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Full-Text Articles in Physics

On The Stark Broadening Parameters Of The Two Nii Spectral Lines Of The 3d-4f Transition, Vladimir Milosavljevic, Stevan Djenize Jun 1997

On The Stark Broadening Parameters Of The Two Nii Spectral Lines Of The 3d-4f Transition, Vladimir Milosavljevic, Stevan Djenize

Articles

Stark parameters (width and shift) of two singly ionized nitrogen spectral lines, that belong to 3d-4f transition have been measured in a linear pulsed, low pressure, arc discharge in the nitrogen-oxygen plasma at a 54000 K electron temperature and at a 2.8×10 23 m−3 electron density. The measured values have been compared to the existing experimental and calculated data


Optimization Of Plasmas For Recombination-Pumped Short-Wavelength Lasers, M. Murphy, C. Glasheen, F. A. Moscatelli, Thomas D. Donnelly Apr 1997

Optimization Of Plasmas For Recombination-Pumped Short-Wavelength Lasers, M. Murphy, C. Glasheen, F. A. Moscatelli, Thomas D. Donnelly

All HMC Faculty Publications and Research

We report on experiments investigating the optimization of laser-ablated plasmas which are used to produce recombination-pumped, short-wavelength lasers. We evaluate the density of electrons and neutral atoms in laser ablated lithium and carbon plasmas as a function of time and distance away from the ablated target surface. We use an interferometric technique which can reveal information about the temperature of the plasma electrons. We find that the cold electrons which result in gain in recombination-pumped lithium lasers on the Lyman-α transition are produced by the high-intensity pump pulse rather than the lower intensity ablating pulse.


Velocity–Space Drag And Diffusion In A Model, Two-Dimensional Plasma, Mark Anthony Reynolds, B.D. Fried, G.J. Morales Jan 1997

Velocity–Space Drag And Diffusion In A Model, Two-Dimensional Plasma, Mark Anthony Reynolds, B.D. Fried, G.J. Morales

Publications

The quasilinear fluctuation integral is calculated for a two-dimensional, unmagnetized plasma ~composed of charged rods!, and is expressed in terms of Fokker–Planck coefficients. It is found that in two dimensions, the enhanced fluctuations generated by fast electrons lead to anomalously large transport coefficients. In particular, the effect of a small population of fast electrons is only weakly dependent on their density. In three dimensions, the effect of fast electrons is masked by the dominant approximation, but higher-order terms describe processes similar to those in two dimensions, and these terms can become significant for weakly stable plasmas. The differences between two …


The Effect Of Three-Dimensional Freestream Disturbances On The Supersonic Flow Past A Wedge, Peter W. Duck, D. Glenn Lasseigne, M. Y. Hussaini Jan 1997

The Effect Of Three-Dimensional Freestream Disturbances On The Supersonic Flow Past A Wedge, Peter W. Duck, D. Glenn Lasseigne, M. Y. Hussaini

Mathematics & Statistics Faculty Publications

The interaction between a shock wave (attached to a wedge) and small amplitude, three-dimensional disturbances of a uniform, supersonic, freestream flow are investigated. The paper extends the two-dimensional study of Duck et al. [P W. Duck, D. G. Lasseigne, and M. Y. Hussaini, ''On the interaction between the shock wave attached to a wedge and freestream disturbances,'' Theor. Comput. Fluid Dyn. 7, 119 (1995) (also ICASE Report No. 93-61)] through the use of vector potentials, which render the problem tractable by the same techniques as in the two-dimensional case, in particular by expansion of the solution by means of …


Turbulence Modeling Of The Toroidal Wall Heat Load Due To Shear Flows Over Cavities In The Neutral Gas Blanket Divertor Regime, George Vahala, Linda L. Vahala, Joseph Morrison Jan 1997

Turbulence Modeling Of The Toroidal Wall Heat Load Due To Shear Flows Over Cavities In The Neutral Gas Blanket Divertor Regime, George Vahala, Linda L. Vahala, Joseph Morrison

Electrical & Computer Engineering Faculty Publications

Heat loads to the target plate in reactor tokamaks are estimated to be orders of magnitude higher than those that can be withstood by known materials. In regimes of plasma detachment, there is strong evidence that plasma recombination occurs near the divertor plate, leading to a cold neutral gas blanket. Because of the strong coupling between the plasma and the neutrals within the divertor region, there is significant neutral flows along field lines up to Mach 1.2 and Reynolds numbers over 1000. The effects of three dimensional (3D) neutral turbulence within the gas blanket on heat deposition to the toroidal …