Download or read book A Two dimensional Kinetic Model of the Scrape off Layer of a Diverted Plasma with a Private Flux Region written by Peter James Catto and published by . This book was released on 1994 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High field Side Scrape off Layer Density Profiles Inferred from D alpha Emission on Alcator C Mod written by Christopher James Boswell and published by . This book was released on 2004 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements from an inner wall mounted scanning Langmuir probe and modelling of D[alpha] emission show a sharp fall-off of plasma density in the inboard private flux region. D[alpha] emission is modelled using a one dimensional space, two dimensional velocity kinetic neutral code in order to track the changes in the density profile while the magnetic topology is changed from single to double null. A sharp density decay is observed to track with the location of the secondary separatrix. The presented data is consistent with a lower level of cross-field transport on field lines in the private flux region restricted to the high-field side when compared to cross-field transport on field lines in the low-field side scrape-off layer.

Download or read book Scaling Study of Scrape off Layer Plasma by Two Dimensional Transport Simulation written by Sanae Inoue Itoh and published by . This book was released on 1989 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Two dimensional Analysis on Limiter divertor Transition in Scrape off Layer Plasmas written by N. Ueda and published by . This book was released on 1988 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Simulation Study of Scalings in Scrape off Layer Plasma by Two Dimensional Transport Code written by Sanae Inoue Itoh and published by . This book was released on 1990 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Plasma Physics and Controlled Nuclear Fusion Research written by and published by . This book was released on 1991 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book UEDGE and DEGAS Modeling of the DIII D Scrape off Layer Plasma Revision 1 written by and published by . This book was released on 1994 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents work to develop benchmarked theoretical models of scrape-off-layer (SOL) characteristics in diverted tokamaks by comparing shot simulations using the UEDGE plasma fluid and DEGAS neutral transport codes to measurements of the DIII-D SOL plasma. The experimental data include the radial profiles of n{sub e} T{sub e}, and T{sub i}, the divertor exhaust power, the intensity of H{sub {alpha}} emission, and profiles of the radiated power. A very simple model of the anomalous perpendicular transport rates produces consistency between the calculated and measured radial profiles of the divertor power, and of the midplane densities and temperatures. Experimentally, the measured exhaust power is now 80--90% of the input power. The simulated peak power on the outer leg of the divertor floor is now within 20% of the measured power. Various sensitivities of these comparisons to model assumptions are described. Finally, these benchmarked models have been used to examine the effects of various baffle configurations for the Radiative Divertor Upgrade in DIII-D.

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 Coupled Two dimensional Edge Plasma and Neutral Gas Modeling of Takamak Scrape off layers written by Rajesh Maingi and published by . This book was released on 1992 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics Briefs written by and published by . This book was released on 1992 with total page 812 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book UEDGE and DEGAS Modeling of the DIII D Scrape off Layer Plasma written by and published by . This book was released on 1994 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents the results of work to develop benchmarked theoretical models of scrape-off-layer (SOL) characteristics in diverted tokamaks by comparing shot simulations using the UEDGE plasma fluid and DEGAS Monte-Carlo neutral particle transport codes to measurements of the DIII-D SOL plasma. The available experimental data include the radial profiles of electron density and temperature, the ion temperature, the divertor exhaust power, the intensity of H{sub {alpha}} emission, and profiles of the radiated power. A very simple model of the anomalous perpendicular transport rates produces consistency between the calculated and measured radial profiles of the divertor power, and of the midplane densities and temperatures. Experimentally, measured exhaust power is now typically 80--90% of the input power. The simulated peak power on the outer leg of the divertor floor is now within about 20% of the measured power. Various sensitivities of the simulation and measurement comparisons to model assumptions are described. Finally, these benchmarked models have been used to examine the effects of various baffle configurations for the Radiative Divertor Upgrade in DIII-D.

Download or read book Scrape Off Layer Transport and Deposition Studies in DIII D written by S. Allen and published by . This book was released on 2006 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: Trace {sup 13}CH{sub 4} injection experiments into the main scrape-off layer of low density L-mode and high-density H-mode plasmas have been performed in the DIII-D tokamak [Luxon{_}NF02] to mimic the transport and deposition of carbon arising from a main chamber sputtering source. These experiments indicated entrainment of the injected carbon in plasma flow in the main SOL, and transport toward the inner divertor. Ex-situ surface analysis showed enhanced {sup 13}C surface concentration at the corner formed by the divertor floor and the angled target plate of the inner divertor in L-mode; in H-mode, both at the corner and along the surface bounding the private flux region inboard of the outer strike point. Interpretative modeling was made consistent with these experimental results by imposing a parallel carbon ion flow in the main SOL toward the inner target, and a radial pinch toward the separatrix. Predictive modeling carried out to better understand the underlying plasma transport processes suggests that the deuterium flow in the main SOL is related to the degree of detachment of the inner divertor leg. These simulations show that carbon ions are entrained with the deuteron flow in the main SOL via frictional coupling, but higher charge state carbon ions may be suspended upstream of the inner divertor X-point region due to balance of the friction force and the ion temperature gradient.

Download or read book Investigation of scrape off layer up down asymmetries in diverted plasmas in TEXT Upgrade written by Xavier Pierre Gilles Bonnin and published by . This book was released on 1998 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Summary of UNM Work on Edge Plasma Modelling written by and published by . This book was released on 1996 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: The B2 two dimensional edge plasma code has found widespread application in modelling scrape-off layer and divertor plasma conditions for ITER and CIT (BPX). The transport physics in B2 consists of the so-called standard model that employs 2D Braginskii equations for the background plasma, anomalous cross-field transport coefficients, and classical along-field transport coefficients computed in the straight cylinder approximation. Although the code displays acceptable convergence characteristics for the class of problems of interest in ITER and CIT applications, it is remarkably resistant to improvements in the physics model. That is, extensions to including the symmetry breaking drift flows and wall or divertor plate generated impurity species in the code have not met with success - satisfactory solution convergence has not been achieved in various test problems. Given that the drift flows have been identified as being an important component of any fluid model that attempts to reconcile computational results with experimental observations and that control of impurities is vitally important in present and subsequent generations of high power machines, successful numerical models of edge plasmas must be clearly robust enough to handle a significantly expanded physical model.

Download or read book Axisymmetric Scrape off Plasma Transport written by and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The two-dimensional flow of a collision dominated hydrogen scrape-off plasma in an axisymmetric tokamak is examined. This flow is described by a set of equations which contain the dominant terms in a maximal ordering appropriate to high density experimental divertors and reactor scrape-off plasmas. Comparison of the theory to estimates of scrape-off parameters in the Doublet III expanded boundary plasmas suggests that analysis of classical and neoclassical processes alone may be sufficient to predict plasma transport in high density scrape-off plasmas of practical importance.

Download or read book Modeling The Effect of Drifts on the Edge Scrape Off Layer and Divertor Plasma in DIII D written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Simulations of plasmas with a DIII-D shape indicate plasma drifts are important at power levels near the L- to H-mode plasma transition. In addition to enhancing plasma flows in the divertor region, drifts are found to play a key role in establishing highly sheared radial electric fields in the edge of the confined plasma, for the physics of the high confinement operating mode (H-mode). Measurements of the plasma structure in the vicinity of the X-point of DIII-D indicate the importance of drifts on plasma flow between the scrape-off layer (SOL) and closed field lines. The large electric fields provide large flows around the X-point, and these are conjectured to play a role in the transition from L- to H-mode confinement. These results indicate the relevance of modeling the edge and SOL plasmas of present tokamak devices using models which include E x B, (nabla)B, and pressure gradient drifts. The results of simulation of specific DIII-D discharges is reported in this paper. They start with discussion of the simulation of an Ohmic discharge in Section 2, including a study of the effect of varying several operational parameters. Simulation of a higher triangularity L-mode discharge is discussed in Section, and a summary is given in Section 4.

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.