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in creator/contributor: "Parker, S. E."  
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Numerical error in electron orbits with large. omega. sub ce. delta. t

Description: We have found that running electrostatic particle codes relatively large {omega}{sub ce}{Delta}t in some circumstances does not significantly affect the physical results. We first present results from a single particle mover finding the correct first order drifts for large {omega}{sub ce}{Delta}t. We then characterize the numerical orbit of the Boris algorithm for rotation when {omega}{sub ce}{Delta}t {much gt} 1. Next, an analysis of the guiding center motion is given showing why the first ord… more
Date: December 20, 1989
Creator: Parker, S. E. & Birdsall, C. K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A fully nonlinear characteristic method for gyrokinetic simulation

Description: We present a new scheme which evolves the perturbed part of the distribution function along a set of characteristics that solves the fully nonlinear gyrokinetic equations. This nonlinear characteristic method for particle simulation is an extension of the partially linear weighting scheme, and may be considered an improvement of existing {delta} f methods. Some of the features of this new method are: the ability to keep all of the nonlinearities, particularly those associated with parallel acce… more
Date: July 1, 1992
Creator: Parker, S. E. & Lee, W. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A fully nonlinear characteristic method for gyrokinetic simulation

Description: We present a new scheme which evolves the perturbed part of the distribution function along a set of characteristics that solves the fully nonlinear gyrokinetic equations. This nonlinear characteristic method for particle simulation is an extension of the partially linear weighting scheme, and may be considered an improvement of existing {delta} f methods. Some of the features of this new method are: the ability to keep all of the nonlinearities, particularly those associated with parallel acce… more
Date: July 1, 1992
Creator: Parker, S. E. & Lee, W. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Transport in gyrokinetic tokamaks

Description: A comprehensive study of transport in full-volume gyrokinetic (gk) simulations of ion temperature gradient driven turbulence in core tokamak plasmas is presented. Though this ``gyrokinetic tokamak`` is much simpler than experimental tokamaks, such simplicity is an asset, because a dependable nonlinear transport theory for such systems should be more attainable. Toward this end, we pursue two related lines of inquiry. (1) We study the scalings of gk tokamaks with respect to important system para… more
Date: January 1, 1995
Creator: Mynick, H. E. & Parker, S. E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A particle-in-cell method for modeling small angle Coulomb collisions in plasmas

Description: We propose a computational method to self-consistently model small angle collisional effects. This method may be added to standard Particle-In-Cell (PIC) plasma simulations to include collisions, or as an alternative to solving the Fokker-Planck (FP) equation using finite difference methods. The distribution function is represented by a large number of particles. The particle velocities change due to the drag force, and the diffusion in velocity is represented by a random process. This is simil… more
Date: January 1, 1989
Creator: Parker, S. E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Gyrokinetic simulation of ion temperature gradient driven turbulence in 3D toroidal geometry

Description: Results from a fully nonlinear three dimensional toroidal electrostatic gyrokinetic simulation of the ion temperature gradient instability are presented. The model has fully gyro-averaged ion dynamics, including trapped particles, and adiabatic electrons. Simulations of large tokamak plasma volumes are made possible due to recent advances in {delta}f methods and massively parallel computing. Linearly, a coherent ballooning eigenmode is observed, where the mode is radially elongated. In the turb… more
Date: May 1, 1993
Creator: Parker, S. E.; Lee, W. W. & Santoro, R. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Gyrokinetic simulation of ion temperature gradient driven turbulence in 3D toroidal geometry

Description: Results from a fully nonlinear three dimensional toroidal electrostatic gyrokinetic simulation of the ion temperature gradient instability are presented. The model has fully gyro-averaged ion dynamics, including trapped particles, and adiabatic electrons. Simulations of large tokamak plasma volumes are made possible due to recent advances in [delta]f methods and massively parallel computing. Linearly, a coherent ballooning eigenmode is observed, where the mode is radially elongated. In the turb… more
Date: May 1, 1993
Creator: Parker, S. E.; Lee, W. W. & Santoro, R. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Renormalized dissipation in plasmas with finite collisionality

Description: A nonlinear truncation procedure for Fourier-Hermite expansion of Boltzmann-type plasma equations is presented which eliminates fine velocity scale, taking into account its effect on coarser scales. The truncated system is then transformed back to (x, v) space which results in a renormalized Boltzmann equation. The resulting equation may allow for coarser velocity space resolution in kinetic simulations while reducing to the original Boltzmann equation when fine velocity scales are resolved. To… more
Date: May 1, 1995
Creator: Parker, S. E. & Carati, D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Multi-scale particle simulation of bounded plasmas

Description: We are using the multi-scale technique to model bounded systems. Certain bounded systems are a naturally suited for the multi-scale method because of the boundary layer that forms at the wall, which is usually a short spatial and time scale structure, can significantly affect the bulk plasma behavior. One goal is to understand the interaction between the bulk plasma and the sheath. If the relevant short time scale physics is local to a few known spatial regions, then one can take advantage of t… more
Date: January 1, 1989
Creator: Parker, S. E.; Birdsall, C. K.; Friedman, A. & Ray, S. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Verification of Gyrokinetic (delta)f Simulations of Electron Temperature Gradient Turbulence

Description: The GEM gyrokinetic {delta}f simulation code [Chen, 2003] [Chen, 2007] is shown to reproduce electron temperature gradient turbulence at the benchmark operating point established in previous work [Nevins, 2006]. The electron thermal transport is within 10% of the expected value, while the turbulent fluctuation spectrum is shown to have the expected intensity and two-point correlation function.
Date: May 7, 2007
Creator: Nevins, W. M.; Parker, S. E.; Chen, Y.; Candy, J.; Dimits, A.; Dorland, W. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Comparisons of gyrofluid and gyrokinetic simulations

Description: The gyrokinetic and gyrofluid models show the most promise for large scale simulations of tokamak microturbulence. This paper discusses detailed comparisons of these two complementary approaches. Past comparisons with linear theory have been fairly good, therefore the emphasis here is on nonlinear comparisons. Simulations include simple two dimensional slab test cases, turbulent three dimensional slab cases, and toroidal cases, each modeling the nonlinear evolution of the ion temperature gradie… more
Date: March 1, 1994
Creator: Parker, S. E.; Dorland, W.; Santoro, R. A.; Beer, M. A.; Liu, Q. P.; Lee, W. W. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Simulation of ion-temperature-gradient turbulence in tokamaks

Description: Results are presented from nonlinear gyrokinetic simulations of toroidal ion temperature gradient (ITG) turbulence and transport. The gyrokinetic simulations are found to yield values of the thermal diffusivity significantly lower than gyrofluid or IFS-PPPL-model predictions. A new phenomenon of nonlinear effective critical gradients larger than the linear instability threshold gradients is observed, and is associated with undamped flux-surface-averaged shear flows. The nonlinear gyrokineic cod… more
Date: October 14, 1998
Creator: Cohen, B I; Dimits, A M; Kim, C; Mattor, N; Nevins, W M; Parker, S E et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Kinetic studies of microinstabilities in toroidal plasmas: Simulation and theory

Description: A comprehensive program for the development and use of particle simulation techniques for solving the gyrokinetic Vlasov-Maxwell equations on massively parallel computers has been carried out at Princeton Plasma Physics Laboratory. This is a key element of our ongoing theoretical efforts to systematically investigate physics issues vital to understanding tokamak plasmas. In this paper, our focus is on spatial-gradient-driven microinstabilities. Their importance is supported by the recent progre… more
Date: December 1, 1992
Creator: Lee, W. W.; Haham, T. S.; Parker, S. E.; Perkins, F. W.; Rath, S.; Rewoldt, G. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Kinetic Studies of Microinstabilities in Toroidal Plasmas: Simulation and Theory

Description: A comprehensive program for the development and use of particle simulation techniques for solving the gyrokinetic Vlasov-Maxwell equations on massively parallel computers has been carried out at Princeton Plasma Physics Laboratory. This is a key element of our ongoing theoretical efforts to systematically investigate physics issues vital to understanding tokamak plasmas. In this paper, our focus is on spatial-gradient-driven microinstabilities. Their importance is supported by the recent progre… more
Date: December 1992
Creator: Lee, W. W.; Haham, T. S.; Parker, S. E.; Perkins, F. W.; Rath, S.; Rewoldt, G. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Analytical solutions and particle simulations of cross-field plasma sheaths

Description: Particles simulations have been made of an infinite plasma slab, bounded by absorbing conducting walls, with a magnetic field parallel to the walls. The simulations have been either 1-D, or 2-D, with the magnetic field normal to the simulation plane. Initially, the plasma has a uniform density between the walls, and there is a uniform source of ions and electrons to replace particles lost to the walls. In the 1-D case, there is no diffusion of the particle guiding centers, and the plasma remain… more
Date: August 30, 1989
Creator: Gerver, M. J. (Massachusetts Inst. of Tech., Cambridge, MA (USA). Plasma Fusion Center); Parker, S. E. & Theilhaber, K. (California Univ., Berkeley, CA (USA). Electronics Research Lab.)
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Numerical Tokamak Turbulence Project

Description: The primary research objective of the Numerical Tokamak Turbulence Project (NTTP) is to develop a predictive ability in modeling turbulent transport due to drift-type instabilities in the core of tokamak fusion experiments, through the use of three-dimensional kinetic and fluid simulations and the derivation of reduced models.
Date: December 9, 1999
Creator: Cohen, B.; Dawson, J. M.; Reynders, J. V. W.; Decyk, V. K.; Dorland, W. D.; Hammett, G. W. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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