scholarly journals High-precision measurement of velocity profiles in laser-created chlorine plasma

1995 ◽  
Vol 13 (4) ◽  
pp. 503-510 ◽  
Author(s):  
O. Renner ◽  
E. Krouský ◽  
T. Mißalla ◽  
E. Förster ◽  
G. Hölzer
Keyword(s):  
Spectral Lines ◽  
Plasma Parameters ◽  
High Precision Measurement ◽  
One Dimensional ◽  
Electron Temperature Gradient ◽  
Spatially Resolved ◽  
Doppler Shifts ◽  
Velocity Gradients ◽  
Marquardt Algorithm ◽  
The One

A vertical dispersion variant of the Johann spectrometer has been used to record the highresolution X-ray spectra of the chlorine He-like resonance line group emitted from lowradiance plasma. The emission profiles were measured at two observation angles and decomposed into single spectral lines by using a fit based on the Levenberg-Marquardt algorithm. The results of computerized analysis of the one-dimensional (1-D) spatially resolved spectra were used to evaluate the distribution of the main plasma parameters. The electron temperature gradient 7.5·104 eV cm-1 was computed by modeling the measured spectra with the collisional-radiative package RATION. The blowoff maximum velocities 4.2–6.1·107 cm s-1 and the velocity gradients 0.9–1.6·109 s-1 were determined from the Doppler shifts of individual spectral lines within their different spatial extent.

scholarly journals TODCOR: A Two-Dimensional Correlation of a Composite Spectrum to Derive the Radial Velocities of its Components

1992 ◽  
Vol 135 ◽  
pp. 164-166
Author(s):  
Tsevi Mazeh ◽  
Shay Zucker
Keyword(s):  
Radial Velocity ◽  
Cross Correlation ◽  
Radial Velocities ◽  
Two Dimensional ◽  
One Dimensional ◽  
Independent Variables ◽  
Doppler Shifts ◽  
Correlation Algorithm ◽  
Potential Difficulty ◽  
The One

Cross correlation is a frequently used technique to obtain the Doppler shifts of digitized celestial spectra. This method, suggested by Tonry & Davis (1979), cross correlates the observed spectrum against an assumed template, and obtains the stellar radial velocity by the location of the correlation maximum (Wyatt 1985). The technique finds the correct radial velocity even for extremely low S/N spectra.Spectra composed of two components present a potential difficulty to this technique. The cross correlation of these spectra usually displays a double peak which can not be resolved whenever the relative velocity of the two components is small. To overcome this difficulty, we developed TODCOR — a new TwO-Dimensional CORrelation algorithm which can simultaneously derive the Doppler shifts of the two components.TODCOR assumes that the observed spectrum is a combination of two known spectra with unknown shifts. Following the one-dimensional technique, the algorithm calculates the correlation of the observed spectrum against a set of combinations of two templates, with all possible shifts. The correlation, thus, is a two-dimensional function, whose two independent variables are the radial velocities of the two components. The location of the maximum of this function corresponds to the actual Doppler shifts of the two components.

Analysis of In-Flight Oxidation During Reactive Spray Atomization and Deposition Processing of Aluminum

1999 ◽  
Vol 122 (1) ◽  
pp. 126-133 ◽  
Author(s):  
J.-P. Delplanque ◽  
E. J. Lavernia ◽  
R. H. Rangel
Keyword(s):  
Volume Fraction ◽  
Oxide Thickness ◽  
Progression Rate ◽  
Spray Atomization ◽  
One Dimensional ◽  
Spatially Resolved ◽  
Dimensional Equation ◽  
The One ◽  
Solid Liquid Interface ◽  
Solid Liquid

This work defines a model to predict the characteristics of materials processed using reactive spray atomization and deposition. The materials considered are aluminum alloys while target dispersoids are primarily oxides. These may be obtained by the reaction of oxygen-containing atomization gas mixtures with molten alloy droplets. Droplet position and velocity histories are obtained from the numerical solution of the one-dimensional equation of motion. The energy equation inside the droplet is solved numerically using finite differences to predict the spatially resolved temperature field. The solid/liquid interface progression rate is estimated using a power law while an oxidation rate expression based on the Mott-Cabrera theory is used for the oxide thickness. Such a model should prove very valuable in determining the parameters controlling the volume fraction and the size distribution of the dispersoids for various systems. [S0022-1481(00)02901-7]

scholarly journals Height variation of magnetic field and plasma flows in isolated bright points

2019 ◽  
Vol 630 ◽  
pp. A139 ◽  
Author(s):  
Christoph Kuckein
Keyword(s):  
Magnetic Field ◽  
Imaging Spectroscopy ◽  
Spectral Lines ◽  
Plasma Flows ◽  
Doppler Shifts ◽  
Line Core ◽  
Resolution Element ◽  
Blue Wing ◽  
The One ◽  
The Magnetic Field

Aims. The expansion with height of the solar photospheric magnetic field and the plasma flows is investigated for three isolated bright points (BPs). Methods. The BPs were observed simultaneously with three different instruments attached to the 1.5 m GREGOR telescope: (1) filtergrams of Ca II H and blue continuum (4505 Å) with the HiFI, (2) imaging spectroscopy of the Na I D2 line at 5890 Å with the GFPI, and (3) slit spectropolarimetry in the 1 μm spectral range with the GRIS. Spectral-line inversions were carried out for the Si I 10827 Å Stokes profiles. Results. Bright points are identified in the Ca II H and blue continuum filtergrams. Moreover, they are also detected in the blue wing of the Na I D2 and Si I 10827 Å lines, as well as in the Ca I 10839 Å line-core images. We carried out two studies to validate the expansion of the magnetic field with height. On the one hand, we compare the photospheric Stokes V signals of two different spectral lines that are sensitive to different optical depths (Ca I vs. Si I). The area at which the Stokes V signal is significantly large is almost three times larger for the Si I line – sensitive to higher layers – than for the Ca I one. On the other hand, the inferred line-of-sight (LOS) magnetic fields at two optical depths (log τ = −1.0 vs. −2.5) from the Si I line reveal spatially broader fields in the higher layer, up to 51% more extensive in one of the BPs. The dynamics of BPs are tracked along the Na I D2 and Si I lines. The inferred flows from Na I D2 Doppler shifts are rather slow in BPs (≲1 km s−1). However, the Si I line shows intriguing Stokes profiles with important asymmetries. The analysis of these profiles unveils the presence of two components, a fast and a slow one, within the same resolution element. The faster one, with a smaller filling factor of ∼0.3, exhibits LOS velocities of about 6 km s−1. The slower component is slightly blueshifted. Conclusions. The present work provides observational evidence for the expansion of the magnetic field with height. Moreover, fast flows are likely present in BPs but are sometimes hidden because of observational limitations.

scholarly journals Nature of the solar dynamo at small scales

2012 ◽  
Vol 8 (S294) ◽  
pp. 119-130
Author(s):  
J. O. Stenflo
Keyword(s):  
Magnetic Flux ◽  
Spectral Lines ◽  
Magnetic Flux Density ◽  
Small Scale ◽  
Spatially Resolved ◽  
Small Scales ◽  
Depolarization Effect ◽  
The One ◽  
Time Invariant

AbstractIt is often claimed that there is not only one, but two different types of solar dynamos: the one that is responsible for the appearance of sunspots and the 11-yr cycle, frequently referred to as the “global dynamo”, and a statistically time-invariant dynamo, generally referred to as the “local dynamo”, which is supposed to be responsible for the ubiquitous magnetic structuring observed at small scales. Here we examine the relative contributions of these two qualitatively different dynamos to the small-scale magnetic flux, with the following conclusion: The local dynamo does not play a significant role at any of the spatially resolved scales, nearly all the small-scale flux, including the flux revealed by Hinode, is supplied by the global dynamo. This conclusion is reached by careful determination of the Sun's noise-corrected basal magnetic flux density while making use of a flux cancellation function determined from Hinode data. The only allowed range where there may be substantial or even dominating contributions from a local dynamo seems to be the scales below about 10 km, as suggested by observations of the Hanle depolarization effect in atomic spectral lines. To determine the fraction of the Hanle depolarization that may be due to the action of a local dynamo, a synoptic program is being initiated at IRSOL (Istituto Ricerche Solari Locarno).

scholarly journals High-resolution measurements of X-ray emission from dense quasi-1D plasma: Line merging and profile modification

1999 ◽  
Vol 17 (3) ◽  
pp. 365-375 ◽  
Author(s):  
O. RENNER ◽  
P. SONDHAUSS ◽  
O. PEYRUSSE ◽  
E. KROUSKÝ ◽  
R. RAMIS ◽  
...  
Keyword(s):  
Theoretical Data ◽  
Theoretical Models ◽  
Spectral Lines ◽  
Line Profiles ◽  
Plasma Parameters ◽  
X Ray ◽  
Profile Modification ◽  
Spatially Resolved ◽  
Plasma Line ◽  
Band Spectra

The precise measurements of the spectral line profiles near the short-wavelength limit of the Lyman series of Al are reported. The spatially resolved narrow-band spectra were attributed to macroscopic plasma parameters by using the results of 1D and 2D hydrodynamic plasma modeling. The gradual merging and broadening of the spectral lines Al Lyε–θ was compared to the synthetic spectra produced by atomic physics codes. The discrepancies between the experimental and theoretical data indicate the limits for applicability of standard theoretical models.

Exploring the Multidimensional Facets of Authoritarianism: Authoritarian Aggression and Social Dominance Orientation

2008 ◽  
Vol 67 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Stefano Passini
Keyword(s):  
Social Dominance ◽  
Factor Model ◽  
Three Dimensional ◽  
Social Dominance Orientation ◽  
Model Fit ◽  
Regression Analyses ◽  
One Dimensional ◽  
Confirmatory Factor ◽  
The One ◽  
Better Than

The relation between authoritarianism and social dominance orientation was analyzed, with authoritarianism measured using a three-dimensional scale. The implicit multidimensional structure (authoritarian submission, conventionalism, authoritarian aggression) of Altemeyer’s (1981, 1988) conceptualization of authoritarianism is inconsistent with its one-dimensional methodological operationalization. The dimensionality of authoritarianism was investigated using confirmatory factor analysis in a sample of 713 university students. As hypothesized, the three-factor model fit the data significantly better than the one-factor model. Regression analyses revealed that only authoritarian aggression was related to social dominance orientation. That is, only intolerance of deviance was related to high social dominance, whereas submissiveness was not.

Adiabatic large polarons in anisotropic molecular crystals

2011 ◽  
Vol 35 (1) ◽  
pp. 15-27
Author(s):  
Zoran Ivić ◽  
Željko Pržulj
Keyword(s):  
Energy Transfer ◽  
Effective Mass ◽  
Molecular Crystals ◽  
Single Chain ◽  
Proper Understanding ◽  
One Dimensional ◽  
Interchain Coupling ◽  
Large Polaron ◽  
The One

Adiabatic large polarons in anisotropic molecular crystals We study the large polaron whose motion is confined to a single chain in a system composed of the collection of parallel molecular chains embedded in threedimensional lattice. It is found that the interchain coupling has a significant impact on the large polaron characteristics. In particular, its radius is quite larger while its effective mass is considerably lighter than that estimated within the one-dimensional models. We believe that our findings should be taken into account for the proper understanding of the possible role of large polarons in the charge and energy transfer in quasi-one-dimensional substances.

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