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Analytical theory of ion-temperature-gradient instability

Description: The relationship between the threshold values of ion-temperature-gradient instabilities and the temperature parameters of plasmas is investigated analytically in slab and toroidal geometries separately. It is found that the threshold values increase rapidly when the ion temperature becomes much higher than the electron temperature. The change of the threshold vaues with respect to the ion temperature is quite similar for both geometric models. This finding is consistent with PLT observations. F… more
Date: January 19, 1982
Creator: Guo, S.; Shen, J.; Chen, L. & Tsai, S.T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Studies on Neutral Beam Injection into the SSPX Spheromak Plasma

Description: In the Sustained Spheromak Physics Experiment, (SSPX) ['Improved operation of the SSPX spheromak', R.D. Wood, D.N. Hill, E.B. Hooper, S. Woodruff1, H.S. McLean and B.W. Stallard, Nucl. Fusion 45 1582-1588 (2005)], plasmas with core electron temperatures reaching up to 500 eV at densities of 10{sup 20}/m{sup 3} have been sustained for several milliseconds, making them suitable as targets for neutral beam injection. High performance and further progress in understanding Spheromak plasma physics a… more
Date: October 19, 2007
Creator: Jayakumar, R; Pearlstein, L D; Casper, T A; Fowler, T K; Hill, D N; Hudson, B et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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NSTX: Facility/Research Highlights and Near Term Facility Plans

Description: The National Spherical Torus Experiment (NSTX) is a collaborative mega-ampere-class spherical torus research facility with high power heating and current drive systems and the state-of-the-art comprehensive diagnostics. For the 2008 experimental campaign, the high harmonic fast wave (HHFW) heating efficiency in deuterium improved significantly with lithium evaporation and produced a record central Te of 5 keV. The HHFW heating of NBI-heated discharges was also demonstrated for the first time wi… more
Date: November 19, 2008
Creator: Ono, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Investigation of the Electronic Structure of Solid Density Plasmas by X-Ray Scattering

Description: We present an improved analytical expression for the x-ray dynamic structure factor from a dense plasma which includes the effects of weakly bound electrons. This result can be applied to describe scattering from low to moderate Z plasmas, and it covers the entire range of plasma conditions that can be found in inertial confinement fusion experiments, from ideal to degenerate up to moderately coupled systems. We use our theory to interpret x-ray scattering experiments from solid density carbon … more
Date: May 19, 2003
Creator: Gregori, G; Glenzer, S H; Forest, F J; Kuhlbrodt, S; Redmer, R; Faussurier, G et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Effects of the Electron Energy Distribution Function on Modeled X-ray Spectra

Description: This paper presents the results of a broad investigation into the effects of the electron energy distribution function on the predictions of non-LTE collisional-radiative atomic kinetics models. The effects of non-Maxwellian and suprathermal (''hot'') electron distributions on collisional rates (including three-body recombination) are studied. It is shown that most collisional rates are fairly insensitive to the functional form and characteristic energy of the electron distribution function as … more
Date: February 19, 2004
Creator: Shlyaptseva, A S & Hansen, S B
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Lithium Surface Coatings for Improved Plasma Performance in NSTX

Description: NSTX high-power divertor plasma experiments have shown, for the first time, significant and frequent benefits from lithium coatings applied to plasma facing components. Lithium pellet injection on NSTX introduced lithium pellets with masses 1 to 5 mg via He discharges. Lithium coatings have also been applied with an oven that directed a collimated stream of lithium vapor toward the graphite tiles of the lower center stack and divertor. Lithium depositions from a few mg to 1 g have been applied … more
Date: February 19, 2008
Creator: Kugel, H. W.; Ahn, J.-W.; Allain, J. P.; Bell, R.; Boedo, J.; Bush, C. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Gyrokinetic Stability Studies of the Microtearing Mode in the National Spherical Torus Experiment H-mode

Description: Insight into plasma microturbulence and transport is being sought using linear simulations of drift waves on the National Spherical Torus Experiment (NSTX), following a study of drift wave modes on the Alcator C-Mod Tokamak. Microturbulence is likely generated by instabilities of drift waves, which cause transport of heat and particles. Understanding this transport is important because the containment of heat and particles is required for the achievement of practical nuclear fusion. Microtearin… more
Date: October 19, 2005
Creator: Baumgaertel J.A., Redi M.H., Budny R.V., Rewoldt G., Dorland W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Final Report LDRD 04-ERD-019 Development of absolute spectroscopic diagnostics for non-LTE plasmas

Description: This project sought to further our understanding of non-Local Thermodynamic Equilibrium (NLTE) processes by providing benchmark data to validate computational models. This has been a difficult regime to study in the laboratory, where experimental scales produce strong gradients while interpretation requires well-characterized uniform plasmas. It has also been a difficult regime to simulate, as evidenced by the large discrepancies in predictions of NLTE spectra for fixed plasma properties. Not s… more
Date: April 19, 2010
Creator: Scott, H. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Heatpulse Propagation Studies on DIII-D and TFTR

Description: Sawtooth phenomena have been studied on DIII-D and TFTR. In the experiments, with high power neutral beam injection the sawtooth characteristics were studied with fast electron temperature (ECE) and soft x-ray diagnostics. A strong ballistic electron heat pulse is found on DIII-D, stronger than was previously reported on TFTR. Evidence is presented in this paper that the ballistic effect is related to the sawtooth precursor. Fast, 2 msec interval, measurements on DIII-D were made of the ion tem… more
Date: April 19, 2000
Creator: Fredrickson, E.; Austin, M.E.; Groebner, R.; Manicham, J. & al, et
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Initial Studies of Core and Edge Transport of NSTX Plasmas

Description: Rapidly developing diagnostic, operational, and analysis capability is enabling the first detailed local physics studies to begin in high-beta plasmas of the National Spherical Torus Experiment (NSTX). These studies are motivated in part by energy confinement times in neutral-beam-heated discharges that are favorable with respect to predictions from the ITER-89P scaling expression. Analysis of heat fluxes based on profile measurements with neutral-beam injection (NBI) suggest that the ion therm… more
Date: September 19, 2001
Creator: Synakowski, E. J.; Bell, M. G.; Bell, R. E.; Bush, C. E.; Bourdelle, C.; Darrow, D. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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