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in creator/contributor: "KRASHENINNIKOV,S"  
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Large plasma pressure perturbations and radial convective transport in a tokamak

Description: Strongly localized plasma structures with large pressure inhomogeneities (such as plasma blobs in the scrape-off-layer (SOL)/shadow regions, pellet clouds, ELMs) observed in the tokamaks, stellarators and linear plasma devices. Experimental studies of these phenomena reveal striking similarities including more convective rather than diffusive radial plasma transport. We suggest that rather simple models can describe many essentials of blobs, ELMs, and pellet clouds dynamics. The main ingredient… more
Date: February 4, 2004
Creator: Krasheninnikov, S.; Ryutov, D. & Yu, G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Self-similar variables and the problem of nonlocal electron heat conductivity

Description: Self-similar solutions of the collisional electron kinetic equation are obtained for the plasmas with one (1D) and three (3D) dimensional plasma parameter inhomogeneities and arbitrary Z{sub eff}. For the plasma parameter profiles characterized by the ratio of the mean free path of thermal electrons with respect to electron-electron collisions, {gamma}{sub T}, to the scale length of electron temperature variation, L, one obtains a criterion for determining the effect that tail particles with mo… more
Date: October 1, 1993
Creator: Krasheninnikov, S.I. & Bakunin, O.G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Simulation of Large Parallel Plasma Flows in the Tokamak SOL Driven by Cross-Field Transport Asymmetries

Description: Large-Mach-number parallel plasma flows in the single-null SOL of different tokamaks are simulated with multi-fluid transport code UEDGE. The key role of poloidal asymmetry of cross-field plasma transport as the driving mechanism for such flows is discussed. The impact of ballooning-like diffusive and convective transport and plasma flows on divertor detachment, material migration, impurity flows, and erosion/deposition profiles is studied. The results on well-balanced double null plasma modeli… more
Date: June 6, 2006
Creator: Pigarov, A Y; Krasheninnikov, S I; LaBombard, B & Rognlien, T D
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Partner: UNT Libraries Government Documents Department
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Dust-Particle Transport in Tokamak Edge Plasmas

Description: Dust particulates in the size range of 10nm-100{micro}m are found in all fusion devices. Such dust can be generated during tokamak operation due to strong plasma/material-surface interactions. Some recent experiments and theoretical estimates indicate that dust particles can provide an important source of impurities in the tokamak plasma. Moreover, dust can be a serious threat to the safety of next-step fusion devices. In this paper, recent experimental observations on dust in fusion devices ar… more
Date: September 12, 2005
Creator: Pigarov, A Y; Krasheninnikov, S I; Soboleva, T K & Rognlien, T D
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Transport of Dust Particles in Tokamak Devices

Description: Recent advances in the dust transport modeling in tokamak devices are discussed. Topics include: (1) physical model for dust transport; (2) modeling results on dynamics of dust particles in plasma; (3) conditions necessary for particle growth in plasma; (4) dust spreading over the tokamak; (5) density profiles for dust particles and impurity atoms associated with dust ablation in tokamak plasma; and (6) roles of dust in material/tritium migration.
Date: June 6, 2006
Creator: Pigarov, A Y; Smirnov, R D; Krasheninnikov, S I; Rognlien, T D & Rozenberg, M
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Plasma Physics Regimes in Tokamaks with Li Walls

Description: Low recycling regimes with a plasma limited by a lithium wall surface suggest enhanced stability and energy confinement, both necessary for tokamak reactors. These regimes could make ignition feasible in compact tokamaks. Ignited Spherical Tokamaks (IST), self-sufficient in the bootstrap current, are introduced as a necessary step for development of the physics and technology of power reactors.
Date: August 21, 2003
Creator: Zakharo, L. E.; Gorelenkov, N. N.; White, R. B.; Krasheninnikov, S. I. & Pereverzev, G. V.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Observation of Self-Mitigation of a Density Limit Disruption in DIII-D

Description: OAK-B135 Density limit disruptions set an upper bound on the electron density in tokamaks and are important for future reactor-size tokamaks, which will typically need to operate at high densities to achieve ignition. In the standard picture of disruptions, a large MHD mode, or combination of MHD modes, causes a mixing of previously nested magnetic flux surfaces across much of the profile. Rapid heat and particle transport across the separatrix result, and the thermal energy of the discharge is… more
Date: August 2003
Creator: Gray, D. S.; Hollmann, E. M.; Whyte, D. G.; Pigarov, A. Yu.; Krasheninnikov, S. I.; Boedo, J. A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Multi-fluid code simulations including anomalous non-diffusive transport of plasma and impurities in the tokamak SOL

Description: Fast intermittent transport has been observed in the scrape-off layer (SOL) of major tokamaks including Alcator C-Mod, DIII-D, and NSTX. This kind of transport is not diffusive but rather convective. It strongly increases plasma flux to the chamber walls and enhances the recycling of neutral particles in the main chamber. We discuss anomalous cross-field convection (ACFC) model for impurity and main plasma ions and its relation to intermittent transport events, i.e. plasma density blobs and hol… more
Date: November 25, 2003
Creator: Pigarov, A. Yu; West, W. P.; Soukhanovskii, V.; Rognlien, T. D.; Maingi, R.; Lipschultz, B. 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
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Status of Issues in U.S. Edge-Plasma Research and Priority Topics for the Next Five Years

Description: The Edge Coordinating Committee (ECC) was formed in July 14-15, 2004 when OFES Theory Team invited 14 plasma researchers to a two-day meeting in Germantown, MD to discuss the state of edge-plasma research in the U.S. with a focus on theory and modeling (see http://www.mfescience.org/ecc/ ecc/). At that time, OFES tasked the ECC with providing, in about a six month period, a report on the present status of key issues in this area together with a roadmap of what range of activities should be unde… more
Date: March 16, 2005
Creator: Bateman, G.; Chang, C.; Fenstermacher, M.; Guzdar, P.; Hahm, T. S.; Krasheninnikov, S. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Intermittent Convection in the Boundary of DIII-D

Description: Intermittent plasma objects (IPOs) featuring higher pressure than the surrounding plasma, and responsible for {approx}50% of the E x B{sub T} radial transport, are observed in the scrape-off layer (SOL) and edge of the DIII-D tokamak. The skewness of probe and BES intermittent data suggest IPO formation at or near the last closed flux surface (LCFS) and the existence of hole-IPO pairs. The particle content of the IPOs at the LCFS is linearly dependent on the discharge density, however, when nor… more
Date: June 1, 2002
Creator: Boedo, J. A.; Rudakov, D. L.; Colchin, R. J.; Moyer, R. A.; Krasheninnikov, S.; Whyte, D. G. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Continuum Edge Gyrokinetic Theory and Simulations

Description: The following results are presented from the development and application of TEMPEST, a fully nonlinear (full-f) five dimensional (3d2v) gyrokinetic continuum edge-plasma code. (1) As a test of the interaction of collisions and parallel streaming, TEMPEST is compared with published analytic and numerical results for endloss of particles confined by combined electrostatic and magnetic wells. Good agreement is found over a wide range of collisionality, confining potential, and mirror ratio; and th… more
Date: January 9, 2007
Creator: Xu, X. Q.; Xiong, Z.; Dorr, M. R.; Hittinger, J. A.; Bodi, K.; Candy, J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Dust Studies in DIII-D Tokamak

Description: Studies of submicron dust using Mie scattering from Nd:YAG lasers and video data of micron to sub-millimeter sized dust on DIII-D tokamak have provided the first data of dust sources and transport during tokamak discharges. During normal operation on DIII-D dust observation rates are low, a few events per discharge or less. The net carbon content of the dust corresponds to a carbon atom density a few orders of magnitude below the core impurity density. Statistical analysis of Mie data collected… more
Date: April 15, 2008
Creator: Rudakov, D. L.; West, W. P.; Groth, M.; Yu, J. H.; Boedo, J. A.; Bray, B. D. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Migration of Artificially Introduced Micron Size Carbon Dust in the DIII-D Divertor

Description: Migration of pre-characterized carbon dust in a tokamak environment was studied by introducing about 30 milligrams of dust flakes 5-10 {micro}m in diameter in the lower divertor of DIII-D using the DiMES sample holder. The dust was exposed to high power ELMing Hmode discharges in lower-single-null magnetic configuration with the strike points swept across the divertor floor. When the outer strike point (OSP) passed over the dust holder exposing it to high particle and heat fluxes, part of the d… more
Date: May 15, 2006
Creator: Rudakov, D.; West, W.; Wong, C.; Brooks, N.; Evans, T.; Fenstermacher, M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Dust Measurements in Tokamaks

Description: Dust production and accumulation impose safety and operational concerns for ITER. Diagnostics to monitor dust levels in the plasma as well as in-vessel dust inventory are currently being tested in a few tokamaks. Dust accumulation in ITER is likely to occur in hidden areas, e.g. between tiles and under divertor baffles. A novel electrostatic dust detector for monitoring dust in these regions has been developed and tested at PPPL. In DIII-D tokamak dust diagnostics include Mie scattering from Nd… more
Date: April 23, 2008
Creator: Rudakov, D.; Yu, J.; Boedo, J.; Hollmann, E.; Krasheninnikov, S.; Moyer, R. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Transport by Intermittency in the Boundary of the Diii-D Tokamak

Description: A271 TRANSPORT BY INTERMITTENCY IN THE BOUNDARY OF THE DIII-D TOKAMAK. Intermittent plasma objectives (IPOs) featuring higher pressure than the surrounding plasma, are responsible for {approx} 50% of the E x B{sub T} radial transport in the scrape off layer (SOL) of the DIII-D tokamak in L- and H-mode discharges. Conditional averaging reveals that the IPOs are positively charged and feature internal poloidal electric fields of up to 4000 V/m. The IPOs move radially with E x B{sub T}/B{sup 2} ve… more
Date: November 1, 2002
Creator: Boedo, J. A.; Rudakov, D. L.; Moyer, R. A.; Mckee, G. R.; Colchin, R. J.; Schaffer, M. J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Far SOL Transport and Main Wall Plasma Interaction in DIII-D

Description: Far scrape-off layer (SOL) and near-wall plasma parameters in DIII-D depend strongly on the discharge parameters and confinement regime. In L-mode discharges cross-field transport increases with the average discharge density and flattens far SOL profiles, thus increasing plasma-wall contact. In H-mode between edge localized modes (ELMs), plasma-wall contact is generally weaker than in L-mode. During ELMs plasma fluxes to the wall increase to, or above the L-mode levels. Depending on the dischar… more
Date: October 19, 2004
Creator: Rudakov, D. L.; Boedo, J. A.; Moyer, R. A.; Stangeby, P. C.; Watkins, J. G.; Whyte, D. G. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Status and Plans for the National Spherical Torus Experimental Research Facility

Description: An overview of the research capabilities and the future plans on the MA-class National Spherical Torus Experiment (NSTX) at Princeton is presented. NSTX research is exploring the scientific benefits of modifying the field line structure from that in more conventional aspect ratio devices, such as the tokamak. The relevant scientific issues pursued on NSTX include energy confinement, MHD stability at high beta, non-inductive sustainment, solenoid-free start-up, and power and particle handling. I… more
Date: July 27, 2005
Creator: Columbia University
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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