Author: Dmitri NikitinePublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Optical and X-ray Diagnostics of the Formation of Laser Induced Plasmas in Gases and Vacuum
Author: Dmitri NikitineOptical and X-Ray Diagnostics of the Formation of Laser-Induced Plasmas in Gases and Vacuum
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
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.
Laser-Aided Diagnostics of Plasmas and Gases
Author: K MuraokaPublisher: CRC Press
ISBN: 1420034065
Category : Science
Languages : en
Pages : 307
Book Description
Updated and expanded from the original Japanese edition, Laser-Aided Diagnostics of Gases and Plasmas takes a unique approach in treating laser-aided diagnostics. The book unifies the subject by joining applications instead of describing each application as a totally separate system. In taking this approach, it highlights the relative strengths of
Fusion Energy Update
Author: Optical Diagnostics of Colliding Laser Produced Plasmas
Author: Colm FallonPublisher:
ISBN:
Category :
Languages : en
Pages : 141
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.
Laser Induced Plasmas & Optical Diagnostics
Author: Magesh ThiyagarajanPublisher:
ISBN: 9783846548745
Category :
Languages : en
Pages : 268
Book Description
Scientific and Technical Aerospace Reports
Author: Research in Molecular Laser Plasmas
Author: N. G. BasovPublisher: Springer Science & Business Media
ISBN: 1468416235
Category : Science
Languages : en
Pages : 122
Book Description
This volume reports investigations which form part of a major series of theoretical and experimental studies being carried out in the Laboratory of Low-Temperature Plasma Optics at the Lebedev Physics Institute in Moscow. The papers give the results of systematic investigations of the chemical composition and of the electrical and optical properties of discharge plasmas, and also of populations of laser levels. Reliable and detailed information is given on the dissociation of carbon dioxide gas in discharges; the nature of the velocity distribution function, average energies, and densities of electrons; and populations and vibrational temperatures of molecules in cw CO and CO lasers. The material in this volume is intended for specialists in quantum electronics and low temperature plasma diagnostics.
Nuclear Science Abstracts
Author: High-power Particle Beams (Beams '90) - Proceedings Of The 8th International Conference (In 2 Volumes)
Author: B N BreizmanPublisher: World Scientific
ISBN: 9814579211
Category :
Languages : en
Pages : 1406
Book Description
The Conference Proceedings include 11 invited papers and about 200 contributed papers on various scientific and technological aspects of high-power particle beams. The following subject areas are covered: Physics and Technology of High-Power Particle Beams, New Developments in Pulsed-Power Technology and High-Power Accelerators, Diagnostics in High-Power Particle Beam Experiments, High-Power Particle Beam Interactions with Matter, High-Power Particle Beams in Fusion Research, High-Density Z-Pinches, Laser Pumping and Microwave Generation by High-Power Particle Beams, Technical and Industrial Applications of Pulsed Power and High-Power Particle Beams.