Practical Gyrokinetics

Catto, Peter J.

doi:10.7910/DVN/KXUFAN

Title: Practical Gyrokinetics

Dataset
Other Related Research

Abstract

Thousands of gyrokinetic papers have been published since the introduction of the gyrokinetic change of variables. The intent here is not to review the field, but rather the goal is to present a tutorial providing insight into why gyrokinetics is an appropriate description of turbulent transport. The focus is on turbulent transport in axisymmetric tokamaks, but many of the ideas and techniques are applicable to stellarators and other magnetic fusion devices with nested surfaces of constant pressure. Besides the origins of gyrokinetics and recent insights, gyrokinetic orderings and gyrokinetic variables are summarized. Then a compact, but careful, derivation of the simplest electrostatic gyrokinetic equation for tokamaks is presented, along with a brief mention of gyrokinetics for stellarators. The advantages of assuming scale separation between the finer scales and faster time variation of the turbulence and the global behavior and slow temporal evolution of the background are stressed. Moreover, the procedure for removing the adiabatic or Maxwell-Boltzmann response is emphasized. Scale separation allows the near Maxwellian behavior of the background and the rapid variation of the turbulence to be described by separate local gyrokinetic equations. The turbulent fluctuations are found by solving the nonlinear gyrokinetic equation for the non-adiabatic portion ofmore »« less

Authors:

Catto, Peter J.

OSTI

Publication Date:: Thu Dec 20 04:00:00 UTC 2018

DOE Contract Number:: FG02-91ER54109

Research Org.:: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center

Sponsoring Org.:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Subject:: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY

OSTI Identifier:: 1880544

DOI:: https://doi.org/10.7910/DVN/KXUFAN

Citation Formats


                    Catto, Peter J. Practical Gyrokinetics.  United States: N. p., 2018. 
        Web.  doi:10.7910/DVN/KXUFAN.

Copy to clipboard


                    Catto, Peter J. Practical Gyrokinetics.  United States.  doi:https://doi.org/10.7910/DVN/KXUFAN

Copy to clipboard


                    Catto, Peter J. 2018.  
"Practical Gyrokinetics".  United States.  doi:https://doi.org/10.7910/DVN/KXUFAN.  https://www.osti.gov/servlets/purl/1880544. Pub date:Thu Dec 20 04:00:00 UTC 2018

Copy to clipboard


                    
@article{osti_1880544,

  title        = {Practical Gyrokinetics},

  author       = {Catto, Peter J.},

  abstractNote = {Thousands of gyrokinetic papers have been published since the introduction of the gyrokinetic change of variables. The intent here is not to review the field, but rather the goal is to present a tutorial providing insight into why gyrokinetics is an appropriate description of turbulent transport. The focus is on turbulent transport in axisymmetric tokamaks, but many of the ideas and techniques are applicable to stellarators and other magnetic fusion devices with nested surfaces of constant pressure. Besides the origins of gyrokinetics and recent insights, gyrokinetic orderings and gyrokinetic variables are summarized. Then a compact, but careful, derivation of the simplest electrostatic gyrokinetic equation for tokamaks is presented, along with a brief mention of gyrokinetics for stellarators. The advantages of assuming scale separation between the finer scales and faster time variation of the turbulence and the global behavior and slow temporal evolution of the background are stressed. Moreover, the procedure for removing the adiabatic or Maxwell-Boltzmann response is emphasized. Scale separation allows the near Maxwellian behavior of the background and the rapid variation of the turbulence to be described by separate local gyrokinetic equations. The turbulent fluctuations are found by solving the nonlinear gyrokinetic equation for the non-adiabatic portion of the fluctuating distribution function. Also, generalizations of the gyrokinetic equation so that it retains electromagnetic and flow modifications are considered in detail along with some symmetry properties. In addition, ambipolarity, particle transport, and heat transport are addressed, along with a discussion of the complications associated with describing momentum transport and profile evolution.},

  doi          = {10.7910/DVN/KXUFAN},

  journal      = {},

  number       = ,

  volume       = ,

  place        = {United States},

  year         = {Thu Dec 20 04:00:00 UTC 2018},

  month        = {Thu Dec 20 04:00:00 UTC 2018}

}

Copy to clipboard

Dataset:

View Dataset

DOI: https://doi.org/10.7910/DVN/KXUFAN

Save / Share:

Export Metadata

Save to My Library

Similar records in DOE Data Explorer and OSTI.GOV collections:

Symmetries of a reduced fluid-gyrokinetic system

Dataset White, R. L. ; Hazeltine, R. D. ; Loureiro, N. F.

Symmetries of a fluid-gyrokinetic model are investigated using Lie group techniques. Specifically the nonlinear system constructed by Zocco and Schekochihin (Zocco & Schekochihin 2011), which combines nonlinear fluid equations with a drift-kinetic description of parallel electron dynamics, is studied. Significantly, this model is fully gyrokinetic, allowing for arbitrarymore »« less
Gyrokinetic Landau collision operator in conservative form

Dataset Pan, Qingjiang ; Ernst, Darin R.

A gyrokinetic linearized exact (not model) Landau collision operator is derived by transforming the symmetric and conservative Landau form. The formulation obtains the velocity-space flux density and preserves the operator’s conservative form as the divergence of this flux density. The operator contains both test-particle and field-particle contributions, and finite Larmor radius effects are evaluated in either Bessel function series or gyrophase integrals. While equivalent to the gyrokinetic Fokker–Planck form with Rosenbluth potentials [B. Li and D. R. Ernst, Phys. Rev. Lett. 106, 195002 (2011)], the gyrokinetic conservative Landau form explicitly preserves the symmetry between test-particle and field-particle contributions, which underliesmore »« less
Turbulent field fluctuations in gyrokinetic and fluid plasmas

Dataset Mathews, Abhilash ; Mandell, Noah ; Francisquez, Manaure ; ...

A key uncertainty in the design and development of magnetic confinement fusion energy reactors is predicting edge plasma turbulence. An essential step in overcoming this uncertainty is the validation in accuracy of reduced turbulent transport models. Drift-reduced Braginskii two-fluid theory is one such set of reduced equations that has for decades simulated boundary plasmas in experiment, but significant questions exist regarding its predictive ability. To this end, using a novel physics-informed deep learning framework, we demonstrate the first ever direct quantitative comparisons of turbulent field fluctuations between electrostatic two-fluid theory and electromagnetic gyrokinetic modelling with good overall agreement found inmore »« less
Quasi-linear gyrokinetic predictions of the Coriolis momentum pinch in NSTX

Dataset Guttenfelder, W. ; Kaye, S. M. ; Ren, Y. ; ...

This paper presents quasi-linear gyrokinetic predictions of the Coriolis momentum pinch for low aspect-ratio NSTX H-modes where previous experimental measurements were focused. Local, linear calculations predict that in the region of interest (just outside the mid-radius) of these relatively high-beta plasmas, profiles are most unstable to microtearing modes that are only effective in transporting electron energy. However, sub-dominant electromagnetic and electrostatic ballooning modes are also unstable, which are effective at transporting energy, particles and momentum. The quasi-linear prediction of transport from these weaker ballooning modes, assuming they contribute transport in addition to that from microtearing modes in a nonlinear turbulentmore »« less
Gyrokinetic simulations of momentum flux parasitic to free-energy transfer

Dataset Stoltzfus-Dueck, T ; Hornsby, W A ; Grosshauser, S R

Ion Landau damping interacts with a portion of the E×B drift to cause a non-diffusive outward flux of co-current toroidal angular momentum. Quantitative evaluation of this momentum flux requires nonlinear simulations to determine fL, the fraction of fluctuation free energy that passes through ion Landau damping, in fully developed turbulence. Nonlinear gyrokinetic simulations with the GKW code confirm the presence of the systematic symmetry-breaking momentum flux. For simulations with adiabatic electrons, fL scales inversely with the ion temperature gradient, because only the ion curvature drift can transfer free energy to the electrostatic potential. Although kinetic electrons should in principle relaxmore »« less

Similar Records