584 Matching Results

Search Results

Advanced search parameters have been applied.

Center for Momentum Transport and Flow Organization in Plasmas and Magnetofluids (CMTFO)

Description: The CMTFO funding partially supports a junior researcher and a graduate student at UCI. During this project, we have further developed the global gyrokinetic particle code GTC to study the momentum transport in tokamak driven by electrostatic ion temperature gradient (ITG) turbulence [1] with kinetic electrons and by collisionless trapped electron mode (CTEM) turbulence [2]. We have also upgraded GTC for fully electromagnetic simulation and for linear plasma configuration with verification and validation of the electron temperature gradient (ETG) turbulence in Columbia Linear Machine. The followings are the highlights on the physics results reported in the key publications of this project.
Date: February 28, 2014
Creator: Lin, Zhihong
Partner: UNT Libraries Government Documents Department

SciDAC Center for Gyrokinetic Particle Simulation of Turbulent Transport in Burning Plasmas

Description: During the first year of the SciDAC gyrokinetic particle simulation (GPS) project, the GPS team (Zhihong Lin, Liu Chen, Yasutaro Nishimura, and Igor Holod) at the University of California, Irvine (UCI) studied the tokamak electron transport driven by electron temperature gradient (ETG) turbulence, and by trapped electron mode (TEM) turbulence and ion temperature gradient (ITG) turbulence with kinetic electron effects, extended our studies of ITG turbulence spreading to core-edge coupling. We have developed and optimized an elliptic solver using finite element method (FEM), which enables the implementation of advanced kinetic electron models (split-weight scheme and hybrid model) in the SciDAC GPS production code GTC. The GTC code has been ported and optimized on both scalar and vector parallel computer architectures, and is being transformed into objected-oriented style to facilitate collaborative code development. During this period, the UCI team members presented 11 invited talks at major national and international conferences, published 22 papers in peer-reviewed journals and 10 papers in conference proceedings. The UCI hosted the annual SciDAC Workshop on Plasma Turbulence sponsored by the GPS Center, 2005-2007. The workshop was attended by about fifties US and foreign researchers and financially sponsored several gradual students from MIT, Princeton University, Germany, Switzerland, and Finland. A new SciDAC postdoc, Igor Holod, has arrived at UCI to initiate global particle simulation of magnetohydrodynamics turbulence driven by energetic particle modes. The PI, Z. Lin, has been promoted to the Associate Professor with tenure at UCI.
Date: December 18, 2013
Creator: Lin, Zhihong
Partner: UNT Libraries Government Documents Department

Final Technical Report: Global Field Aligned Mesh and Gyrokinetic Field Solver in a Tokamak Edge Geometry

Description: This project was a collaboration between researchers at the California Institute of Technology and the University of California, Irvine to investigate the utility of a global field-aligned mesh and gyrokinetic field solver for simulations of the tokamak plasma edge region. Mesh generation software from UC Irvine was tested with specific tokamak edge magnetic geometry scenarios and the quality of the meshes and the solutions to the gyrokinetic Poisson equation were evaluated.
Date: May 15, 2013
Creator: Cummings, Julian C.
Partner: UNT Libraries Government Documents Department

Implementations of mesh refinement schemes for particle-in-cell plasma simulations

Description: Plasma simulations are often rendered challenging by the disparity of scales in time and in space which must be resolved. When these disparities are in distinctive zones of the simulation region, a method which has proven to be effective in other areas (e.g. fluid dynamics simulations) is the mesh refinement technique. We briefly discuss the challenges posed by coupling this technique with plasma Particle-In-Cell simulations and present two implementations in more detail, with examples.
Date: October 20, 2003
Creator: Vay, J.-L.; Colella, P.; Friedman, A.; Grote, D.P.; McCorquodale, P. & Serafini, D.B.
Partner: UNT Libraries Government Documents Department

Novel Methods in the Particle-In-Cell Accelerator Code-Framework Warp

Description: The Particle-In-Cell (PIC) Code-Framework Warp is being developed by the Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL) to guide the development of accelerators that can deliver beams suitable for high energy density experiments and implosion of inertial fusion capsules. It is also applied in various areas outside the Heavy Ion Fusion program to the study and design of existing and next-generation high-energy accelerators, including the study of electron cloud effects and laser wakefield acceleration for example. This paper presents an overview of Warp’s capabilities, summarizing recent original numerical methods that were developed by the HIFS-VNL (including Particle-In-Cell with Adaptive Mesh Refinement, a large-timestep “drift-Lorentz” mover for arbitrarily magnetized species, a relativistic Lorentz invariant leapfrog particle pusher, simulations in Lorentz boosted frames, an electromagnetic solver with tunable numerical dispersion and efficient stride20 based digital filtering), with great emphasis on the description of the mesh refinement capability. Selected examples of applications of the methods to the abovementioned fields are given.
Date: September 1, 2011
Creator: Vay, J.-L.; Grote, D. P.; Cohen, R. H.; Friedman, A.; Grote, D. P.; Cohen, R. H. et al.
Partner: UNT Libraries Government Documents Department

Dynamics of a plasma discharge in a mirror field

Description: A cool plasma discharge in mirror geometry is modeled with ions flowing along field lines into electrodes beyond the throats. The velocity of the flow is determined by the electrode sheath prcpenties and nozzle-like phenomena in the mirror and ion source. This model is applicable to the wet-wood burner'' reactor and mirror target schemes. (auth)
Date: January 24, 1974
Creator: Lee, E. P. & McNamara, B.
Partner: UNT Libraries Government Documents Department

Numerical simulations of plasmas with smoothing in phase space and filtering in time. Progress report, October 1, 1972--September 30, 1973

Description: The research is directed tcward the development of new numerical methods for plasma simulation and their application to physical problems of current interest to Controlled Thermonuclear Research. During the past year, research on the project has been concerned with the following problems- (1) analysis of numerical effects in particle simulation of whistler wave propagation, (2) theoretical and numerical studies of triggered emissions from electrons correlated in phase by a large-amplitude whistler wave, (3) development of long- time-step algorithms, and (4) anomalous absorption of radiation in weakly' collisional plasmas. (auth)
Date: January 1, 1973
Creator: Denavit, J.
Partner: UNT Libraries Government Documents Department

Final Technical Report

Description: This is the final report for the Research Grant DE-FG02-08ER54989 'Edge Plasma Simulations in NSTX and CTF: Synergy of Lithium Coating, Non-Diffusive Anomalous Transport and Drifts'. The UCSD group including: A.Yu. Pigarov (PI), S.I. Krasheninnikov and R.D. Smirnov, was working on modeling of the impact of lithium coatings on edge plasma parameters in NSTX with the multi-species multi-fluid code UEDGE. The work was conducted in the following main areas: (i) improvements of UEDGE model for plasma-lithium interactions, (ii) understanding the physics of low-recycling divertor regime in NSTX caused by lithium pumping, (iii) study of synergistic effects with lithium coatings and non-diffusive ballooning-like cross-field transport, (iv) simulation of experimental multi-diagnostic data on edge plasma with lithium pumping in NSTX via self-consistent modeling of D-Li-C plasma with UEDGE, and (v) working-gas balance analysis. The accomplishments in these areas are given in the corresponding subsections in Section 2. Publications and presentations made under the Grant are listed in Section 3.
Date: June 5, 2012
Creator: Pigarov, Alexander
Partner: UNT Libraries Government Documents Department

Collaborative Research: Dynamics of Electrostatic Solitary Waves and their Effects on Current Layers

Description: The contents of this final report require explanation, as the report cannot be written in a manner consistent with the usual guidelines for a final scientific technical report. The original PI on this grant was Professor Paul Kintner who passed away November 16, 2010. I, Charles E. Seyler, was asked by the Director of the School of Electrical and Computer Engineering to take over the grant last May and try to fulfill its obligations to the PIs at the lead institution (UNH). I have worked with Professor Kintner over the years and have published joint papers with him on the subject of this grant. Consequently, I was in the best position to carry out the remainder of the grant obligations at Cornell. When the grant was transferred to me, I immediately contacted the PI, Li-Jen Chen, and asked about the obligations of the Cornell collaboration and what plans Professor Kintner had made had done previously to meet them. I also offered my assistance in the way of contributing to the project in a way that my background would allow. I have considerable experience in interpretation of space-related data and I am somewhat familiar with LAPD. I have also performed plasma simulations related to electrostatic solitary waves, which is more directly related to my expertise. Dr. Chen's response was: 'Paul's role is to participate in the solitary wave experiments that we do at LAPD, and offer his experimentalist expertise during the experiments and related discussions. There is still the third experiment in a series of three to be carried out. The date is not set yet.' I later indicated that I could devote about two weeks of summer research to the project and asked the UNH group if there was anything that they would like me to do in the way ...
Date: October 17, 2007
Creator: Kintner, Paul M.
Partner: UNT Libraries Government Documents Department

Application of adaptive mesh refinement to particle-in-cell simulations of plasmas and beams

Description: Plasma simulations are often rendered challenging by the disparity of scales in time and in space which must be resolved. When these disparities are in distinctive zones of the simulation domain, a method which has proven to be effective in other areas (e.g. fluid dynamics simulations) is the mesh refinement technique. We briefly discuss the challenges posed by coupling this technique with plasma Particle-In-Cell simulations, and present examples of application in Heavy Ion Fusion and related fields which illustrate the effectiveness of the approach. We also report on the status of a collaboration under way at Lawrence Berkeley National Laboratory between the Applied Numerical Algorithms Group (ANAG) and the Heavy Ion Fusion group to upgrade ANAG's mesh refinement library Chombo to include the tools needed by Particle-In-Cell simulation codes.
Date: November 4, 2003
Creator: Vay, J.-L.; Colella, P.; Kwan, J.W.; McCorquodale, P.; Serafini, D.B.; Friedman, A. et al.
Partner: UNT Libraries Government Documents Department

Portable implementation of implicit methods for the UEDGE and BOUT codes on parallel computers

Description: A description is given of the parallelization algorithms and results for two codes used ex- tensively to model edge-plasmas in magnetic fusion energy devices. The codes are UEDGE, which calculates two-dimensional plasma and neutral gas profiles, and BOUT, which cal- culates three-dimensional plasma turbulence using experimental or UEDGE profiles. Both codes describe the plasma behavior using fluid equations. A domain decomposition model is used for parallelization by dividing the global spatial simulation region into a set of domains. This approach allows the used of two recently developed LLNL Newton-Krylov numerical solvers, PVODE and KINSOL. Results show an order of magnitude speed up in execution time for the plasma equations with UEDGE. A problem which is identified for UEDGE is the solution of the fluid gas equations on a highly anisotropic mesh. The speed up of BOUT is closer to two orders of magnitude, especially if one includes the initial improvement from switching to the fully implicit Newton-Krylov solver. The turbulent transport coefficients obtained from BOUT guide the use of anomalous transport models within UEDGE, with the eventual goal of a self-consistent coupling.
Date: February 17, 1999
Creator: Rognlien, T D & Xu, X Q
Partner: UNT Libraries Government Documents Department

Recent progress in linear and nonlinear studies of toroidal Alfven eigenmode

Description: TAE modes are studied in linear and nonlinear regimes using several kinetic/MHD hybrid models. It is shown that the stability of TAE mode is largely determined by its radial mode structure. The calculated stability thresholds are correlated well with observations, including the recently observed alpha-driven TAE modes in the TFTR DT experiments. In the nonlinear regime, quasilinear simulations with multiple modes show that the saturation level is enhanced by nonlinear wave-particle resonance overlapping when the linear growth rate exceeds a critical value. A fully self-consistent {delta}f noise reduction method for the 3D particle/MHD hybrid model is developed.
Date: May 1, 1997
Creator: Fu, G.Y.; Chen, Y. & Budny, R.
Partner: UNT Libraries Government Documents Department

Collisionless damping of perpendicular magnetosonic waves in a two-ion-species plasma

Description: Propagation of finite-amplitude magnetosonic waves in a collisionless plasma containing two ion species is studied with a one-dimensional, fully electromagnetic code based on a three-fluid model. It is found that perpendicular magnetosonic waves are damped in a two-ion-species plasma; a magnetosonic pulse accelerates heavy ions in the direction parallel to the wave front, which results in the excitation of a longer wavelength perturbation behind the pulse. The damping due to the energy transfer from the original pulse to the longer wavelength perturbation occurs even if the plasma is collisionless and the pulse amplitude is small. The theoretically obtained damping rate is in agreement with the simulation result.
Date: August 1, 1996
Creator: Dogen, Daiju; Toida, Mieko & Ohsawa, Yukiharu
Partner: UNT Libraries Government Documents Department