Author: Magesh Thiyagarajan
Publisher:
ISBN: 9783846548745
Category :
Languages : en
Pages : 268

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Author: Dmitri Nikitine
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: Colm Fallon
Publisher:
ISBN:
Category :
Languages : en
Pages : 141

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Book Description
Recently prepulse techniques such as dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) have emerged as commonly used analytical techniques for qualitative and quantitative elemental investigations in various research fields and disciplines such as industrial, defense and medical applications. The performance of the DP-LIBS technique is strongly dependent on the choice of the experimental conditions. The key parameters that affect its performance are the target properties, laser wavelength, pulse duration, energy and spot-size, interpulse delay times, delay time of observations, ambient background gas pressure and geometrical setup of the optics. The DP-LIBS approach provides significant enhancement in the intensities of emission lines and their lifetimes, up to two orders of magnitude greater than conventional single pulse laser induced breakdown spectroscopy. The aim of the work presented here is to further advance prepulse techniques, as well as other methods to control species density, with a view to optimise emission in the visible wavelength range. In particular, a new technique involving reheating the stagnation layer formed at the collision front between two (or more) colliding plasmas is explored. Spatially and temporally resolved imaging and spectroscopy of the interaction region between two colliding plasmas are employed to demonstrate for the first time that pumping of an optimised stagnation layer significantly increases the intensity emission and duration of selected spectral lines. This technique offers the promise of tunable density and tunable energy (temperature) plasmas. It will potentially increase both the lifetimes and intensities of spectral lines in laser produced plasmas by creating relatively low density - high energy plasmas which can overcome the problem of flux loss due to opacity, which leads to the attenuation of discrete emission lines with a concomitant reduction in line contrast, signal-to-noise ratio (SNR) and signal-to-background ratio (SBR). The latter is a key parameter in determining the limit-of-detection (LOD) of the LIBS technique. Other applications of stagnation layers include the development of 'target fuel' for Extreme UltraViolet (EUV) and X-ray light sources with an especial emphasis on generating high repetition rate, preheated droplet-like targets that can compete with the current liquid drop targets. The latter suffer from clogging at the jet nozzle due to adiabatic expansion freezing. Also, unlike stagnation layers the basic parameters of the droplet fuel cannot be easily varied in the way that stagnation layers allow.

Author: Leon J. Radziemski
Publisher: CRC Press
ISBN: 1000147371
Category : Technology & Engineering
Languages : en
Pages : 474

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Book Description
This book discusses the physics of plasma initiation and reviews the features of dissipating, propagating plasmas. It deals with advances in diagnostics for high-energy, laser-fusion plasmas. The book reviews the basic physical processes, plasma characteristics of the "continuous optical discharge".

Author: C Arcoumanis
Publisher: CRC Press
ISBN: 1482263181
Category : Science
Languages : en
Pages : 266

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Book Description
From the automotive industry to blood flow monitoring, optical techniques and laser diagnostics are becoming integral parts in engineering and medical instrumentation. Written by leading global experts from industry, academic groups, and laboratories, this volume provides an international perspective on both existing applications and leading-edge r

Author: J. S. Cowpe
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Optical Emission Spectroscopy (OES) and Mass Spectrometry (MS) were employed in tandem for diagnostic studies of Nd:YAG (532 nm) laser induced plasma plumes. OES measurements of laser-induced silicon plasmas were performed through a range of ambient pressure regimes from atmospheric pressure down to ~10-4 mbar. The temporal evolution of the plasmas was characterised in terms of electron excitation temperature Te, ionisation temperature Ti, and electron density Ne. Electron densities were determined in the range 2.86? 1016 to 5.53? 1019 cm-3, electron temperatures were calculated in the range 8794 to 21229 K, and ionic species temperatures calculated in the range 13658 to 22551K. The requirements for OES analysis based on the assumption of Local Thermal Equilibrium (LTE) conditions existing within the plasmas are discussed. The plasma morphology and expansion dynamics with respect to pressure are described. Response Surface Methodology (RSM) was employed to optimise Laser-Induced Breakdown Spectroscopy (LIBS) analyses of silicon at atmospheric pressure and under vacuum conditions. Multivariate analysis software was used to design and analyse several multi-level, full factorial RSM experiments. A Quality Factor (QF) was conceived as the response parameter for the experiments, representing the quality of the LIBS spectrum captured for a given hardware configuration. A full parametric study of the LIBS hardware configuration was performed to determine the true response of the system; the outcome of which compares favourably with the results yielded from the RSM investigation. MS analyses of silicon and copper laser-induced plasma plumes were performed using a commercially available Residual Gas Analyser (RGA). The RGA sampling configuration was investigated in order to maximise neutral and ionic species detection from the laser-induced plasmas.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Die Wechselwirkung intensiver Laserstrahlung mit Festkörperoberflächen ruft oberhalb einer bestimmten Leistungsdichte eine Materialablation hervor und führt schließlich zur Herausbildung sogenannter laserinduzierter Plasmen. In diesem Zusammenhang wird in der Literatur über nichtlinear-optische Phänomene wie Selbstfokussierung und -Kanalisierung der Laserstrahlung, sowie Ausbildung beschleunigter Plasmafragmente berichtet. Gegenstand der vorliegenden Arbeit ist die Untersuchung der Form und der Dynamik solcher laserinduzierten Plasmen an verschiedenen metallischen Targets (Al, Cu, W, Ta) in verschiedenen Umgebungen (Luft, Vakuum, Argon) unter besonderer Berücksichtigung der Vor-pulskonfigurationen des Laserstrahles. Es ist festzustellen, daß sich nach der Einwirkung eines Vorpulses der Energie 1012 ... 1013 W/cm2 auf das metallische Target in Luft und Argon eine Stoßwelle ausbildet, die im Falle von Luft zu einem Plasmakanal der Elektronendichte um 102ð 1/cm3, im Falle von Argon zu mehreren pulsierenden Kanälen führt. In der Arbeitsregime des Lasers mit einigen Vorpulsen wird in Luft und Argon die Herausbildung einer entsprechenden Anzahl von Stoßwellen im Plasma beobachtet. Als Ergebnis der Einwirkung des nachfolgenden Hauptpulses auf die entstandene Stoßwellenstruktur formiert sich ein Plasmakanal. Infolge der komplexen hydrodynamischen Wechselwirkung zwischen dem Hauptpuls und den Stoßwellen, sowie der Einwirkung starker Magnetfelder, erfolgt ein Auswurf von Plasmafragmenten entgegengesetzt dem Vektor der einfallenden Laserstrahlung. Die Fragestellung nach Abhängigkeit der Anzahl der Plasmafragmente von der Anzahl der Stoßwellen und der Pulsenergie des Lasers wird in dieser Arbeit verfolgt. Im Vakuum rufen die Vorpulse dagegen lediglich eine flache Plasmawolke hervor, in der sich als Ergebnis der Einwirkung des Hauptlaserimpulses wiederum eine Stoßwelle bildet. Weiter wird die Herausbildung von Plasmakanälen beobachtet, die in einem stumpfen Winkel zum Vektor des e.

Author: Alice Delserieys
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Nikolaj Koroteev
Publisher: Springer-Verlag
ISBN: 3322964256
Category : Technology & Engineering
Languages : de
Pages : 206

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Book Description

Author: Jagdish P. Singh
Publisher: Elsevier
ISBN: 0128188308
Category : Science
Languages : en
Pages : 624

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Book Description
Laser-Induced Breakdown Spectroscopy, Second Edition, covers the basic principles and latest developments in instrumentation and applications of Laser Induced Breakdown Spectroscopy (LIBS). Written by active experts in the field, it serves as a useful resource for analytical chemists and spectroscopists, as well as graduate students and researchers engaged in the fields of combustion, environmental science, and planetary and space exploration. This fully revised second edition includes several new chapters on new LIBS techniques as well as several new applications, including flame and off-gas measurement, pharmaceutical samples, defense applications, carbon sequestration and site monitoring, handheld instruments, and more. LIBS has rapidly developed into a major analytical technology with the capability of detecting all chemical elements in a sample, of real- time response, and of close-contact or stand-off analysis of targets. It does not require any sample preparation, unlike conventional spectroscopic analytical techniques. Samples in the form of solids, liquids, gels, gases, plasmas, and biological materials (like teeth, leaves, or blood) can be studied with almost equal ease. This comprehensive reference introduces the topic to readers in a simple, direct, and accessible manner for easy comprehension and maximum utility. Covers even more applications of LIBS beyond the first edition, including combustion, soil physics, environment, and life sciences Includes new chapters on LIBS techniques that have emerged in the last several years, including Femtosecond LIBS and Molecular LIBS Provides inspiration for future developments in this rapidly growing field in the concluding chapter