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Momentum-energy transport from turbulence driven by parallel flow shear

Description: The low frequency E {times} B turbulence driven by the shear in the mass flow velocity parallel to the magnetic field is studied using the fluid theory in a slab configuration with magnetic shear. Ion temperature gradient effects are taken into account. The eigenfunctions of the linear instability are asymmetric about the mode rational surfaces. Quasilinear Reynolds stress induced by such asymmetric fluctuations produces momentum and energy transport across the magnetic field. Analytic formulas… more
Date: April 1, 1994
Creator: Dong, J. Q.; Horton, W.; Bengtson, R. D. & Li, G. X.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Isotope scaling and {eta}{sub i} mode with impurities in tokamak plasmas

Description: The ion temperature gradient driven instability, or {eta}{sub i} mode, is studied for discharges with hydrogen, deuterium or tritium in a toroidal magnetic configuration. Impurity effects on the mode and the instability which is driven by the presence of impurity ions (impurity modes) are studied as well. It is found that the maximum growth rate of the {eta}{sub i} mode scales as M{sup {minus}{1/2}} for pure hydrogen, deuterium or tritium discharges, where M is the mass of the working gas ion. … more
Date: April 1, 1994
Creator: Dong, J. Q.; Horton, W. & Dorland, W. D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Toroidal kinetic {eta}{sub i}-mode study in high temperature plasmas

Description: A new kinetic integral equation for the study of the ion temperature gradient driven mode in toroidal geometry is developed that includes the ion toroidal (curvature and magnetic gradient) drift motion {omega}{sub D}, the mode coupling from finite {kappa}{sub {parallel}} due to the toroidal feature of the sheared magnetic configuration. The integral equation allows the stability study for arbitrary {kappa}{sub {parallel}} {upsilon}{sub i}/({omega} {minus} {omega}{sub D}) and {kappa}{perpendicul… more
Date: November 1, 1991
Creator: Dong, J. Q., Horton, W. & Kim, J. Y.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Shear flow generation from the interaction of neoclassical and drift wave transport processes

Description: Self-consistent shear flow generation from the interaction of neoclassical and drift wave turbulence effects is investigated. The neoclassical poloidal flow damping is shown to compete with the flow generation driven by the divergence of the Reynolds stress. When there is no external driving force except for the free energy released from toroidal shear flow, the turbulent fluctuations occur as a transient pulse which takes the system along an equilibrium path to a relaxed state. External torque… more
Date: October 1, 1993
Creator: Su, X. N.; Yushmanov, P. N.; Dong, J. Q. & Horton, W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Toroidal kinetic. eta. sub i -mode study in high temperature plasmas

Description: A new kinetic integral equation for the study of the ion temperature gradient driven mode in toroidal geometry is developed that includes the ion toroidal (curvature and magnetic gradient) drift motion {omega}{sub D}, the mode coupling from finite {kappa}{sub {parallel}} due to the toroidal feature of the sheared magnetic configuration. The integral equation allows the stability study for arbitrary {kappa}{sub {parallel}} {upsilon}{sub i}/({omega} {minus} {omega}{sub D}) and {kappa}{perpendicul… more
Date: November 1, 1991
Creator: Dong, J. Q., Horton, W. & Kim, J. Y.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Development of a Universal Networked Timer at NSTX

Description: A new Timing and Synchronization System component, the Universal Networked Timer (UNT), is under development at the National Spherical Torus Experiment (NSTX). The UNT is a second-generation multifunction timing device that emulates the timing functionality and electrical interfaces originally provided by various CAMAC modules. Using Field Programmable Gate Array (FPGA) technology, each of the UNT's eight channels can be dynamically programmed to emulate a specific CAMAC module type. The timer … more
Date: September 23, 2005
Creator: Sichta, P.; Dong, J.; Lawson, J. E.; Oliaro, G. & Wertenbaker, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Capturing CO2 via reactions in nanopores.

Description: This one-year exploratory LDRD aims to provide fundamental understanding of the mechanism of CO2 scrubbing platforms that will reduce green house gas emission and mitigate the effect of climate change. The project builds on the team member's expertise developed in previous LDRD projects to study the capture or preferential retention of CO2 in nanoporous membranes and on metal oxide surfaces. We apply Density Functional Theory and ab initio molecular dynamics techniques to model the binding of C… more
Date: October 1, 2008
Creator: Leung, Kevin; Nenoff, Tina Maria; Criscenti, Louise Jacqueline; Tang, Z & Dong, J. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Overview of the NSTX Control System

Description: The National Spherical Torus Experiment (NSTX) is an innovative magnetic fusion device that was constructed by the Princeton Plasma Physics Laboratory (PPPL) in collaboration with the Oak Ridge National Laboratory, Columbia University, and the University of Washington at Seattle. Since achieving first plasma in 1999, the device has been used for fusion research through an international collaboration of more than twenty institutions. The NSTX is operated through a collection of control systems t… more
Date: December 3, 2001
Creator: Sichta, P.; Dong, J.; Oliaro, G. & Roney, P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Status of the Experimental Physics and Industrial Control System at NSTX

Description: The NSTX achieved first plasma in 1999. The Experimental Physics and Industrial Control System (EPICS) is used to provide data-integration services for monitoring and control of all NSTX engineering subsystems. EPICS is a set of software initially developed at U.S. DOE laboratories. It is currently used and maintained through a global collaboration of hundreds of scientists and engineers. This paper will relate some of our experiences using and supporting the EPICS software. Topics include reli… more
Date: January 28, 2002
Creator: Sichta, P. & Dong, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Control System for the NSTX Lithium Pellet Injector

Description: The Lithium Pellet Injector (LPI) is being developed for the National Spherical Torus Experiment (NSTX). The LPI will inject ''pellets'' of various composition into the plasma in order to study wall conditioning, edge impurity transport, liquid limiter simulations, and other areas of research. The control system for the NSTX LPI has incorporated widely used advanced technologies, such as LabVIEW and PCI bus I/O boards, to create a low-cost control system which is fully integrated into the NSTX … more
Date: October 27, 2003
Creator: Sichta, P.; Dong, J.; Gernhardt, R.; Gettelfinger, G. & Kugel, H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Lithium Pellet Injector Development for NSTX

Description: A pellet injector suitable for the injection of lithium and other low-Z pellets of varying mass into plasmas at precise velocities from 5 to 500 m/s is being developed for use on NSTX (National Spherical Torus Experiment). The ability to inject low-Z impurities will significantly expand NSTX experimental capability for a broad range of diagnostic and operational applications. The architecture employs a pellet-carrying cartridge propelled through a guide tube by deuterium gas. Abrupt deceleratio… more
Date: December 4, 2003
Creator: Gettelfinger, G.; Dong, J.; Gernhardt, R.; Kugel, H.; Sichta, P. & Timberlake, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Optical studies of the {beta}{double_prime}-(ET){sub 2}SF{sub 5}RSO{sub 3} R = CH{sub 2}CF{sub 2}, CHFCF{sub 2} and CHF system: Chemical tuning of the counterion

Description: The authors compare the polarized optical spectra of the organic metal {beta}{double_prime}-(ET){sub 2}SF{sub 5}CHFSO{sub 3} and the {beta}{double_prime}-ET{sub 2}SF{sub 5}CHFCF{sub 2}SO{sub 3} metal/insulator material with those of the first fully organic superconductor {beta}{double_prime}-ET{sub 2}SF{sub 5}CH{sub 2}SO{sub 3}. The small chemical modification of the counterion has a dramatic effect on the spectral and charge transport properties of these materials, and they discuss their elect… more
Date: July 24, 2000
Creator: Olejniczak, I.; Jones, B. R.; Dong, J.; Pigos, J. M.; Zhu, Z.; Garlach, A. D. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Structure of parallel-velocity-shear driven mode in toroidal plasmas

Description: It is shown that the Fourier-ballooning representation is appropriate for the study of short wavelength drift-like perturbation in toroidal plasmas with a parallel velocity shear (PVS). The radial structure of the mode driven by a PVS is investigated in a torus. The Reynolds stress created by PVS turbulence and proposed as one of the sources for a sheared poloidal plasma rotation is analyzed. It is demonstrated that a finite ion temperature may strongly enhance the Reynolds stress creation abil… more
Date: September 15, 1998
Creator: Dong, J.Q.; Xu, W.B.; Zhang, Y.Z. & Horton, W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Startup of the experimental physics industrial control system at NSTX

Description: The Experimental Physics Industrial Control System (EPICS) is a set of software which is being used as the basis of the National Spherical Torus Experiment's (NSTX) Process Control System, a major element of the NSTX's Central Instrumentation and Control System. EPICS is a result of a co-development effort started by several US Department of Energy National Laboratories. EPICS is actively supported through an international collaboration made up of government and industrial users. EPICS' good po… more
Date: December 17, 1999
Creator: Sichta, P. & Dong, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Studies of impurity mode and ITG mode in toroidal plasmas

Description: The impurity mode and {eta}{sub i} mode driven by impurity ions with outwardly peaked density profiles, just as it is at the boundary of tokamak plasmas, and the ion temperature gradient, respectively, are studied in high temperature toroidal plasmas. The gyrokinetic theory is applied and finite Larmor radius effects of both hydrogenic and impurity ions are included. It is found that the impurity mode is enhanced by the ion temperature gradient. In addition, the impurity ions with outwardly pea… more
Date: April 1, 1995
Creator: Dong, J.Q. & Horton, W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Studies of instability and transport in tokamak plasmas with very weak magnetic shear

Description: Ion temperature gradient (ITG or {eta}{sub i}) driven microinstabilities are studied, using kinetic theory, for tokamak plasmas with very weak (positive or negative) magnetic shear (VWS). The gradient of magnetic shear as well as the effects of parallel and perpendicular velocity shear (v{prime}{sub {parallel}} and v{prime}{sub E}) are included in the defining equations. Two eigenmodes: the double (D) and the global (G) are found to coexist. Parametric dependence of these instabilities, and of … more
Date: April 1, 1997
Creator: Dong, J. Q.; Zhang, Y. Z. & Mahajan, S. M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Shear flow effects on ion thermal transport in tokamaks

Description: From various laboratory and numerical experiments, there is clear evidence that under certain conditions the presence of sheared flows in a tokamak plasma can significantly reduce the ion thermal transport. In the presence of plasma fluctuations driven by the ion temperature gradient, the flows of energy and momentum parallel and perpendicular to the magnetic field are coupled with each other. This coupling manifests itself as significant off-diagonal coupling coefficients that give rise to new… more
Date: March 1, 1995
Creator: Tajima, T.; Horton, W.; Dong, J.Q. & Kishimoto, Y.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Study of micro-instabilities in toroidal plasmas with negative magnetic shear

Description: The micro-instabilities driven by a parallel velocity shear, and a temperature gradient of ions are studied in toroidal plasmas with negative magnetic shear. Both the fluid and the gyro-kinetic formulations are investigated. It is found that for a broad range of parameters, the linear growth rates of the modes are lower, and the threshold temperature gradient {eta}{sub icr} is higher for plasmas with negative magnetic shear compared to plasmas with positive magnetic shear of equal magnitude. Th… more
Date: March 1, 1996
Creator: Dong, J. Q.; Zhang, Y. Z.; Mahajan, S. M. & Guzdar, P. N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Optical Properties of {beta}''-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} : a novel superconductor with large discrete counterions.''

Description: The optical spectra of the organic superconductor {beta}{double_prime}-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} are measured over a wide spectral range (30-35000 cm{sup {minus}1}) as a function of temperature and polarization. The optical anisotropy is quite large compared with other ET-based organic superconductors, and the spectra are far from Drude-like over the full temperature range. A broad electronic band centered near 1000 cm{sup {minus}1} is observed at low temperature along the… more
Date: August 6, 1998
Creator: Dong, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The NSTX Central Instrumentation and Control System

Description: Earlier this year the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Laboratory achieved ''first plasma''. The Central Instrumentation and Control System was used to support plasma operations. Major elements of the system include the Process Control System, Plasma Control System, Network System, Data Acquisition System, and Synchronization System. This paper will focus on the Process Control System. Topics include the architecture, hardware interface, operator interf… more
Date: December 17, 1999
Creator: Oliaro, G.; Dong, J.; Tindall, K. & Sichta, P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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