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in creator/contributor: "Porter, G. D."

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Directions for possible upgrades of the Mirror Fusion Test Facility (MFTF)

The Mirror Fusion Test Facility (MFTF) may be upgraded by extending the time of plasma sustenance in an approach to steady-state operation and/or by increasing the neutral-beam injection energy. Some parameter bounds for these upgrades are discussed as they relate to a definition of the required neutral-beam development.

Date: December 20, 1977

Creator: Damm, C. C.; Coensgen, F. H.; Devoto, R. S.; Molvik, A. W.; Porter, G. D.; Shearer, J. W. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Practical aspects of a 2-D edge-plasma model

The poloidal divertor configuration is considered the most promising solution to the particle and energy exhaust problem for a tokamak reactor. The scrape-off layer plasma surrounding the core and the high-recycling plasma near the divertor plates can be modelled by fluid equations for particle, momentum and energy transport. A numerical code (B2) based on a two-dimensional multi-fluid model has been developed for the study of edge plasmas in tokamaks. In this report we identify some key featur… more

Date: July 1, 1989

Creator: Rensink, M. E.; Hill, D. N.; Porter, G. D.; Braams, B. J. (Lawrence Livermore National Lab., CA (USA) & Princeton Univ., NJ (USA). Plasma Physics Lab.)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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

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.

Item Type: Article

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

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.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Compatibility of the Radiating Divertor with High Performance Plasmas in DIII-D

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.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Spatial dependence of the sheath power transmission factor in DIII-D

The spatial dependence of the power transmission factor, d, associated with an ion-electron pair passing through the sheath at the DIII-D divertor plate has been determined by sweeping the edge plasma across Langmuir probe detectors. Our results show that d decreases from the classically expected value of eight near the low density edge of the scrape-off-layer plasma to values less than unity at the peak of the profile. 13 refs., 16 figs.

Date: February 1, 1991

Creator: Futch, A. H.; Hill, D. N.; Porter, G. D.; Matthews, G.F. (UKAEA Culham Lab., Abingdon (UK)) & Buchenauer, D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Negative tandem mirror

A tandem mirror configuration can be created by combining hot electron end cell plasmas with neutral beam pumping. A region of large negative potential formed in each end cell confines electrons in the central cell. The requirement of charge neutrality causes the central cell potential to become negative with respect to ground in order to confine ions as well as electrons. We discuss the method of producing and calculating the desired axial potential profile, and show the calculated axial poten… more

Date: November 30, 1981

Creator: Poulsen, P.; Allen, S. L.; Casper, T. A.; Grubb, D. P.; Jong, R. A.; Nexsen, W. E. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Design and development of neutral beam module components

The Mirror Fusion Test Facility (MFTF) injection system consists of twenty 20 keV start-up, and twenty-four 80 keV sustaining neutral beam source modules. The neutral beam modules are mounted in four clusters equally spaced around the waist of the vacuum vessel which contains the superconducting magnets. A module is defined here as an assembly consisting of a beam source and the interfacing components between that beam source and the vacuum chamber. Six major interfacing components are the subj… more

Date: November 13, 1979

Creator: Holl, P. M.; Bulmer, R. H.; Dilgard, L. W.; Horvath, J. A.; Molvik, A. W.; Porter, G. D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Plasma modeling of MFTF-B and the sensitivity to vacuum conditions

The Mirror Fusion Test Facility (MFTF-B) is a large tandem mirror device currently under construction at Lawrence Livermore National Laboratory. The completed facility will consist of a large variety of components. Specifically, the vacuum vessel that houses the magnetic coils is basically a cylindrical vessel 60 m long and 11 m in diameter. The magnetics system consists of some 28 superconducting coils, each of which is located within the main vacuum vessel. Twenty of these coils are relativel… more

Date: September 12, 1984

Creator: Porter, G. D. & Rensink, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Magnetic shielding of neutral beam sources in mirror fusion test facility

The magnetic shields of the Mirror Fusion Test Facility neutral beam sources must keep the inner magnetic field below 0.15 mT inside an unsymmetrical ambient magnetic field of 0.05 to 1.5 T. Numerical computations and 1/10th-scale experiments were used to arrive at a three-layer shield design consisting of two thin nickel-iron alloy shells inside a thick mild steel shell. A 1/10th-scale prototype test confirmed the final design.

Date: August 15, 1979

Creator: Shearer, J. W.; Cutler, T. A.; Dilgard, L. W.; Fabyan, J.; Holl, P. M.; Porter, G. D. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Proposed tandem mirror research program for FY87 presented to the MFAC subcommittee on mirror research, July 8-9, 1986

We have reexamined the goal of approx.10/sup 13/ cm/sup -3/ central-cell density with end-plugging and reconfirmed its importance as a test of thermal barrier end-plugging performance in either Tara or TMX-U. We conclude that, when all factors are considered including the impact on other programs interlinked with LLNL in the present OFE budget, the lowest cost approach to have a fair chance to meet this goal is to extend Tara operation for the full FY87. Continuation of TMX-U operation in FY87,… more

Date: July 23, 1986

Creator: Baldwin, D. E.; Correll, D. L.; Fowler, T. K.; Grubb, D. P.; Hershkowitz, N.; Porter, G. D. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Neutral beam current drive scaling in DIII-D

Neutral beam current drive scaling experiments have been carried out on the DIII-D tokamak at General Atomics. These experiments were performed using up to 10 MW of 80 keV hydrogen beams. Previous current drive experiments on DIII-D have demonstrated beam driven currents up to 340 kA. In the experiments reported here we achieved beam driven currents of at least 500 kA, and have obtained operation with record values of poloidal beta (epsilon..beta../sub p/ = 1.4). The beam driven current reporte… more

Date: March 1, 1989

Creator: Porter, G. D.; Bhadra, D. K.; Burrell, K. H.; Callis, R. W.; Colleraine, A. P.; Ferron, J. R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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MFTF-B physics requirements

The specifics of the physics requirements for the magnetic fields, diagnostics, particle and energy sources, and vacuum environment for the MFTF-B experiment are described. (MOW)

Date: March 25, 1981

Creator: Porter, G. D. & Thomassen, K. I.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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UEDGE and DEGAS modeling of the DIII-D scrape-off layer plasma. Revision 1

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 perpe… more

Date: May 1, 1994

Creator: Fenstermacher, M. E.; Porter, G. D.; Rensink, M. E.; Rognlien, T. D.; Allen, S. L.; Hill, D. N. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Scrape-off layer plasma modeling for the DIII-D tokamak

The behavior of the scrape-off layer (SOL) region in tokamaks is believed to play an important role determining the overall device performance. In addition, control of the exhaust power has become one of the most important issues in the design of future devices such as ITER and TPX. This paper presents the results of application of 2-D fluid models to the DII-D tokamak, and research into the importance of processes which are inadequately treated in the fluid models. Comparison of measured and s… more

Date: September 1, 1994

Creator: Porter, G. D.; Rognlien, T. D. & Allen, S. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Benchmarking UEDGE with DIII-D data

Comparisons between a 2-D fluid simulation of the scrape-off-layer (SOL) plasma of a diverted tokamak and experimental data from the DIII-D are shown. It is concluded that a simple diffusive model for perpendicular transport is consistent with the data. Discrepancies in the simulation suggest that impurity radiation may be playing a significant role in the experiment, and that further work is required to understand hydrogen recycling at the divertor.

Date: September 1, 1993

Creator: Porter, G. D.; Fenstermacher, M.; Rensink, M. E.; Rognlien, T. D.; Groebner, R.; Leonard, A. et al.

Item Type: 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

No Description Available.

Date: July 15, 2003

Creator: Groth, M.; Porter, G. D.; Petrie, T. W.; Fenstermacher, M. E. & Brooks, N. H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Streaming-plasma measurements in the Baseball II-T mirror experiment

The warm plasma from a deuterium-loaded titanium washer gun, streaming along magnetic-field lines through the steady-state magnetic well of Baseball II, has been examined for its suitability in this experimental situation as a target plasma for hot-ion buildup experiments and for microinstability control. The gun was positioned near the magnetic axis outside the mirror region. Measurements were made with gridded, end-loss detectors placed outside the opposite mirror, a microwave interferometer,… more

Date: May 9, 1977

Creator: Damm, C. C.; Foote, J. H.; Futch, A. H.; Goodman, R. K.; Hornady, R. S.; Osher, J. E. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Power threshold for neutral beam current drive

For fully noninductive current drive in tokamaks using neutral beams, there is a power and density threshold condition, setting a minimum value for P{sup 3/2}/n{sup 2}. If this condition is not met, stationary state cannot occur, and a tokamak discharge will collapse. This is a consequence of the coupling between current and electron temperature, or between current drive efficiency and energy confinement time. 4 figs.

Date: October 2, 1989

Creator: Politzer, P. A. & Porter, G. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Effect of extended pulse length on the Mirror Fusion Test Facility (MFTF)

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: Report

Partner: UNT Libraries Government Documents Department

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Scrape-Off-Layer Flow Studies in Tokamaks: Final Report of LDRD Project 09-ERD-025

A summary is given of the work carried out under the LDRD project 09-ERD-025 entitled Scrape-Off-Layer Flow Studies in Tokamaks. This project has lead to implementation of the new prototype Fourier Transform Spectrometer edge plasma flow diagnostic on the DIII-D National Fusion Facility at General Atomics, acquisition of carbon impurity concentration and flow data, and demonstration that the resulting data compare reasonably well with LLNL's edge plasma transport code UEDGE. Details of the work… more

Date: November 21, 2011

Creator: Rognlien, T. D.; Allen, S. L.; Ellis, R. M.; Porter, G. D.; Nam, S. K.; Weber, T. R. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Edge Localized Mode Control in DIII-D Using Magnetic Perturbation-Induced Pedestal Transport Changes

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: Article

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

'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.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Pedestal, SOL and Divertor Plasma Properties in DIII-D RMP ELM-Suppressed Discharges at ITER Relevant Edge Collisionality

No Description Available.

Date: February 5, 2007

Creator: Fenstermacher, M. E.; Evans, T. E.; Moyer, R. A.; Porter, G. D.; Boedo, J. A.; Burrell, K. H. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department