken (U. Sydney) Maria-Theresien-Platz, 1010 Vienna, Lecture Hall of Natural History Museum Wed, 11. Apr 18, 11:30
Modeling of Pantasma impact crater using Badlands software with Monte Carlo method
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Observers, modelers, and experimentalists - 3-in-1 to better understand Impact cratering" (2018)

Poelchau, Michael (U. Freiburg) Maria-Theresien-Platz, 1010 Vienna, Lecture Hall of Natural History Museum Wed, 11. Apr 18, 11:45
Shooting into Stone - What we learned from the MEMIN Project
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on "Observers, modelers, and experimentalists - 3-in-1 to better understand Impact cratering" (2018)

David Muraki (Simon Fraser Univ, BC) WPI, OMP 1, Seminar Room 08.135 Mon, 7. May 18, 15:00
Mysterious Holes in the Sky & A Theory for the Motion of Cloud Edges
A holepunch cloud is a curious and rare atmospheric feature where an aircraft, descending or ascending through a thin cloud layer, leaves behind a growing circular hole of clear air. Observed since the early days of aviation, only in 2011 was this holepunch phenomenon simulated in a full-physics numerical weather model. Although the initiation process has long been explained by ice crystal formation, the continued growth of the hole, even up to an hour after its birth, remained a bit of a fluid dynamical mystery. We begin by excluding some of the ``obvious" reasons by tweaking the physics in the numerical simulations (fake weather!). We then attribute the expansion of the hole to the presence of an expanding wavefront. The leading edge of this wave is a front of phase change, where cloudy air is continually evaporated and so expands the hole. Our explanation has led us towards the development of a more general theory for an understanding of how atmospheric waves can evolve the shape of clouds. This work is in collaboration with R Rotunno (NCAR), H Morrison (NCAR), R Walsh (SFU) and H Lynn (SFU).
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)

Mauser, Norbert J. (WPI c/o U.Wien) WPI, OMP 1, Seminar Room 08.135 Tue, 22. May 18, 13:30
TBA
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on “Numerics for cosmology – the Schrodinger method” (2018)

Hahn, Oliver (Observatoire Nice) WPI, OMP 1, Seminar Room 08.135 Tue, 22. May 18, 14:00
TBA
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on “Numerics for cosmology – the Schrodinger method” (2018)

Kopp, Michael WPI, OMP 1, Seminar Room 08.135 Tue, 22. May 18, 14:30
TBA
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on “Numerics for cosmology – the Schrodinger method” (2018)

Athanassoulis, Agis (U. Dundee) WPI, OMP 1, Seminar Room 08.135 Wed, 23. May 18, 10:00
TBA
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on “Numerics for cosmology – the Schrodinger method” (2018)

Gosenca, Mateja (U.Sussex) WPI, OMP 1, Seminar Room 08.135 Wed, 23. May 18, 10:30
TBA
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on “Numerics for cosmology – the Schrodinger method” (2018)

Rampf, Cornelius (U. Heidelberg) WPI, OMP 1, Seminar Room 08.135 Wed, 23. May 18, 15:00
TBA
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on “Numerics for cosmology – the Schrodinger method” (2018)

Uhlemann, Cora (DAMTP Cambridge) WPI, OMP 1, Seminar Room 08.135 Wed, 23. May 18, 16:00
TBA
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on “Numerics for cosmology – the Schrodinger method” (2018)

Zhang, Yong (WPI c/o U. Wien) WPI, OMP 1, Seminar Room 08.135 Thu, 24. May 18, 9:30
TBA
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on “Numerics for cosmology – the Schrodinger method” (2018)

Zhao, Xiaofei (U. Rennes1) WPI, OMP 1, Seminar Room 08.135 Thu, 24. May 18, 10:00
TBA
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on “Numerics for cosmology – the Schrodinger method” (2018)

Skordis, Constantinos (CEICO) WPI, OMP 1, Seminar Room 08.135 Thu, 24. May 18, 14:30
TBA
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on “Numerics for cosmology – the Schrodinger method” (2018)

Katsaounis, Theodoros (U. FORTH c/o KAUST) WPI, OMP 1, Seminar Room 08.135 Fri, 25. May 18, 10:00
TBA
  • Thematic program: Models in Plasmas, Earth and Space Science (2017/2018)
  • Event: Workshop on “Numerics for cosmology – the Schrodinger method” (2018)

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