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Radial Particle Flux in the SOL of DIII-D During ELMing H-Mode

Description: The radial particle flux in the scrape-off-layer (SOL) during ELMing H-mode is examined in DIII-D as a function of density. The global radial particle flux in the outboard far SOL is determined by a window frame technique. Between ELMs the outboard far SOL particle flux increases strongly with density but remains similar to the particle flux across the separatrix as estimated by the pedestal density and temperature gradients. At low density the steep density gradient of the pedestal extends up … more
Date: June 1, 2006
Creator: Leonard, A. W.; Boedo, J. A.; Groth, M.; Lipschultz, B. L.; Porter, G. D.; Rudakov, D. L. et al.
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Partner: UNT Libraries Government Documents Department
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Effect of extended pulse length on the Mirror Fusion Test Facility (MFTF)

Description: The requirements and effects of operating Mirror Fusion Test Facility (MFTF) experiments with neutral-beam pulse durations in the range from 0.5 s to steady state are reexamined. Two questions are examined: (1) what is the maximum neutral-beam duration into the MFTF if the latter is built as described in the conceptual design document, and (2) what is required (and at what cost) to permit neutral-beam injection periods of 30 s in the MFTF. In both cases, it is assumed that the required neutral-… more
Date: June 14, 1977
Creator: Porter, G. D.; Bulmer, R. H.; Goensgen, F. H.; Cummins, W. F.; Hornady, R. S. & Stone, R. R.
Item Type: Refine your search to only Report
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.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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HIGH TIME-RESOLVED, 2-D IMAGING OF TYPE-1 ELMs IN DIII-D USING A IMAGE-INTENSIFIED CID CAMERA

Description: The evolution of 2-D emission profiles of D{sub {alpha}} and C III during type-I ELMs has been investigated in DIII-D using a tangentially viewing gated, intensified charge-injected device (CID) camera. The measured CIII emission profiles indicate transient inner leg attachment with the arrival of the ELM heat pulse. The measured D{sub {alpha}} emission profiles during an ELM cycle show enhanced deuterium recycling during the deposition of the ELM particle pulse at the target, which suggests th… more
Date: June 1, 2002
Creator: Groth, M.; Fenstermacher, M. E.; Boedo, J. A.; Brooks, N. H.; Gray, D. S.; Lasnier, C. J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Analysis of particle flow in the DIII-D SOL and divertor

Description: The scrape-off layer (SOL) and divertor plasma in the DEEI-D tokamak has been modeled using the 2-D fluid code UEDGE. The resulting simulated plasmas are compared in detail with the numerous diagnostics available on the device. Good agreement is obtained between the experimental measurements and the simulations when relatively small values of the assumed anomalous perpendicular transport coefficients are used. We use a purely diffusive model for perpendicular transport, with transport coefficie… more
Date: June 20, 1995
Creator: Porter, G. D.; Rensink, M. & Rognlien, T.
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Partner: UNT Libraries Government Documents Department
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Modeling The Effect of Drifts on the Edge, Scrape-Off Layer, and Divertor Plasma in DIII-D

Description: 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 drif… more
Date: June 5, 2001
Creator: Porter, G. D.; Boedo, J. A.; Groebner, R. J.; Carlstrom, T. N.; Rognlien, T. D.; Rensink, M. E. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Investigation of Main-Chamber and Divertor Recycling in DIII-D Using Tangentially Viewing CID Cameras

Description: Measurements of the D{sub {alpha}} emission profiles from the divertor and main chamber region in DIII-D, performed in low-density L-mode, and low and high-density ELMy H-mode plasmas imply that core plasma fueling occurs through the divertor channel. Emission profiles of carbon, combined with UEDGE modeling of the L-mode plasmas, also suggests that chemical sputtering of carbon from the flux surface adjacent to the inner divertor walls, and temperature gradient forces in the scrape-off layer, … more
Date: June 16, 2003
Creator: Groth, M.; Porter, G. D.; Petrie, T. W.; Fenstermacher, M. E. & Brooks, N. H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Non-Inductive Current Drive Modeling Extending Advanced Tokamak Operation to Steady State

Description: A critical issue for sustaining high performance, negative central shear (NCS) discharges is the ability to maintain current distributions that are maximum off axis. Sustaining such hollow current profiles in steady state requires the use of non-inductively driven current sources. On the DIII-D experiment, a combination of neutral beam current drive (NBCD) and bootstrap current have been used to create transient NCS discharges. The electron cyclotron heating (ECH) and current drive (ECCD) syste… more
Date: June 6, 2000
Creator: Casper, T. A.; Lodestro, L. L.; Pearlstein, L. D.; Porter, G. D.; Murakami, M.; Lao, L. L. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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UEDGE modeling of the effect of divertor modifications on divertor performance

Description: The DIII'D upper divertor will be modified in late 1999 by installing a continuous dome in the private flux region with an independent pumping capability for the inner strike point. A ''bump'' on the inner cylinder also has been considered to enhance impurity and neutral control. Using the UEDGE code, we have examined the effect of this dome and the ''bump'' on core ionization and core impurity content. For typical parameters, results indicate that the planned divertor modifications enable deta… more
Date: June 23, 1999
Creator: Porter, G. D.; Rensink, M.; Roglien, T. & Wolf, N. S.
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Partner: UNT Libraries Government Documents Department
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Divertor characterization experiments

Description: Recent DIII-D experiments with enhanced Scrape-off Layer (SOL) diagnostics permit detailed characterization of the SOL and divertor plasma under various operating conditions. We observe two distinct plasma modes: attached and detached divertor plasmas. Detached plasmas are characterized by plate temperatures of only 1 to 2 eV. Simulation of detached plasmas using the UEDGE code indicate that volume recombination and charge exchange play an important role in achieving detachment. When the power … more
Date: June 18, 1996
Creator: Porter, G. D.; Allen, S.; Fenstermacher, M.; Hill, D.; Brown, M.; Jong, R. A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Spectroscopic measurements of impurity temperatures and parallel ion flows in the DIII-D divertor

Description: Impurity ion temperatures and parallel flow velocities in the DIII-D divertor have been measured from the shapes and shifts of visible spectral lines of C II, C III, and B II. Spectral multiplet patterns are analyzed by fitting them to theoretical profiles that incorporate exact calculations for the Zeeman/Paschen-Back effect. Ion temperatures range from 4--20 eV. Both normal flows toward the target plate and reversed flows away from the target plate are observed in the outer divertor leg; only… more
Date: June 1, 1998
Creator: Isler, R. C.; Brooks, N. H.; West, W. P.; Leonard, A. W.; McKee, G. R. & Porter, G. D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Measurements of flows in the DIII-D divertor by Mach probes

Description: First measurements of Mach number of background plasma in the DIII-D divertor are presented in conjunction with temperature T{sub e} and density n{sub e} using a fast scanning probe array. To validate the probe measurements, the authors compared the T{sub e}, n{sub e} and J{sub sat} data to Thomson scattering data and find good overall agreement in attached discharges and some discrepancy for T{sub e} and n{sub e} in detached discharges. The discrepancy is mostly due to the effect of large fluc… more
Date: June 1, 1998
Creator: Boedo, J. A.; Lehmer, R.; Moyer, R. A.; Watkins, J. G.; Porter, G. D.; Evans, T. E. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Effects of Divertor Geometry and Pumping on Plasma Performance on DIII-D

Description: This paper reports the status of an ongoing investigation to discern the influence of the divertor and plasma geometry on the confinement of both ELM-free and ELMing discharges in DIII-D. The ultimate goal is to achieve a high-performance core plasma which coexists with an advanced divertor plasma. The divertor plasma must reduce the heat flux to acceptable levels; the current technique disperses the heat flux over a wide area by radiation (a radiative divertor). To date, we have obtained our b… more
Date: June 1, 1997
Creator: Allen, S. L.; Hill, D. N. & Porter, G. D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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