11 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Electron Density"  
Results: 1 - 11
open access

Assessment of effects of neutrals on the power threshold for L to H transitions in DIII-D

Description: To assess the effect of edge neutrals on the low to high confinement transition threshold, a broad range of plasma discharges has been analyzed. From this analysis, the transition power divided by the density, at constant magnetic field, appears to be a function of a single parameter measuring the neutrals` effect, This parameter cannot be uniquely identified. For instance, it may be the radial decay length of the neutral profile or the charge exchange damping rate at about r/a {approx} 0.95. T… more
Date: September 1, 1997
Creator: Owen, L. W.; Carreras, B. A.; Maingi, R.; Mioduszewski, P. K.; Carlstrom, T. N. & Groebner, R. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Effects of ExB Velocity Shear and Magnetic Shear in the Formation of Core Transport Barriers in the DIII-D Tokamak

Description: Core transport barriers can be reliably formed in DIII-D by tailoring the evolution of the current density profile. This paper reports studies of the relative role of magnetic and ExB shear in creating core transport barriers in the DIII-D tokamak and considers the detailed dynamics of the barrier formation. The core barriers seen in DIII-D negative shear discharges form in a stepwise fashion during the initial current ramp. The reasons for the stepwise formation is not known; these steps do no… more
Date: December 31, 1997
Creator: Burrell, K. H.; Greenfield, C. M.; Lao, L. L.; Staebler, G. M.; Austin, M. E.; Rice, B. W. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Electron concentration and phase stability in NbCr2-based Laves phase alloys

Description: Phase stability in NbCr{sub 2}-based transition-metal Laves phases was studied, based on the data reported for binary X-Cr, Nb-X, and ternary Nb-Cr-X phase diagrams. It was shown that when the atomic size ratios are kept identical, the average electron concentration factor, e/a, is the dominating factor in controlling the phase stability of NbCr{sub 2}-based transition-metal Laves phases. The e/a ratios for different Laves polytypes were determined as followed: with e/a < 5.76, the C15 structur… more
Date: May 12, 1997
Creator: Zhu, J. H.; Liaw, P. K. & Liu, C. T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Analysis of D pellet injection experiments in the W7-AS Stellarator

Description: A centrifugal injector was used to inject deuterium pellets (with 3--5 x 10{sup 19} atoms) at approx. equal 600 m/s into current-less, nearly shear-less plasmas in the Wendelstein 7-AS (W7-AS) stellarator. The D pellet was injected horizontally at a location where the non-circular and non-axisymmetric plasma cross section is nearly triangular. Visible-light TV pictures usually showed the pellet as a single ablating mass in the plasma, although the pellet occasionally broke in two or splintered … more
Date: July 1, 1997
Creator: Lyon, J. F.; Baylor, L. R.; Baldzuhn, J.; Fiedler, S.; Hirsch, M.; Kuehner, G. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

A theoretical study of the electronic structure of Invar Fe*3Pt and related materials

Description: The Full Potential Linear Augmented Plane Wave (FPLAPW or FLAPW) method is used for a spin-polarized band calculation for ordered Fe{sub 3}Pt. As major purpose, the momentum distributions of the spin-polarized electrons are calculated and compared with results from a magnetic Compton scattering measurement. To get related information, the electronic behavior is also analyzed by examining the partial densities of states and the spatial electron distributions; the role of alloying effects is then… more
Date: January 10, 1997
Creator: Zuo, Zhiqi
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Fast ignitor coupling physics

Description: The Fast Ignitor is an alternate approach to ICF in which short pulse lasers are used to initiate burn at the surface of the compressed DT fuel. The aim is to avoid the need for careful central focusing of final shocks, and possibly to lower substantially the energy requirements for ignition. Ultimately, both goals may prove crucial to Science Based Stockpile Stewardship (SBSS). This will be the case should either emerging energetic needs, or funding difficulties render the presently planned ra… more
Date: October 1, 1997
Creator: Mason, R.J. & Tabak, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Relativistic charged particle in magnetic dipole-spherical geometry. III. Local three-dimensional states

Description: Following two previous papers, we examine single- and many-body states of relativistic charged particles in an intense, rotating magnetic dipole field. Single-body orbits are derived classically and semiclassically, and then applied to the many-body orbits are derived classically and semiclassically, and then applied to the many-body case via the Thomas-Fermi approximation. Examples of electrons in a realistic neutron star crust are considered with both fixed density profiles and constant Fermi… more
Date: July 1, 1997
Creator: Gopinath, K.S.; Kennedy, D.C. & Gelb, J.M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Measurements of slant and vertical TEC using data from FORTE and the TRACKER ray-tracing code

Description: In a previous informal report, the author described the FORTE satellite and the analysis techniques used to extract a slant TEC from measurements of the dispersion of a signal transmitted from and EMP generator at Los Alamos. In this report he reports on the use of a ray-tracing/ionospheric model code to deduce the vertical TEC to 800 km from the FORTE measurements.
Date: December 12, 1997
Creator: Massey, R.S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

The back transition and hysteresis effects in DIII-D

Description: The back transition from H-mode to L-mode has been studied on DIII-D as a part of the investigation of the L-H transition power threshold scaling. Based on a density-dependent scaling for the H-mode power threshold, ITER will require substantial hysteresis in this parameter to remain in H-mode as n{sub e} rises. Defining the hysteresis in terms of the ratio of sustaining to threshold power, P{sub HL}/P{sub LH} may need to be as small as 50% for ITER. Operation of DIII-D at injection powers slig… more
Date: September 1, 1997
Creator: Thomas, D. M.; Groebner, R. J.; Burrell, K. H.; Osborne, T. H. & Carlstrom, T. N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Informal report on measurements of slant TEC by FORTE

Description: Los Alamos National Laboratory`s Space and Atmospheric Sciences group is now operating the FORTE satellite, which has two sets of instruments: optical detectors and radio detectors. In this report the author describes work with one set of radio detectors that allow measurements of the total electron content (TEC) traversed by VHF radiation originating at an electromagnetic pulse (EMP) generator located at Los Alamos.
Date: November 21, 1997
Creator: Massey, R.S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Robustness of radiative mantle plasma power exhaust solutions for ITER

Description: The robustness of impurity-seeded radiative mantle solutions for ITER to uncertainties in several physics and operating parameters is examined. The results indicate that {approximately} 50--90% of the input power can be radiated from inside the separatrix with Ne, Ar and Kr injection, without significant detriment to the core power balance or collapse of the edge temperature profile, for a wide range of conditions on the impurity pinch velocity, edge temperature pedestal, and plasma density.
Date: December 31, 1997
Creator: Mandrekas, J.; Stacey, W.M. & Kelly, F.A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
Back to Top of Screen