scholarly journals Atomic physics for beam-target interactions

1984 ◽  
Vol 2 (4) ◽  
pp. 449-465 ◽  
Author(s):  
C. Deutsch
Keyword(s):  
Electron Number Density ◽  
Accurate Determination ◽  
Projectile Energy ◽  
Stark Broadening ◽  
Number Density ◽  
Compact Formulation ◽  
Electron Contribution ◽  
Hot Matter ◽  
Special Relevance

This survey is devoted to a few basic atomic problems associated with the stopping of nonrelativistic pointlike ions in dense and hot matter, and also to the Stark broadening diagnostics of the resulting beam-produced plasmas.First, we consider the free electron contribution, taken in the RPA approximation with an exact dynamic dielectric function, valid at any temperature. Therefore, we obtain stopping power and straggling for any projectile velocity. The temperature dependence is of special relevance for a projectile energy smaller than 5 MeV/a.m.u.Next, we revise the Barkas effect (Z3 corrections) through a novel and compact formulation, which is based on an analogy with electron impact broadening theory. It facilitates inclusion of the non hydrogenic and electronic structure of the target ions, in a more selective way. The results may increase the usual Z2-stopping by 15 to 30 per cent corrections.Then, we show how the Stark broadening diagnostics of the compressed D + T fuel, seeded with high Z species, arising from the surrounding envelopes, may provide accurate determination of the electron number density ne. In this connection, it should be appreciated that the relatively long compression times (≃ 20 nsec) suggested by the HIBALL numerical simulation allow for a nearly Local Thermodynamic Equilibrium (LTE) state in the target, with Te ≃ Ti. As a consequence, spectroscopic measurements are expected to be easier to implement in HIF targets, than in laser ones.A tentative proposal for the use of Stark broadening diagnostics of inflight excited and highly stripped ion projectiles is displayed in § 5.Experiments involving an HIB produced by a standard accelerator, and interacting with an independently produced coronal plasma are finally outlined.

Electron Number Density Studies in Moderate-Power Argon and Helium Microwave-Induced Plasmas

1987 ◽  
Vol 41 (5) ◽  
pp. 774-779 ◽  
Author(s):  
Peter G. Brown ◽  
Timothy J. Brotherton ◽  
John M. Workman ◽  
Joseph A. Caruso
Keyword(s):  
Electron Density ◽  
Electron Number Density ◽  
Degradation Products ◽  
Number Density ◽  
Electron Number ◽  
Microwave Induced Plasma ◽  
Central Plasma ◽  
Electron Contribution ◽  
Moderate Power ◽  
Observation Position

The electron number density of atmospheric-pressure argon and helium microwave-induced plasmas operating in the power regime of 100 to 450 W has been examined. The resulting data demonstrate a trend of increasing electron density, ne, for both the Ar and He microwave-induced plasmas as forward power is increased. An examination of ne vs. plasma observation position demonstrates a maximum in ne at the central plasma observation position for both plasmas. Further, spatial dependence of electron density appears to be more pronounced at high power levels. Nebulization of aqueous solutions containing varying concentrations of an easily ionizable element into the Ar microwave-induced plasma, MIP, demonstrates little if any effect on ne. Moreover, this observation can be explained by the fact that there is a far greater quantity of water than easily ionizable element being introduced into the plasma in a given time period. Thus the electron contribution resulting from water degradation products in the plasma far outweighs that from the relatively small amount of easily ionizable element present. This last point is further substantiated by an examination of the Ar MIP with and without solution nebulization.

scholarly journals Influence of the Distance between Focusing Lens and Target Surface on the Characteristics of Laser-excited Lead Plasma

2021 ◽  
pp. 4694-4701
Author(s):  
Qusay Adnan Abbas
Keyword(s):  
Electron Temperature ◽  
Pulse Laser ◽  
Electron Number Density ◽  
Laser Energy ◽  
Pulse Length ◽  
Target Surface ◽  
Spectral Lines ◽  
Stark Broadening ◽  
Number Density ◽  
Electron Number

      The present work investigated the effect of distance from target surface on the parameters of lead plasma excited by 1064nm Q-switched Nd:YAG laser. The excitation was conducted in air, at atmospheric pressure, with pulse length of 5 ns, and at different pulse laser energies. Electron temperature was calculated by Boltzmann plot method based on the PbI emission spectral lines (369.03 nm, 416.98 nm, 523.48, and 561.94 nm). The PbI lines were recorded at different distances from the target surface at laser pulse energies of 260 and 280 mJ. The emission intensity of plasma increased with increasing the lens-to-target distance. The results also detected an increase in electron temperature with increasing the distance between the focal lens and the surface of the target in all laser energies under study. In addition, the electron number density was determined by using the Stark broadening method. The data illustrated that the electron number density was increased with increasing the distance from target surface, reaching the maximum at a distance of 11 cm for all pulse laser energy levels under study.

scholarly journals Measurement of Laser-Induced Plasma: Stark Broadening Parameters of Pb(II) 2203.5 and 4386.5 Å Spectral Lines

2019 ◽  
Vol 73 (2) ◽  
pp. 133-151 ◽  
Author(s):  
Aurelia Alonso-Medina
Keyword(s):  
Yttrium Aluminum Garnet ◽  
Electron Number Density ◽  
Graphical Representation ◽  
Spectral Lines ◽  
Stark Broadening ◽  
Number Density ◽  
Electron Number ◽  
Breakdown Spectroscopy ◽  
Fundamental Wavelength ◽  
And Shifts

In this work, the Stark broadening parameters (widths and shifts) of the 2203.5 Å and 4386.5 Å Pb(II) spectral lines have been investigated and measured in laser-induced breakdown spectroscopy (LIBS), using a lead sample (99.999% purity). A Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser operating at its fundamental wavelength (10 640 Å), generating pulses of 290 mJ, 7 ns of duration, and a repeat frequency of 20 Hz, has been used for the ablation of said lead sample in vacuum and in a controlled argon atmosphere. A study to understand the expansion dynamics of the lead produced plasma was performed. The spectra have been obtained and measured at different time delays of the plasma evolution in the range of 0.15–9 μs, at which the temperature and electron number density are in the ranges of 28 200–8000 K and 1.3 × 1017 to 3 × 1015 cm−3, respectively. A graphical representation of the evolution of temperature and electron number density versus 0.3 to 6.5 μs delay from the laser pulse is presented. The important effect of the different environment where the plasma expands has been pointed out. Local thermodynamic equilibrium conditions have been checked. The obtained results of the Stark widths and shifts at the different temperatures and densities of electrons have been compared with the limited data available in the literature. This study aims to obtain more accurate values for these parameters and also to establish regularities and similarities for said parameters.

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