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Linear Analysis and Verification Suite for Edge Turbulence

Description: The edge and scrape-off-layer region of a tokamak plasma is subject to well known resistive and ideal instabilities that are driven by various curvature- and sheath-related mechanisms. While the boundary plasma is typically strongly turbulent in experiments, it is useful to have computational tools that can analyze the linear eigenmode structure, predict quantitative trends in growth rates and elucidate and the underlying drive mechanisms. Furthermore, measurement of the linear growth rate of u… more
Date: April 24, 2008
Creator: Myra, J. R. & Umansky, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Numerical Computation of Wave-Plasma Interactions in Multi-Dimensional Systems

Description: This project studied two kinds of nonlinear interactions between ion cyclotron range of frequency waves and fusion plasmas. A wavelet technique was also developed for analyzing the complex wave fields produced by wave propagation codes.
Date: February 22, 2005
Creator: D'Ippolito, D. A. & Myra, J. R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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ICRF heating and current drive in TFTR supershot plasmas: Data analysis and interpretation of ICRF/edge interactions. Research Progress report

Description: The relevance of rf-sheath-plasma interactions to ICRF operation in TFTR has been studied. Screen-screen and screen-limiter rf sheaths have been identified and analyzed for the old and new Bay M geometries on TFIR, including sheath voltages driven by both feeders and the central antenna conductor. Calculations have been carried out to determine the effects of ICRF on edge transport (profile flattening by E {times} B convection), impurity influx ({delta}Z{sub eff}) and edge electron heating (FS … more
Date: September 22, 1993
Creator: Aamodt, R. E.; D`Ippolito, D. A. & Myra, J. R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Fundamental studies of fusion plasmas

Description: The major portion of this program is devoted to critical ICH phenomena. The topics include edge physics, fast wave propagation, ICH induced high frequency instabilities, and a preliminary antenna design for Ignitor. This research was strongly coordinated with the world's experimental and design teams at JET, Culham, ORNL, and Ignitor. The results have been widely publicized at both general scientific meetings and topical workshops including the speciality workshop on ICRF design and physics spo… more
Date: May 26, 1992
Creator: Aamodt, R. E.; Catto, P. J.; D'Ippolito, D. A.; Myra, J. R. & Russell, D. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Fundamental studies of fusion plasmas

Description: Work on ICRF interaction with the edge plasma is reported. ICRF generated convective cells have been established as an important mechanism for influencing edge transport and interaction with the H-mode, and for controlling profiles in the tokamak scrape-off-layer. Power dissipation by rf sheaths has been shown to be significant for some misaligned ICRF and IIBW antenna systems. Near-field antenna sheath work has been extended to the far-field case, important for experiments with low single pass… more
Date: April 27, 1993
Creator: Aamodt, R. E.; Catto, P. J.; D'Ippolito, D. A.; Myra, J. R. & Russell, D. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Fundamental studies of fusion plasmas. Annual performance report

Description: Work on ICRF interaction with the edge plasma is reported. ICRF generated convective cells have been established as an important mechanism for influencing edge transport and interaction with the H-mode, and for controlling profiles in the tokamak scrape-off-layer. Power dissipation by rf sheaths has been shown to be significant for some misaligned ICRF and IIBW antenna systems. Near-field antenna sheath work has been extended to the far-field case, important for experiments with low single pass… more
Date: April 27, 1993
Creator: Aamodt, R. E.; Catto, P. J.; D`Ippolito, D. A.; Myra, J. R. & Russell, D. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Fundamental studies of fusion plasmas. Annual performance report

Description: The major portion of this program is devoted to critical ICH phenomena. The topics include edge physics, fast wave propagation, ICH induced high frequency instabilities, and a preliminary antenna design for Ignitor. This research was strongly coordinated with the world`s experimental and design teams at JET, Culham, ORNL, and Ignitor. The results have been widely publicized at both general scientific meetings and topical workshops including the speciality workshop on ICRF design and physics spo… more
Date: May 26, 1992
Creator: Aamodt, R. E.; Catto, P. J.; D`Ippolito, D. A.; Myra, J. R. & Russell, D. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Three-Dimensional Neutral Transport Simulations of Gas Puff Imaging Experiments

Description: Gas Puff Imaging (GPI) experiments are designed to isolate the structure of plasma turbulence in the plane perpendicular to the magnetic field. Three-dimensional aspects of this diagnostic technique as used on the National Spherical Torus eXperiment (NSTX) are examined via Monte Carlo neutral transport simulations. The radial width of the simulated GPI images are in rough agreement with observations. However, the simulated emission clouds are angled approximately 15 degrees with respect to the … more
Date: September 19, 2003
Creator: Stotler, D. P.; DIppolito, D. A.; LeBlanc, B.; Maqueda, R. J.; Myra, J. R.; Sabbagh, S. A. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Edge Zonal Flows and Blob Propagation in Alcator C-Mod

Description: Here we describe recent measurements of the 2-D motion of turbulence in the edge and scrape-off layer (SOL) of the Alcator C-Mod tokamak. This data was taken using the outer midplane gas puff imaging (GPI) camera, which views a 6 cm radial by 6 cm poloidal region near the separatrix just below the outer midplane [1]. The data were taken in Ohmic or RF heated L-mode plasmas at 400,000 frames/sec for {approx}50 msec/shot using a Phantom 710 camera in a 64 x 64 pixel format. The resulting 2-D vs. … more
Date: July 25, 2011
Creator: Zweben, S; Agostini, M; Davis, B; Grulke, O; Hager, R; Hughes, J et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Convective Transport in Tokamaks

Description: Scrape-off-layer (SOL) convection in fusion experiments appears to be a universal phenomenon that can ''short-circuit'' the divertor in some cases. The theory of ''blob'' transport provides a simple and robust physical paradigm for studying convective transport. This paper summarizes recent advances in the theory of blob transport and its comparison with 2D and 3D computer simulations. We also discuss the common physical basis relating radial transport of blobs, pellets, and ELMs and a new blob… more
Date: February 16, 2005
Creator: D'Ippolito, D. A.; Myra, J. R.; Russell, D. A.; Krasheninnikov, S. I.; Pigarov, A. Y.; Yu, G. Q. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Turbulence simulations of x-point physics on the L-H transitions

Description: We show that the resistive X-point mode is dominant mode in boundary plasmas in X-point divertor geometry. The poloidal fluctuation phase velocity from the resistive X-point turbulence shows experimentally measured structure across separatrix. The fluctuation phase velocity is larger than E x B velocity both in L and H mode phases, by at least a factor of two. We also demonstrate that there is a strong poloidal asymmetry of particle flux in the proximity of the separatrix. Turbulence suppressio… more
Date: September 28, 2000
Creator: Xu, X. Q.; Cohen, R. H.; Nevins, W. M.; Porter, G. D.; Rensink, M. E.; Rognlien, T. D. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Comparison of Edge Turbulence Imaging at Two Different Poloidal Locations in the Scrape-off Layer of Alcator C-Mod

Description: This paper describes 2-D imaging measurements of plasma turbulence made in the scrape-off layer of the Alcator C-Mod tokamak simultaneously at two different poloidal locations, one near the outer midplane and the other near the divertor X-point region. These images were made with radial and poloidal resolution using two gas puff imaging (GPI) diagnostics, which were not directly connected along a B field line. The turbulence correlation structure has a significantly different tilt angle with re… more
Date: March 29, 2013
Creator: Zweben, S. J.; Terry, J. L.; Agostini, M.; Davis, W. M.; Diallo, A.; Ellis, R. A. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Density Effects on Tokamak Edge Turbulence and Transport with Magnetic X-points

Description: Results are presented from the 3D electromagnetic turbulence code BOUT, the 2D transport code UEDGE, and theoretical analysis of boundary turbulence and transport in a real divertor-plasma geometry and its relationship to the density limit. Key results include: (1) a transition of the boundary turbulence from resistive X-point to resistive-ballooning as a critical plasma density is exceeded; (2) formation of an X-point MARFE in 2D UEDGE transport simulations for increasing outboard radial trans… more
Date: October 12, 2004
Creator: Xu, X. Q.; Cohen, R. H.; Nevins, W. M.; Rognlien, T. D.; Ryutov, D. D.; Umansky, M. V. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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