Investigation of electron density and velocity distribution in high‐pressure discharges for excimer laser pumping using laser Thomson scattering

1991 ◽  
Vol 70 (1) ◽  
pp. 41-45 ◽  
Author(s):  
K. Uchino ◽  
Y. Kubo ◽  
K. Muraoka ◽  
T. Sakoda ◽  
H. Yamakoshi ◽  
...  
Keyword(s):  
High Pressure ◽  
Velocity Distribution ◽  
Electron Density ◽  
Excimer Laser ◽  
Thomson Scattering ◽  
Laser Pumping

The application of evolution strategies to disordered structures

1999 ◽  
Vol 32 (5) ◽  
pp. 902-910 ◽  
Author(s):  
Karsten Knorr ◽  
Fritz Mädler
Keyword(s):  
High Pressure ◽  
Maximum Entropy ◽  
Electron Density ◽  
Structural Model ◽  
Evolution Strategies ◽  
Qualitative Model ◽  
Density Distributions ◽  
Disordered Structures ◽  
Structure Factors ◽  
Complex Anions

Evolution strategies are applied to refine structural fragments, like molecules or complex anions, of orientationally disordered crystals. Optimal geometric embedding of the fragments into electron density distributions, resulting from maximum-entropy (ME) reconstructions, are performed. The evolution paradigm is found to be also applicable for the refinement against structure factors, for which the structural model is carefully selected from the ME densities. Suitably modified, the method is used successfully to compute reorientation pathways and to predict disordered high-pressure configurations in a non-classical qualitative model.

scholarly journals Density Irregularity of the Inner Corona determined from Simultaneous Measurements of the XUV and the K Coronal Brightness

1990 ◽  
Vol 142 ◽  
pp. 253-254
Author(s):  
M. Guhathakurta ◽  
G.J. Rottmann ◽  
R.R. Fisher ◽  
F.Q. Orrall
Keyword(s):  
Electron Density ◽  
White Light ◽  
Light Emission ◽  
Solar Limb ◽  
Position Angle ◽  
Thomson Scattering ◽  
White Light Emission ◽  
Kinetic Temperature ◽  
Data Sets ◽  
Chemical Abundance

In this paper we report preliminary results from a study of the inner corona based on the direct comparison of XUV resonance emission line λ174.53 FeX with that of the white-light emission from the K corona. The data sets were obtained 17718th of March, 1988, during a total solar eclipse of the sun and consists of co-spatial and co-temporal measurements of these two quantities as a function of position angle and height above the solar limb. The local emission of a coronal resonance line is proportional to the electron density squared, the chemical abundance, and the electron kinetic temperature, while the white-light emission (arising from Thomson scattering by electrons) depends directly on the electron density and the local radiation field. Taken together these measurements yield an estimate of the quantity where n is the electron density. This quantity, called “X the coronal irregularity factor” by C.W. Allen, is found to be >1.

scholarly journals Impact of electrical grounding conditions on plasma–liquid interactions using Thomson scattering on a pulsed argon jet

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Elmar Slikboer ◽  
James Walsh
Keyword(s):  
Electron Density ◽  
Applied Voltage ◽  
Voltage Pulse ◽  
Argon Plasma ◽  
Plasma Jet ◽  
Thomson Scattering ◽  
Electron Dynamics ◽  
Electron Density And Temperature ◽  
Argon Plasma Jet ◽  
Applied Voltage Pulse

AbstractThe interaction between an argon plasma jet excited using microsecond duration voltage pulses and a liquid target was examined using Thomson scattering to quantify the temporal evolution of the electron density and temperature. The electrical resistance between a liquid target and the electrical ground was varied from 1 to $$680\, \text {k}\Omega $$ 680 k Ω to mimic different conductivity liquids while the influence of the varying electrical properties on the electron dynamics within the plasma were examined. It was demonstrated that the interaction between the plasma jet and a liquid target grounded via a high resistance resulted in typical dielectric barrier discharge behaviour, with two discharge events per applied voltage pulse. Under such conditions, the electron density and temperature reached a peak of $$1\cdot 10^{15}\, \text {cm}^{-3}$$ 1 · 10 15 cm - 3 and 3.4 eV, respectively; with both rapidly decaying over several hundreds of nanoseconds. For liquid targets grounded via a low resistance, the jet behaviour transitioned to a DC-like discharge, with a single breakdown event being observed and sustained throughout the duration of each applied voltage pulse. Under such conditions, electron densities of $$2{-}3 \cdot 10^{15}\, \text {cm}^{-3}$$ 2 - 3 · 10 15 cm - 3 were detected for several microseconds. The results demonstrate that the electron dynamics in a pulsed argon plasma jet are extremely sensitive to the electrical characteristics of the target, which in the case of water, can evolve during exposure to the plasma.

scholarly journals Exploring charge density analysis in crystals at high pressure: data collection, data analysis and advanced modelling

2017 ◽  
Vol 73 (4) ◽  
pp. 584-597 ◽  
Author(s):  
Nicola Casati ◽  
Alessandro Genoni ◽  
Benjamin Meyer ◽  
Anna Krawczuk ◽  
Piero Macchi
Keyword(s):  
High Pressure ◽  
Density Distribution ◽  
Charge Density ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Theoretical Work ◽  
Specific Information ◽  
Collection Data ◽  
Modelling Techniques ◽  
Density Analysis

The possibility to determine electron-density distribution in crystals has been an enormous breakthrough, stimulated by a favourable combination of equipment for X-ray and neutron diffraction at low temperature, by the development of simplified, though accurate, electron-density models refined from the experimental data and by the progress in charge density analysis often in combination with theoretical work. Many years after the first successful charge density determination and analysis, scientists face new challenges, for example: (i) determination of the finer details of the electron-density distribution in the atomic cores, (ii) simultaneous refinement of electron charge and spin density or (iii) measuring crystals under perturbation. In this context, the possibility of obtaining experimental charge density at high pressure has recently been demonstrated [Casatiet al.(2016).Nat. Commun.7, 10901]. This paper reports on the necessities and pitfalls of this new challenge, focusing on the speciessyn-1,6:8,13-biscarbonyl[14]annulene. The experimental requirements, the expected data quality and data corrections are discussed in detail, including warnings about possible shortcomings. At the same time, new modelling techniques are proposed, which could enable specific information to be extracted, from the limited and less accurate observations, like the degree of localization of double bonds, which is fundamental to the scientific case under examination.

Sign in / Sign up

Export Citation Format

Share Document