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

Description: 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.
Partner: UNT Libraries Government Documents Department
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Magnetic shielding of neutral beam sources in mirror fusion test facility

Description: 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.
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

Description: 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.
Partner: UNT Libraries Government Documents Department
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MFTF-B physics requirements

Description: 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.
Partner: UNT Libraries Government Documents Department
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Streaming-plasma measurements in the Baseball II-T mirror experiment

Description: 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.
Partner: UNT Libraries Government Documents Department
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Power threshold for neutral beam current drive

Description: 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.
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.
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

Description: 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.
Partner: UNT Libraries Government Documents Department
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The National Spherical Torus Experiment (NSTX) Research Program and Progress Towards High Beta, Long Pulse Operating Scenarios

Description: A major research goal of the National Spherical Torus Experiment is establishing long-pulse, high-beta, high-confinement operation and its physics basis. This research has been enabled by facility capabilities developed over the last two years, including neutral-beam (up to 7 MW) and high-harmonic fast-wave heating (up to 6 MW), toroidal fields up to 6 kG, plasma currents up to 1.5 MA, flexible shape control, and wall preparation techniques. These capabilities have enabled the generation of pla… more
Date: October 15, 2002
Creator: Synakowski, E. J.; Bell, M. G.; Bell, R. E.; Bigelow, T.; Bitter, M.; Blanchard, W. et al.
Partner: UNT Libraries Government Documents Department
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A Summary of the results obtained in the LDRD project "Interaction of a magnetized plasma with structured surfaces- from devices to spacecraft"

Description: Our work was directed towards developing a basic understanding of a new class of phenomena: effects of surface structure on the processes in a magnetized plasma near surfaces and at some distances for them. The surface structures can be of various kinds: topographic features ranging from smooth �waviness� to a coarse �roughness,� non-uniformities of the secondary emission coefficient, dielectric impregnations into conducting surface, etc. The expected effects are strongest when the magnetic fie… more
Date: February 23, 1999
Creator: Cohen, R. H.; Porter, G. D. & Ryutov, D. D.
Partner: UNT Libraries Government Documents Department
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Progress Towards High Performance, Steady-state Spherical Torus

Description: Research on the Spherical Torus (or Spherical Tokamak) is being pursued to explore the scientific benefits of modifying the field line structure from that in more moderate aspect-ratio devices, such as the conventional tokamak. The Spherical Tours (ST) experiments are being conducted in various U.S. research facilities including the MA-class National Spherical Torus Experiment (NSTX) at Princeton, and three medium-size ST research facilities: Pegasus at University of Wisconsin, HIT-II at Univer… more
Date: October 2, 2003
Creator: Ono, M.; Bell, M. G.; Bell, R. E.; Bigelow, T.; Bitter, M.; Blanchard, W. et al.
Partner: UNT Libraries Government Documents Department
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Review of the neutral-beam current requirements for the Mirror Fusion Test Facility (MFTF)

Description: The techniques used to evaluate the beam-current requirements for MFTF are similar to those in previous studies but incorporate some improvements. In particular, we have enlarged the radial code BUILDUP to allow for a smaller radial grid and to improve the numerical accuracy; we have also improved the model of the atomic physics processes and the particle-equilibrium calculations. Also, a model of plasma containment that conserves energy as well as particles but does not include any effect of t… more
Date: August 4, 1978
Creator: Porter, G. D.; Coensgen, F. H.; Devoto, R. S.; Molvik, A. W.; Osher, J. F.; Shearer, J. W. et al.
Partner: UNT Libraries Government Documents Department
open access

Astron Program final report

Description: This report describes important experimental results obtained in the last two years of the Astron Program, an LLL controlled nuclear fusion program which terminated in 1973. Little theoretical work is included, but an extensive bibliography is given. (auth)
Date: August 25, 1975
Creator: Briggs, R. J.; Hester, R. E.; Porter, G. D.; Sherwood, W. A.; Spoerlein, R.; Stallard, B. W. et al.
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
Partner: UNT Libraries Government Documents Department
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Scaling and profiles of heat flux during partial detachment in DIII-D

Description: The authors examine the scaling of the peak divertor heat flux and total divertor plate power in partially detached divertor (PDD) discharges in DIII-D, as a function of input power and radiated power. The peak divertor heat flux in the attached plasma increases linearly with input power, but saturates in the detached cases. The total divertor plate power remains linear with input power in both the attached and detached plasmas. This is consistent with the fact that the heat flux peak is reduce… more
Date: August 1998
Creator: Lasnier, C. J.; Hill, D. N.; Allen, S. L.; Fenstermacher, M. E.; Porter, G. D.; Leonard, A. W. et al.
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
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