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Simulation Of Edge Plasmas In Diii D Double Null Configurations
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Book Synopsis Simulation of Edge Plasmas in DIII-D Double-Null Configurations by :
Download or read book Simulation of Edge Plasmas in DIII-D Double-Null Configurations written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present fluid model simulation results for the edge plasma in the DIII-D tokamak with unbalanced double-null magnetic configurations, including cross field drifts. Input parameters are typical of low-power operation in DIII-D. For high-recycling the plasma tends to be detached from all divertor plates. Midplane plasma and electric field profiles are relatively insensitive to the magnetic imbalance. Divertor heat flux profiles exhibit sharp peaks due to cross-field drifts when the ion grad-B drift direction is away from the x-point toward the magnetic axis.
Book Synopsis UEDGE Simulation of Edge Plasmas in DIII-D Double Null Configurations by :
Download or read book UEDGE Simulation of Edge Plasmas in DIII-D Double Null Configurations written by and published by . This book was released on 2009 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Simulation of Power and Particle Flows in the NSTX Edge Plasma by :
Download or read book Simulation of Power and Particle Flows in the NSTX Edge Plasma written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We simulate edge plasmas in NSTX double-null divertor configurations with the UEDGE two-dimensional fluid code. The carbon impurity density in the core plasma and total radiated power increase with the core heating power and the magnitude of the physical and chemical sputtering in the divertor. Up/down plasma asymmetries are generated by classical cross-field particle drifts. With the standard toroidal magnetic field direction (ion (nabla)B drift toward the lower x-point) the highest density occurs at the lower inboard divertor plate and the highest heat flux at the upper outboard divertor plate. Simulations of 3-d edge plasma turbulence with the BOUT code show that anomalous radial transport at the outboard midplane should be similar in magnitude for NSTX and DIII-D.
Book Synopsis The Effect of Drifts on the DIII-D Boundary Plasma by :
Download or read book The Effect of Drifts on the DIII-D Boundary Plasma written by and published by . This book was released on 2002 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of ExB and diamagnetic drifts on the boundary plasma of a diverted tokamak is examined by comparing simulations obtained from the 2D fluid code UEDGE with data from the DIII-D tokamak. The effect of drifts on a single null L-mode configuration is determined by comparing the measurements with two simulations which are identical except that only one includes drifts. The dominant effect is seen on the high B-field side of the divertor where the plasma density is a factor of two higher when drifts are included. This effect occurs because a radial electric field associated with steep electron temperature radial gradients along the separatrix between the X-point and strike points drives a poloidal flow from the outer to inner divertor in the private region. The higher density yields higher radiation power, moving line radiation zones further off the divertor plate. The simulated profiles of both D{sub {alpha}} and CIII radiation obtained with drift effects included are more consistent with measurements. The drifts also affect the in/out asymmetry of both divertor heating power and divertor ion flux. The effect of drifts on the up/down asymmetry of double null plasma configurations is also considered, although not in as much detail. The up/down asymmetry of the divertor heat flux which is measured in double null plasmas on DIII-D is consistent with that obtained in UEDGE simulations which include the effect of drifts. Drift effects can be important in determining the profile of divertor heating powers, and the distribution of recycling neutrals, and therefore should be included in the design of divertor structures for future fusion devices.
Book Synopsis Simulation of Double-null Divertor Plasmas with the UEDGE Code by :
Download or read book Simulation of Double-null Divertor Plasmas with the UEDGE Code written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We describe recent modifications to the UEDGE code that enable us to simulate full double-null magnetic configurations. We present simulation results for magnetically balanced double- nulls, with and without asymmetries due to divertor recycling and cross-field drifts. Up/down electron temperature asymmetries due to recycling are weak for attached plasmas because the magnetic connection length is shorter than for comparable single-null plasmas. Cross-field drifts due to radial electric fields produce strong poloidal ion particle fluxes at the midplane in the SOL that can drive up/down asymmetries.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis DIII-D Data for Modeling the Scrape-off-layer Plasma by :
Download or read book DIII-D Data for Modeling the Scrape-off-layer Plasma written by and published by . This book was released on 1989 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: We are in the process of assembling a database of edge and divertor plasma parameters suitable for use in benchmarking tious 2D models of the scrape-off- layer (SOL) plasma. Also, we are using the Braams B2 code to derive transport coefficients for the edge plssma. In parallel, work is starting on an upgrade to the B2 code that includes padlel current flow and EXB drifts. These efforts are directed at increasing the confidence level of models of the tokamak edge plasma so that we can predict the effect of planned upgrades to DIII-D (e.g., the Advanced Divertor Program) and the performance of next generation machines such as CIT or ITER, where initial design studies show that plasma conditions at the divertor targets can have a large impact on the lifetime and cost of the machine. This report summarizes our recent progress in characterizing the DIII-D SOL plasma and in modeling these data with the the B2 code. Section I contains a brief description of the diagnostics available for characterizing the SOL plasma. In Section II we present our measurements of the SOL parameters for H-mode plasmas. This includes data showing how the divertor plasma parameters (n{sub e}(r), T{sub e}(r), and Q(r)) vary from ohmic to L-mode to H-mode, and power balance for quasi-stationary H-mode plasmas. Section III covers divertor-target heat-flux asymmetries for double and single null operation with forward and reversed toroidal field. In Section IV we show the scaling of L-mode parameters with neutral beam power, and Section V concludes with a summary of the results obtained from the Braams B2 SOL simulation code.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-12 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Impact of Edge Current Density and Pressure Gradient on the Stability of DIII-D High Performance Discharges by :
Download or read book Impact of Edge Current Density and Pressure Gradient on the Stability of DIII-D High Performance Discharges written by and published by . This book was released on 1997 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the major goals of advanced tokamak research is to develop plasma configurations with good confinement and improved stability at high [beta]. In DIII-D, various high performance configurations with H- and VH-mode edges have been produced. These include discharges with poloidal cross sections in the forms of dee and crecent shapes, single- and double-null divertors, and with various central magnetic shear profiles and current profile peakedness. All these discharges exhibit confinement in the outer plasma region which leads to a large edge pressure gradient and a large edge bootstrap current driven by this steep pressure gradient. These edge conditions often drive an instability near the edge region which can severely degrade the discharge performance. An understanding of this edge instability is essential to sustain an enhance discharge performance.
Book Synopsis INTERPRETIVE MODELING OF SIMPLE-AS-POSSIBLE-PLASMA DISCHARGES ON DIII-D USING THE OEDGE CODE. by :
Download or read book INTERPRETIVE MODELING OF SIMPLE-AS-POSSIBLE-PLASMA DISCHARGES ON DIII-D USING THE OEDGE CODE. written by and published by . This book was released on 2002 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recently a number of major, unanticipated effects have been reported in tokamak edge research raising the question of whether we understand the controlling physics of the edge. This report is on the first part--here focused on the outer divertor--of a systematic study of the simplest possible edge plasma--no ELMs, no detachment, etc.--for a set of 10 repeat, highly-diagnosed, single-null, divertor discharges in DIII-D. For almost the entire, extensive data set so far evaluated, the matches of experiment and model are so close as to imply that the controlling processes at the outer divertor for these simple plasma conditions have probably been correctly identified and quantitatively characterized in the model. The principal anomaly flagged so far relates to measurements of T{sub e} near the target, potentially pointing to a deficiency in our understanding of sheath physics in the tokamak environment.
Book Synopsis Plasma Surface Interactions in Controlled Fusion Devices by :
Download or read book Plasma Surface Interactions in Controlled Fusion Devices written by and published by . This book was released on 1978 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Modeling the Neutral Density in the Edge of the DIII-D Plasma by : Weston Monroe Stacey
Download or read book Modeling the Neutral Density in the Edge of the DIII-D Plasma written by Weston Monroe Stacey and published by . This book was released on 1999 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Simulation of Main-Chamber Recycling in DIII-D with the UEDGE Code by : J. Watkins
Download or read book Simulation of Main-Chamber Recycling in DIII-D with the UEDGE Code written by J. Watkins and published by . This book was released on 2006 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report demonstrates a computer simulation model for single-null diverted plasma configurations that include simultaneous interaction of the scrape-off layer (SOL) plasma with toroidally symmetric main-chamber limiter surfaces and divertor plate surfaces. The simulations use the UEDGE code which treats the SOL plasma and recycled neutrals as two-dimensional toroidally symmetric fluids. The spatial domain can include field lines that intersect main chamber surfaces in the far scrape-off layer, which allows the model to include simultaneous plasma contact with both divertor and main chamber targets. Steady-state simulation results for low-density L-mode plasma discharges in DIII-D show that total core fueling increases by about 70 percent when the separatrix-baffle gap is reduced from 6 cm to 3 cm. The additional core fueling is due to neutrals which originate from the ion particle flux incident on the upper outer divertor baffle.
Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Enhanced Scrape-off Layer Plasma in DIII-D Double-null Discharges by :
Download or read book Enhanced Scrape-off Layer Plasma in DIII-D Double-null Discharges written by and published by . This book was released on 1994 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, the authors examine a denser and broader scrape-off layer (SOL) plasma, first seen in VH mode, in the DIII-D tokamak. The enhanced SOL appears in many types of double-null (DN) discharges and is not a property of VH-mode only. The DN enhanced SOL density and temperature profiles exhibit a 5--6 cm broad profile outside the separatrix. For DN and single-null (SN) boundary geometry with similar core plasma conditions, the enhanced SOL is only observed in high triangularity discharges. The origin of the enhanced SOL is, however, not yet understood.
Download or read book Fusion Technology written by and published by . This book was released on 2001 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fusion Technology 1996 by : C. Varandas
Download or read book Fusion Technology 1996 written by C. Varandas and published by Elsevier. This book was released on 2012-12-02 with total page 1057 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of these proceedings was to provide a platform for the exchange of information on the design, construction and operation of fusion experiments. The technology which is being developed for the next step devices and fusion reactors was also covered.
