A theoretical treatment of the line-intensity jump in a decaying argon-arc plasma

Author(s):  
H. Shindo ◽  
S. Imazu ◽  
T. Inaba
2021 ◽  
Vol 923 (2) ◽  
pp. 188
Author(s):  
Dongwoo T. Chung ◽  
Patrick C. Breysse ◽  
Håvard T. Ihle ◽  
Hamsa Padmanabhan ◽  
Marta B. Silva ◽  
...  

Abstract Line-intensity mapping observations will find fluctuations of integrated line emission are attenuated by varying degrees at small scales due to the width of the line emission profiles. This attenuation may significantly impact estimates of astrophysical or cosmological quantities derived from measurements. We consider a theoretical treatment of the effect of line broadening on both the clustering and shot-noise components of the power spectrum of a generic line-intensity power spectrum using a halo model. We then consider possible simplifications to allow easier application in analysis, particularly in the context of inferences that require numerous, repeated, fast computations of model line-intensity signals across a large parameter space. For the CO Mapping Array Project and the CO(1–0) line-intensity field at z ∼ 3 serving as our primary case study, we expect a ∼10% attenuation of the spherically averaged power spectrum on average at relevant scales of k ≈ 0.2–0.3 Mpc−1 compared to ∼25% for the interferometric Millimetre-wave Intensity Mapping Experiment targeting shot noise from CO lines at z ∼ 1–5 at scales of k ≳ 1 Mpc−1. We also consider the nature and amplitude of errors introduced by simplified treatments of line broadening and find that while an approximation using a single effective velocity scale is sufficient for spherically averaged power spectra, a more careful treatment is necessary when considering other statistics such as higher multipoles of the anisotropic power spectrum or the voxel intensity distribution.


1981 ◽  
Vol 35 (5) ◽  
pp. 505-509 ◽  
Author(s):  
B. V. Pavlović ◽  
T. A. Mihailidi

The influence of external rotating magnetic field (RMF) on the electric arc plasma, and therefore the axial distributions of the spectral line intensities and the atomic concentrations of the investigated elements in the plasma, was studied. The axial distribution of the spectral line intensities has, in all of the investigated cases, such a shape that the intensity has a maximum close to the cathode in the case of a cathode excitation as well as in the case of an anode excitation. At that, there is a very significant influence of the RMF on the axial distributions of spectral line intensities of the investigated elements. The effect of the RMF on the arc, in the case of anode excitation, leads to an outstanding increase of spectral line intensities in the zones close to the cathode, whereas in the case of a cathode excitation, it leads to an expanding of the zones close to the cathode with relatively higher spectral line intensities. Determining the particle concentrations has shown that the shape of particle concentration axial distribution curves and spectral line intensity axial distribution curves of the same element is very similar. Thus, a conclusion is drawn about a great influence of the particle concentration axial distribution on the spectral line intensity axial distribution of the considered elements.


1981 ◽  
Vol 52 (2) ◽  
pp. 706-708 ◽  
Author(s):  
Haruo Shindo ◽  
Shingo Imazu ◽  
Tsuginori Inaba
Keyword(s):  
Time Lag ◽  

2005 ◽  
Vol 70 (8-9) ◽  
pp. 1033-1040 ◽  
Author(s):  
Miroslav Kuzmanovic ◽  
Jelena Savovic ◽  
Mirjana Pavlovic ◽  
Milovan Stoiljkovic ◽  
Ankica Antic-Jovanovic ◽  
...  

The current of a U-shaped argon stabilised DC arc was square modulated with a 40 Hz repetition frequency between 6 and 3 A. The delayed line intensity responses to the modulation of the arc current were investigated using calcium as a representative analyte. The intensities of both the atomic and ionic lines were monitored at different distances from the arc axis in the presence of various concentrations of the easily ionised element. Temporal evolutions were monitored on a millisecond time scale. It was found that the responses of the line intesity to the arc current change strongly depended on the observed radial position, especially in the vicinity of the arc axis. The obtained results showed a significant influence of even small amounts of the easily ionised element on the excitation and transport of the analyte and indicated a way of possibly improving the analytical capabilities of the excitation source.


1966 ◽  
Vol 24 ◽  
pp. 3-5
Author(s):  
W. W. Morgan

1. The definition of “normal” stars in spectral classification changes with time; at the time of the publication of theYerkes Spectral Atlasthe term “normal” was applied to stars whose spectra could be fitted smoothly into a two-dimensional array. Thus, at that time, weak-lined spectra (RR Lyrae and HD 140283) would have been considered peculiar. At the present time we would tend to classify such spectra as “normal”—in a more complicated classification scheme which would have a parameter varying with metallic-line intensity within a specific spectral subdivision.


Author(s):  
C. C. Ahn ◽  
D. H. Pearson ◽  
P. Rez ◽  
B. Fultz

Previous experimental measurements of the total white line intensities from L2,3 energy loss spectra of 3d transition metals reported a linear dependence of the white line intensity on 3d occupancy. These results are inconsistent, however, with behavior inferred from relativistic one electron Dirac-Fock calculations, which show an initial increase followed by a decrease of total white line intensity across the 3d series. This inconsistency with experimental data is especially puzzling in light of work by Thole, et al., which successfully calculates x-ray absorption spectra of the lanthanide M4,5 white lines by employing a less rigorous Hartree-Fock calculation with relativistic corrections based on the work of Cowan. When restricted to transitions allowed by dipole selection rules, the calculated spectra of the lanthanide M4,5 white lines show a decreasing intensity as a function of Z that was consistent with the available experimental data.Here we report the results of Dirac-Fock calculations of the L2,3 white lines of the 3d and 4d elements, and compare the results to the experimental work of Pearson et al. In a previous study, similar calculations helped to account for the non-statistical behavior of L3/L2 ratios of the 3d metals. We assumed that all metals had a single 4s electron. Because these calculations provide absolute transition probabilities, to compare the calculated white line intensities to the experimental data, we normalized the calculated intensities to the intensity of the continuum above the L3 edges. The continuum intensity was obtained by Hartree-Slater calculations, and the normalization factor for the white line intensities was the integrated intensity in an energy window of fixed width and position above the L3 edge of each element.


Author(s):  
Feng Tsai ◽  
J. M. Cowley

Reflection electron microscopy (REM) has been used to study surface defects such as surface steps, dislocations emerging on crystal surfaces, and surface reconstructions. However, only a few REM studies have been reported about the planar defects emerging on surfaces. The interaction of planar defects with surfaces may be of considerable practical importance but so far there seems to be only one relatively simple theoretical treatment of the REM contrast and very little experimental evidence to support its predications. Recently, intersections of both 90° and 180° ferroelectric domain boundaries with BaTiO3 crystal surfaces have been investigated by Tsai and Cowley with REM.The REM observations of several planar defects, such as stacking faults and domain boundaries have been continued by the present authors. All REM observations are performed on a JEM-2000FX transmission electron microscope. The sample preparations may be seen somewhere else. In REM, the incident electron beam strikes the surface of a crystal with a small glancing angle.


Sign in / Sign up

Export Citation Format

Share Document