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OEDGE Modeling of the DIII-D H-Mode 13CH4 Puffing Experiment

Description: Use of carbon in tokamaks leads to a serious tritium retention issue due to co-deposition. To further investigate the processes involved, a detached ELMy H-mode (6.5 MW NBI) experiment was performed on DIII-D in which {sup 13}CH{sub 4} was puffed into the main vessel through the toroidally symmetric pumping plenum at the top of lower single-null discharges. Subsequently, the {sup 13}C content of tiles taken from the vessel wall was measured. The interpretive OEDGE code was used to model the res… more
Date: June 1, 2006
Creator: Elder, J. D.; McLean, A. G.; Stangeby, P. C.; Allen, S. L.; Boedo, J. C.; Bray, B. D. et al.
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Partner: UNT Libraries Government Documents Department
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Toroidally Asymmetric Distributions of Hydrocarbon (CD) Emission and Chemical Sputtering Sources in DIII-D

Description: Measurements in DIII-D show that the carbon chemical sputtering sources along the inner divertor and center post are toroidally periodic and highest at the upstream tile edge. Imaging with a tangentially viewing camera and visible spectroscopy were used to monitor the emission from molecular hydrocarbons (CH/CD) at 430.8 nm and deuterium neutrals in attached and partially detached divertors of low-confinement mode plasmas. In contrast to the toroidally periodic CD distribution, emission from de… more
Date: May 16, 2006
Creator: Groth, M.; Brooks, N. H.; Fenstermacher, M. E.; Lasnier, C. J.; McLean, A. G. & Watkins, J. G.
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Partner: UNT Libraries Government Documents Department
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DiMES Studies of Temperature Dependence of Carbon Erosion and Re-Deposition in the DIII-D Divertor

Description: A strong effect of a moderately elevated surface temperature on net carbon deposition and deuterium co-deposition in the DIII-D divertor was observed under detached conditions. A DiMES sample with a gap 2 mm wide and 18 mm deep was exposed to lower-single-null (LSN) L-mode plasmas first at room temperature, and then at 200 C. At the elevated temperature, deuterium co-deposition in the gap was reduced by an order of magnitude. At the plasma-facing surface of the heated sample net carbon erosion … more
Date: March 15, 2007
Creator: Rudakov, D. L.; Jacob, W.; Krieger, K.; Litnovsky, A.; Philipps, V.; West, W. P. et al.
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Partner: UNT Libraries Government Documents Department
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Edge Localized Mode Dynamics and Transport in the Scrape-Off Layer of the DIII-D Tokamak

Description: High temporal and spatial resolution measurements in the boundary of the DIII-D tokamak show that edge localized modes (ELMs) are produced in the low field side, are poloidally localized and are composed of fast bursts ({approx}20 to 40 {micro}s long) of hot, dense plasma on a background of less dense, colder plasma ({approx}5 x 10{sup 18} m{sup {+-}3}, 50 eV) possibly created by the bursts themselves. The ELMs travel radially in the scrapeoff layer (SOL), starting at the separatrix at {approx}… more
Date: December 3, 2004
Creator: Boedo, J. A.; Rudakov, D. L.; Hollmann, E.; Gray, D. S.; Burrell, K. H.; Moyer, R. A. et al.
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Partner: UNT Libraries Government Documents Department
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Spectroscopic Characterization and Simulation of Chemical Sputtering Using the DiMES Porous Plug Injector in DIII-D

Description: A self-contained gas injection system for the Divertor Material Evaluation System (DiMES) on DIII-D has been employed for in-situ study of chemical erosion in the tokamak divertor environment. The Porous Plug Injector (PPI) releases methane, a major component of molecular influx due to chemical sputtering of graphite, from the tile surface into the plasma at a controlled rate through a porous graphite surface. Perturbation to local plasma is minimized, while also simulating the immediate enviro… more
Date: May 15, 2006
Creator: McLean, A. G.; Davis, J. W.; Stangeby, P. C.; Brooks, N. H.; Whyte, D. G.; Allen, S. L. et al.
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Partner: UNT Libraries Government Documents Department
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ELM Suppression in Low Edge Collisionality H-Mode Discharges Using n=3 Magnetic Perturbations

Description: Using resonant magnetic perturbations with toroidal mode number n = 3, we have produced H-mode discharges without edge localized modes (ELMs) which run with constant density and radiated power for periods up to about 2550 ms (17 energy confinement times). These ELM suppression results are achieved at pedestal collisionalities close to those desired for next step burning plasma experiments such as ITER and provide a means of eliminating the rapid erosion of divertor components in such machines w… more
Date: July 11, 2005
Creator: Burrell, K. H.; Evans, T. E.; Doyle, E. J.; Fenstermacher, M. E.; Groebner, R. J.; Leonard, A. W. et al.
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Partner: UNT Libraries Government Documents Department
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Compatibility of the Radiating Divertor with High Performance Plasmas in DIII-D

Description: A radiating divertor approach was successfully applied to high performance 'hybrid' plasmas [M.R. Wade, et al., Proc. 20th IAEA Fusion Energy Conf., Vilamoura, (2004)]. Our technique included: (1) injecting argon near the outer divertor target, (2) enhancing the plasma flow into the inner and outer divertors by a combination of particle pumping and deuterium gas puffing upstream of the divertor targets, and (3) isolating the inner divertor from the outer by a structure in the private flux regio… more
Date: May 18, 2006
Creator: Petrie, T. W.; Wade, M. R.; Brooks, N. H.; Fenstermacher, M. E.; Groth, M.; Hyatt, A. W. et al.
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Partner: UNT Libraries Government Documents Department
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Halo recycler for the Tandem Mirror Experiment Upgrade

Description: The halow recycler is a mechanical device on the Tandem Mirror Experiment Upgrade (TMX-U) that is designed to increase the density at the plasma edge providing enhanced shielding of the core plasma from background neutrals. Each recycler body, which consists of coaxial annular cylinders and a adjacent plenum closely follows the magnetic flux tubes in the transition region of TMX-U. Each plenum is provided with gas feed and pressure measurement systems as well as Langmuir probes. This paper desc… more
Date: November 14, 1985
Creator: Brooksby, C. A.; Allen, S. L.; Pedrotti, L. R.; Simonen, T. C.; Wood, B. E.; Hsu, W. L. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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PISCES and ALT-II: Juelich PSI papers

Description: This publication comprises papers from the PISCES and ALT-II Programs at UCLA which were presented at the International Plasma Surface Interactions Meeting held in Juelich, FRG, on May 2-6, 1988. A list of publications from the PISCES and ALT-II contained in this report are: Deuterium pumping and erosion behavior of selected graphite materials under high flux plasma bombardment in PISCES; Erosion and redeposition behavior of selected NET-candidate materials under high-flux hydrogen, deuterium p… more
Date: August 1, 1988
Creator: Conn, R. W.; Hirooka, Y.; LaBombard, B.; Moyer, R.; Goebel, D. M.; Leung, W. K. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Physics of the L-mode to H-mode transition in tokamaks

Description: Combined theoretical and experimental work has resulted in the creation of a paradigm which has allowed semi-quantitative understanding of the edge confinement improvement that occurs in the H-mode. Shear in the E {times} B flow of the fluctuations in the plasma edge can lead to decorrelation of the fluctuations, decreased radial correlation lengths and reduced turbulent transport. Changes in the radial electric field, the density fluctuations and the edge transport consistent with shear stabil… more
Date: July 1, 1992
Creator: Burrell, K. H.; Carlstrom, T. N.; Gohil, P.; Groebner, R. J.; Kim, J.; Osborne, T. H. et al.
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Partner: UNT Libraries Government Documents Department
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Enhanced Scrape-Off Layer Plasma in DIII-D Double-Null Discharges

Description: 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 discharge… more
Date: July 1, 1994
Creator: Watkins, J. G.; Jong, R. A. & Moyer, R. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Edge Localized Mode Control in DIII-D Using Magnetic Perturbation-Induced Pedestal Transport Changes

Description: Edge localized mode (ELM) control is a critical issue for ITER because the impulsive power loading from ELMs is predicted to limit the divertor lifetime to only a few hundred full-length pulses. Consequently, a technique that replaces the ELM-induced transport with more continuous transport while preserving the H-mode pedestal height and core performance would significantly improve the viability of ITER. One approach is to use edge resonant magnetic perturbations (RMPs) to enhance pedestal tran… more
Date: September 27, 2006
Creator: Moyer, R. A.; Burrell, K. H.; Evans, T. E.; Fenstermacher, M. E.; Joseph, I.; Osborne, T. H. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Observation of Dust in DIII-D Divertor and SOL by Visible Imaging

Description: Dust is commonly found in fusion devices. Though generally of no concern in the present day machines, dust may pose serious safety and operational concerns for ITER. Micron-size dust usually dominates the samples collected from tokamaks. During a plasma discharge micron-size dust particles can become highly mobile and travel over distances of a few meters. Once inside the plasma, dust particles heat up to over 3000 K and emit thermal radiation that can be detected by visible imaging techniques.… more
Date: April 2, 2007
Creator: Rudakov, D. L.; West, W. P.; Groth, M.; Yu, J. H.; Wong, C. C.; Boedo, J. A. et al.
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Partner: UNT Libraries Government Documents Department
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A Comparison of Radiating Divertor Behavior in Single- and Double-Null Plasmas in DIII-D

Description: 'Puff and pump' radiating divertor scenarios, applied to both upper single-null (SN) and double-null (DN) H-mode plasmas, result in a 30-60% increase in radiated power with little or no decrease in {tau}{sub E}. Argon was injected into the private flux region of the upper divertor, and plasma flow into the upper divertor was enhanced by a combination of deuterium gas puffing upstream of the divertor targets and particle pumping at the targets. For the same constant deuterium injection rate, arg… more
Date: March 25, 2008
Creator: Petrie, T. W.; Brooks, N. H.; Fenstermacher, M. E.; Groth, M.; Hyatt, A. W.; Isler, R. C. et al.
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Partner: UNT Libraries Government Documents Department
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Edge Stability and Transport Control with Resonant Magnetic Perturbations in Collisionless Tokamak Plasmas

Description: A critical issue for fusion plasma research is the erosion of the first wall of the experimental device due to impulsive heating from repetitive edge magneto-hydrodynamic (MHD) instabilities known as 'edge-localized modes' (ELMs). Here, we show that the addition of small resonant magnetic field perturbations completely eliminates ELMs while maintaining a steady-state high-confinement (H-mode) plasma. These perturbations induce a chaotic behavior in the magnetic field lines, which reduces the ed… more
Date: June 13, 2006
Creator: Evans, T. E.; Moyer, R. A.; Burrell, K. H.; Fenstermacher, M. E.; Joseph, I.; Leonard, A. W. et al.
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Partner: UNT Libraries Government Documents Department
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Suppression of Large Edge Localized Modes in High Confinement DIII-D Plasmas With a Stochastic Magnetic Boundary

Description: OAK-B135 A stochastic magnetic boundary, produced by an externally applied edge resonant magnetic perturbation, is used to suppress large edge localized modes (ELMs) in high confinement (H-mode) plasmas. The resulting H-mode displays rapid, small oscillations with a bursty character modulated by a coherent 130 Hz envelope. The H-mode transport barrier is unaffected by the stochastic boundary. The core confinement of these discharges is unaffected, despite a three-fold drop in the toroidal rotat… more
Date: November 1, 2003
Creator: Evans, T. E.; Moyer, R. A.; Thomas, P. R.; Watkins, J. G.; Osborne, T. H.; Boedo, J. A. et al.
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Partner: UNT Libraries Government Documents Department
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Comparison of Elm Pulse Propagation in the Diii-D Sol and Divertors With an Ion Convection Model

Description: OAK-B135 Results from dedicated ELM experiments, performed in DIII-D with fast diagnostics to measure the evolution of Type-I ELM effects in the SOL and divertor, are compared with a simple ion convection model and with initial time-dependent UEDGE simulations. Delays between ELM effects observed in the inner versus the outer divertor regions in the experiments scale, as a function of density, with the difference in ion convection time along field lines from the outer midplane to the divertor t… more
Date: August 1, 2003
Creator: Fenstermacher, M. E.; Porter, G. D.; Leonard, A. W.; Brooks, N. H.; Boedo, J. A.; Colchin, R. J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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