Дисертації з теми "Laser plasma radiation"
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Gallacher, Jordan G. "Relativistic electrons and radiation from intense laser-plasma sources." Thesis, University of Strathclyde, 2010. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=15481.
Повний текст джерелаHansson, Björn. "Laser-Plasma Sources for Extreme-Ultraviolet Lithography." Doctoral thesis, KTH, Physics, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3677.
Повний текст джерелаThis thesis describes the development and characterizationof a liquidxenon- jet laser-plasma source forextreme-ultraviolet (EUV) radiation. It is shown how thissource may be suitable for production-scale EUV lithography(EUVL).
EUVL is one of the main candidates to succeeddeep-ultraviolet (DUV) lithography for large-scalemanufacturing of integrated circuits (IC). However, a majorobstacle towards the realization of EUVL is the currentunavailability of a source meeting the tough requirements onespecially power and cleanliness for operation in an EUVLstepper. The liquid-xenon-jet laser-plasma concept has keyadvantages that may make it suitable for EUVL since, e.g., itsplasma consists only of the inert noble gas xenon and since theliquidjet target technology enables plasma operation at largedistances from the source-hardware thereby reducing sputteringand to allowing for high-power operation.
At the beginning of the work described in this thesis, aspatial instability of the liquid-xenon-jet made stableoperation of a plasma at practical distances from the nozzleorifice dicult. However, an invention of a stabilization methodbased on applying localized heating to the tip of thejet-forming nozzle, resulted in stable jet operation. Thelongitudinal droplet stability of a liquid-droplet laser-plasmasource has also been investigated and improved.
Continuous improvements of especially the laser-power toEUV-radiation conversion eciency (CE) and the stability oflaser-plasma operation at large distances (several centimeter)from the nozzle are reported for the liquidxenon- jet laserplasma source. Furthermore, this source is characterizedregarding many parameters relevant for EUVL operationincluding, ion emission from the plasma and related sputteringof nearby components, source size and shape, therepetition-rate limit of the source and non-EUV emission fromthe plasma.
Although the main focus of the thesis has been thedevelopment and characterization of a liquid-xenon-jetlaser-plasma source for production-scale EUVL, the source mayalso be suitable for small field applications that benefit fromthe high potential brightness of the source. A method to scanthe plasma and thus minimize the photon losses whilemaintaining the object plane uniformity was developed.Furthermore, the first operation of a liquidtin- jet laserplasma is reported. Quantitative EUV flux measurements yieldrecord CE, but quantitative contamination measurements alsoindicate that a liquid-tin-jet laser plasma is not likely to beapplicable as a source for EUVL.
Debus, Alexander. "Brilliant radiation sources by laser-plasma accelerators and optical undulators." Forschungszentrum Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-91303.
Повний текст джерелаBellei, Claudio. "Measurements of optical radiation from high-intensity laser-plasma interactions." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/5372.
Повний текст джерелаCapdessus, Rémi. "Dynamique d'un plasma non collisionnel interagissant avec une impulsion laser ultra-intense." Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR15268/document.
Повний текст джерелаRésumé en anglais
Mishra, Rohini. "Isochoric heating of thin target by intense laser radiation." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1446449.
Повний текст джерелаKamtaprasad, Reuvani. "LASER PLASMA RADIATION STUDIES FOR DROPLET SOURCES IN THE EXTREME ULTRAVIOLET." Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2147.
Повний текст джерелаM.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE
Nomura, Yutaka. "Temporal characterization of harmonic radiation generated by intense laser-plasma interaction." Diss., kostenfrei, 2008. http://edoc.ub.uni-muenchen.de/8598/.
Повний текст джерелаCantono, Giada. "Relativistic Plasmonics for Ultra-Short Radiation Sources." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS353/document.
Повний текст джерелаPlasmonics studies how the electromagnetic radiation couples with the collective oscillations of the electrons within a medium. Surface plasmons (SPs), in particular, have a well-established role in the development of forefront photonic devices, as they allow for strong enhancement of the local EM field over sub-micrometric dimensions. Promoting the SP excitation to the high-field regime, where the electrons quiver at relativistic velocities, would open stimulating perspectives for the both the manipulation of ultra-intense laser light and the development of energetic, short radiation sources. Indeed, the excitation of resonant plasma modes is a possible strategy to efficiently deliver the energy of a high-power laser to a solid target, this being among the current challenges in the physics of highly-intense laser-matter interaction. Gathering these topics, this thesis demonstrates the opportunity of resonant surface plasmon excitation at ultra-high laser intensities by studying how such waves accelerate bunches of relativistic electrons along the target surface and how they enhance the generation of high-order harmonics of the laser frequency. Both these processes have been investigated with numerous experiments and extensive numerical simulations. Adopting a standard configuration from classical plasmonics, SPs are excited on solid, wavelength-scale grating targets. In their presence, both electron and harmonic emissions exhibit remarkable features that support the conception of practical applications. Putting aside some major technical and conceptual issues discouraging the applicability of plasmonic effects in the high-field regime, these results are expected to mark new promises to the exploration of Relativistic Plasmonics
D'Amico, Ciro. "Filamentation femtoseconde dans les milieux transparents passifs et amplificateurs, et étude de la filamentation comme source de radiation secondaire." Phd thesis, Ecole Polytechnique X, 2007. http://pastel.archives-ouvertes.fr/pastel-00003498.
Повний текст джерелаEstublier, Denis L. "Radiation emission and absorption in a hydrogen plasma of a laser engine." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42161.
Повний текст джерелаIn this work, we describe all the possible radiative processes occuring in a low temperature hydrogen plasma. Some of the fundamental concepts involving ionized gases and collision phenomena are presented, and a rigourous approach is used to show that classical mechanics is quite appropriate to our study.
As an application to a laser engine, we investigate the effects of the maximum temperature, the temperature gradient, the stretching of the plasma shape, the engine pressure, and the equivalent sphere radius, on the total emitted power, including absorbing mechanisms through the equation of radiative transfer.
Graphs related to spectral radiative exitances are included, and a complete set of graphs of the total power, permitting interpolations with respect to the above relevant paramaters, are also provided.
Master of Science
Cavallone, Marco. "Application of laser-plasma accelerated beams to high dose-rate radiation biology." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX063.
Повний текст джерелаCancer is the second leading cause of death globally, accounting for an estimated 9.6 million deaths, or one in six deaths, in 2018. Besides surgery and chemotherapy, radiotherapy is one of the major treatment modality. It consists in the use of ionising radiation to kill cancerous cells by depositing energy into the tumour and destroying the genetic material that controls how cells grow and divide. While both cancerous and healthy cells are damaged by radiation, the goal of radiotherapy is to increase the treatment selectivity by sparing as much as possible the healthy tissues. Optimisation of the selectivity reposes on several aspects, including spatial optimisation of the dose, precision of imaging techniques and dosimetry instruments, use of different radiations and temporal structures of dose delivery. In particular, the role of the dose-rate and the total irradiation time has not been extensively explored yet.Clinical accelerators typically deliver the dose with a dose rate around few Gy/min, leading to exposure times in the order of few minutes to deliver a therapeutic dose. While the effect of a reduction of the dose rate in the order of cGy/min is well known, the effect of high-dose rate, fast irradiation on living cells still need to be elucidated. Evidences of an effect of the high dose-rate on the biological response have been recently observed in many studies. In particular, in-vivo studies performed with electrons and photons produced by accelerator prototypes have shown that delivering the prescribed dose in a short exposure time (<500ms) and at a high dose-rate (>40Gy/s) increases the treatment selectivity by reducing the occurrence of secondary effects on healthy tissues compared to conventional treatments with the same total dose. Although theoretical explanations underpinning such phenomenon are still under discussion, the so-called FLASH protocol has been successfully tested with the first human patient in 2019, paving the way for further research in this domain. These important results point out the importance of the dose delivery modality on the treatment selectivity and the potential benefit that high dose-rate protocols may bring to clinics, asking for a deeper understanding of the physico-chemical and biological processes following fast dose deposition.In this scenario, Laser-Driven Particle (LDP) beams represent a unique tool to shed some light on the radiobiological response following high-dose rate irradiation. LDP sources are produced by focusing an ultra-short (~fs) and ultra-intense (1019 W/cm2) laser pulse on a solid or gaseous thin target (~μm), producing proton and electron bunches with duration of respectively a few picoseconds and a few femtoseconds. These characteristics allow the reach of extremely high peak dose-rate in the pulse of the order of ~109 Gy/s in comparison with conventional and FLASH treatment protocols. For this reason, LDP sources have been receiving great attention in the last decade, but their radiobiological effect is still debated and further systematic studies are required.This thesis discusses the potential of both Laser-Accelerated Protons (LAP) and Laser-Accelerated Electrons (LAE) produced by different types of commercially available high-power lasers systems. In particular, it presents experimental and theoretical studies carried out with three different types of LDP beams, i.e. Hz LAPs, single-shot LAPs and kHz LAEs, enabling different temporal modalities of dose delivery. The goal is to address some of the main issues related to the application of such sources to radiation biology and show viable solutions and irradiation protocols to perform systematic radiobiology studies. Such issues include accurate characterisation of the source, optimisation of the dose distribution at the biological target through the design of adapted transport beamlines and investigation of the behaviour of dosimetric instruments for high dose-rate dosimetry
Lanier, Steven t. "Dynamic Screening via Intense Laser Radiation and Its Effects on Bulk and Surface Plasma Dispersion Relations." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1011758/.
Повний текст джерелаBajlekov, Svetoslav. "Towards a free-electron laser driven by electrons from a laser-wakefield accelerator : simulations and bunch diagnostics." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:99f9f13a-d0c2-4dd8-a9a4-13926621c352.
Повний текст джерелаJu, Jinchuan. "Electron acceleration and betatron radiation driven by laser wakefield inside dielectric capillary tubes." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00861267.
Повний текст джерелаDunne, Anthony Michael. "Measurements of thermal and radiation energy transport in laser and soft X-ray heated targets." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336433.
Повний текст джерелаBourgeois, Pierre-Louis. "Modélisation de sources X générées par interaction laser-plasma en régime relativiste." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX073.
Повний текст джерелаWhen an ultra-short ultra-intense laser impulsion propagates through a low density gas jet, a plasma is created and a bunch of electrons can be accelerated through laser wakefield acceleration to Gev energies in only a few centimetres. Those accelerated electrons then emit what is called Betatron radiation: a highly focused X-ray source with extremely good spatial and temporal properties, which has a lot of possible applications including ultra-high resolution imaging.In this thesis, we investigate possible improvements to one of the main numerical tools used to simulate those phenomenons: the Particle-In-Cell codes (CALDER). We have especially studied a numerical artefact called the numerical Cherenkov radiation, that occurs when relativistic particles move at speeds aproaching the speed of light in a vaccuum.We show that this artefact has a negative impact on the behaviour of the accelerated electron beam, especially on its transverse motion, which leads to important errors on the betatron radiation calculated using PIC simulations.We then introduce a new approach to mitigate the impact of this numerical Cherenkov radiation on laser wakefield acceleration simulation with a simple modification of the electromagnetic field interpolation method used in PIC codes. The results obtained with this new technique show a meaningful improvement on the electron motion wich becomes close to the theoretically expected behaviour.We then explore other possible applications for this new technique, notably improving the modelization of betatron sources, vacuum laser acceleration or direct laser acceleration.The improvement of the computation of the particles transverse motion thanks to this new method leads to more accurate results but also enables us to study physical phenomenon with subtle effects that would otherwise be hidden among the numerical noise of the simulation
Gonoskov, Arkady. "Ultra-intense laser-plasma interaction for applied and fundamental physics." Doctoral thesis, Umeå universitet, Institutionen för fysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-84245.
Повний текст джерелаWilliamson, Thomas Patrick. "Expansion of laser-produced plasmas into vacuum and ambient gases." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391485.
Повний текст джерелаGhaith, Amin. "Towards compact and advanced Free Electron Laser." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS333/document.
Повний текст джерелаX-ray Free Electron Lasers (FEL) are nowadays unique intense coherent fs light sources used for multi-disciplinary investigations of matter. A new acceleration scheme such as Laser Plasma Accelerator (LPA) is now capable of producing an accelerating gradient of few GeV/cm far superior to that of conventional RF linacs. This PhD work has been conducted in the framework of R&D programs of the LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) project of advanced and compact Free Electron laser demonstrator with pilot user applications. It comprises a 400 MeV superconducting linac for studies of advanced FEL schemes, high repetition rate operation (10 kHz), multi-FEL lines, a Laser Wake Field Accelerator (LWFA) for its qualification by a FEL application. The FEL lines comports enables advanced seeding in the 40-4 nm spectral range using high gain harmonic generation (HGHG) and echo-enabled harmonic generation (EEHG) with compact short period high field cryogenic undulators. The study of compact devices suitable for compact FEL applications is thus examined. One first aspect concerns the reduction of the Free Electron Laser gain medium (electrons in undulator) where shortening of the period is on the expense of the magnetic field leading to an intensity reduction at high harmonics. Compact cryogenic permanent magnet based undulators (CPMUs), where the magnet performance is increased at cryogenic temperature making them suitable for compact applications, are studied. Three CPMUs of period 18 mm have been built: two are installed at SOLEIL storage ring and one at COXINEL experiment. A second part of the work is developed in the frame of the R&D programs is the COXINEL experiment with an aim at demonstrating FEL amplification using an LPA source. The line enables to manipulate the properties of the produced electron beams (as energy spread, divergence, induced dispersion due) before being used for light source applications. The electron beam generated is highly divergent and requires a good handling at an early stage with strong quadrupoles, to be installed immediately after the electron generation source. Hence, the development of the so-called QUAPEVAs, innovative permanent magnet quadrupoles with high tunable gradient, is presented. The QUAPEVAs are optimized with RADIA code and characterized with three magnetic measurements. High tunable gradient is achieved while maintaining a rather good magnetic center excursion that allowed for beam pointing alignment compensation at COXINEL, where the beam is well-focused with zero dispersion at any location along the line. The QUAPEVAs constitute original systems in the landscape of variable high gradient quadrupoles developed so far. A third part of the work concerns the observation of tunable monochromatic undulator radiation on the COXINEL line. The electron beam of energy of 170 MeV is transported and focused in a 2-m long CPMU with a period of 18 mm emitting radiation light at 200 nm. The spectral flux is characterized using a UV spectrometer and the angular flux is captured by a CCD camera. The wavelength is tuned with the undulator gap variation. The spatio-spectral moon shape type pattern of the undulator radiation provided an insight on the electron beam quality and its transport enabling the estimation of the electron beam parameters such as energy spread and divergence. The final aspect of the work is related to the comparison between the echo and high gain harmonic generation, in the frame of my participation to an experiment carried out at FERMI@ELETTRA. At FERMI, we have demonstrated a high gain lasing using EEHG at a wavelength of 5.9 nm where it showed a narrower spectra and better reproducibility compared to a two-stage HGHG. This PhD work constitutes a step forward towards advanced compact Free Electron Lasers
Koay, Chiew-Seng. "RADIATION STUDIES OF THE TIN-DOPED MICROSCOPIC DROPLET LASER PLASMA LIGHT SOURCE SPECIFIC TO EUV LITHOGRAPHY." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4268.
Повний текст джерелаPh.D.
Optics and Photonics
Optics
Belmouaddine, Hakim. "Physique, chimie et biologie de la filamentation d’impulsions laser femtosecondes en solutions aqueuses." Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/11220.
Повний текст джерелаAbstract : The present study is part in a new framework in radiobiology, introduced a decade ago: femtosecond laser-induced "cold" low density plasmas for the highly localized deposition of energy at sub-cellular scales in systems of biological interest. Since in aqueous solutions the action of such plasmas is equivalent to the deposition of a dose by ionizing radiation, plasma-mediated effects on solutes involve the radiation chemistry of water. This chemistry corresponds to the interaction of solutes with radical oxygen species as well as with secondary low energy electrons, produced by the plasma. Here, to better understand the radiation chemistry underlying the generation of low density plasmas in aqueous environments, we harnessed the multi-filamentation of powerful femtosecond laser pulses as a way to achieve a self-regulated production of spatially homogeneous low density plasma foci in water. The "cold" low density plasma micro-channels generated by the filamentation of the femtosecond laser pulses in aqueous solutions constitute a source of dense ionization. We studied the femtosecond laser filamentation in inorganic solutions to account for the radiation-assisted chemistry triggered by laser ionization in aqueous environment. We highlighted that the trivial optical control of the spatio-temporal distribution of light filaments in the irradiated sample resulted in the modulation of the corresponding radical chemistry. We concluded that these spatially and temporally resolved plasmas could be developed as a tool for the unprecedented control of chemistry under ionizing radiation. The addition of a spatial light modulator to control the filamentation process improves significantly our control on the spatio-temporal distribution of the laser-induced plasma channels. From a bundle of entangled random low density plasma channels, usually produced by the non-linear propagation of the powerful laser beam, we were able to obtain a programmable matrix of mono-filaments to achieve a more pervasive and homogeneous energy deposition. This method of irradiation allowed us to perform a detailed analysis to determine, quantify and compare the consequences of the laser irradiation with those of a conventional source of ionizing radiation (Gamma-Rays) on organic molecules (e.g. DNA) desolved in aqueous solutions. We showed that each filament behaves as an independent intense micro beam of ionizing radiation, that is capable of inducing complex DNA damage. We believe that a better understanding of the laser-induced plasma-mediated effects in aqueous solutions of biological interest will further the adoption of such laser-based ionisation sources, and that this unorthodox approach to radiation sciences will open new fields of investigation at the frontiers of radiation and laser-driven chemistry. Moreover, one of the principal conclusions of this thesis argues in favour of a shift of paradigm in radiation sciences, shuch that the consequences of ionising radiation would not only be considered for their injurious effects but also for the fine modulation of the functions of systems of biological interest. This sentiment paves the way for new emerging techniques and applications in biomedical fields.
Parr, David Michael. "A general theory of electronic parametric instability of relativistically intense laser light in plasma." Thesis, University of Essex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310043.
Повний текст джерелаAndré, Arnaud. "Etude numérique de l’interaction laser-plasma sous dense : de la propagation de l’impulsion au rayonnement émis par les électrons accélérés." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112098.
Повний текст джерелаAn intense and short laser pulse propagating through an under dense plasma creates a plasma wave in its wake. The huge electric fields generated by this wave are responsible for the acceleration of trapped electrons to high energies in a very short distance. A nonlinear acceleration regime, known as the bubble regime, is particularly exciting as it generates mono-energetic electron beams. Outstanding results have been obtained recently in this thematic. However, while the electron beam itself has been widely characterized, there is still a lack of information concerning the detail of the interaction process itself. During my thesis work, I contribute to bring responses to this problematic, by studying the information carried out by the light emitted during interaction using intensive numerical simulations.The first part of my thesis is the dedicated to the links existing between the properties of accelerated electrons and the radiation they emit. From its properties, we can deduce the direction of the electron beam at the end of the acceleration, as well as in some particular conditions inside the beam. It is also possible to observe variations of the interaction through radiations.The second part is dedicated to the pulse propagation study. The pulse shape and spectrum of the laser pulse can be modified during the interaction of the laser within the medium. We have studied the propagation of the pulse in Nitrogen and Argon for slightly relativistic intensity. We showed that in given conditions, the pulse spectrum can be shifted due to self-modulation, the generation of an electronic density gradient due to the gas ionization. We also studied the pulse propagation at higher intensity, in the bubble regime. We identified the origin of interaction variations, observed in the first part of the thesis through the emitted radiation study
Meyer, Christophe. "Experimental study of imprinting and hydrodynamic instabilities in laser and soft X-ray driven targets." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298814.
Повний текст джерелаGaillard, Romain Philippe. "The interaction of picosecond high intensity laser pulses with preformed plasmas and solid targets." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313744.
Повний текст джерелаMountford, Lorna Catherine. "High intensity laser interactions with sub-micron droplets." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369219.
Повний текст джерелаHadj-Bachir, Mokrane. "Laser à rayons X ultra-compact Raman XFEL." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0400/document.
Повний текст джерелаThe quest for a compact X-ray laser has long been a major objective of laser science. Several schemes using optical undulators are currently considered, in order to trigger the amplification of back scattered radiation, in Compton or inverse Compton regime. We have proposed a new concept of compact XFEL based on a combination between the physics of free electron lasers, of laser-plasma interactions, and of nonlinear optics. In this thesis, we study the necessary steps to trigger a X-ray laser during the interaction between a free relativistic electron bunch and an optical lattice created by the interference of two intense transverse laser pulses. For this purpose I developed a particular tracking code dubbed RELIC. RELIC allowed us to study the dynamics and injection process of a bunch of relativistic electrons into the optical lattice. Thanks to RELIC, we distinguished several interaction regimes depending on the relativistic electron bunch parameters, and on those of the optical lattice and its geometry. These studies are applied to the X ray amplification and supported by PIC simulations. RELIC also allowed us to model and analyze the first experiment conducted in october 2015 on the ”Salle Jaune” laser facility at LOA. This first experiment was very important to validate our theoretical models, and should prove to be an essential milestone for the development of a Raman X-ray free electron laser
Bergh, Magnus. "Interaction of Ultrashort X-ray Pulses with Material." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8274.
Повний текст джерелаSICCHIERI, LETICIA B. "Caracterização da lipoproteína de baixa densidade (LDL) por meios espectroscópicos." reponame:Repositório Institucional do IPEN, 2012. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10109.
Повний текст джерелаMade available in DSpace on 2014-10-09T14:08:02Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
Nuruzzaman, Shelly. "Study of parametric and hydrodynamic instabilities in laser produced plasmas." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391443.
Повний текст джерелаVinko, Sam M. "Creation and study of matter in extreme conditions by high-intensity free-electron laser radiation." Thesis, University of Oxford, 2011. https://ora.ox.ac.uk/objects/uuid:dccfa977-ebe9-4f1b-ab9d-270684fcbfca.
Повний текст джерелаDebus, Alexander [Verfasser], Roland [Akademischer Betreuer] Sauerbrey, and Jan-Michael [Akademischer Betreuer] Rost. "Brilliant radiation sources by laser-plasma accelerators and optical undulators / Alexander Debus. Gutachter: Roland Sauerbrey ; Jan-Michael Rost. Betreuer: Roland Sauerbrey." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://d-nb.info/1067732470/34.
Повний текст джерелаDesforges, Frédéric. "Injection induite par ionisation pour l’accélération laser-plasma dans des tubes capillaires diélectriques." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112118/document.
Повний текст джерелаThe interaction of a short (~ 10 - 100 fs) and ultra-intense (> 10^18 W/cm²) laser pulse with an underdense (< 10^19 cm^-3) plasma can accelerate, in a compact way, a fraction of the electrons of the plasma toward relativistic energies (~ 100 - 300MeV). This mechanism, called laser wakefield acceleration (LWFA), might have various applications such as the future ultra-high energy electron collider. Prior to this, additional investigations are needed to ensure, through LWFA, a stable and reproducible generation of electron bunches of high quality, i.e. low transverse and longitudinal emittances.In this thesis, the stability and the reproducibility of the electron self-injection were experimentally investigated in 8-20mm long, dielectric capillary tubes, with an internal radius of 76-89 µm, and filled with pure H2 at an electronic density of de (10 +/- 1.5)x10^18 cm^-3. Electron bunches were produced, at a rate of two shots per minute, with an accelerated charge above 40 MeV of (66+/-7) pC, a mean energy of (65+/-6) MeV, a divergence of (9+/-1) mrad, and a pointing fluctuation of 2.3 mrad. Three sources were identified for the fluctuations and drifts of the electron bunch properties: laser energy drift, change of the electron number density upramp, and laser pointing fluctuations. Restrictions on the operating regime were proposed in order to improve the stability and the reproducibility of the laser-plasma electron source.An alternative mechanism of electron injection into the plasma wave was also investigated: the ionization-induced injection. An experimental study demonstrated that electron bunches generated in a mixture of 99%H2 + 1%N2 have twice more accelerated charge than in the case of pure H2. Moreover, the earlier onset of electron injection was observed for the mixture 99%H2 + 1%N2, indicating that the first electrons were trapped under the mechanism of ionization-induced injection. Particle-In-Cell simulations performed with the code WARP confirm the experimental results and suggest that the self-injection was inhibited by the ionization-induced injection
Lobet, Mathieu. "Effets radiatifs et d'électrodynamique quantique dans l'interaction laser-matière ultra-relativiste." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0361/document.
Повний текст джерелаThis PhD thesis is concerned with the regime of extreme-intensity laser-matter interaction that should be accessed on upcoming multi-petawatt facilities (e.g. CILEX-Apollon, ELI, IZEST). At intensities IL > 1022 Wcm-2, the relativistic dynamics of the laser-driven electrons becomes significantly modified by high-energy radiation emission through nonlinear inverse Compton scattering. For IL > 1023 Wcm-2, the emitted-ray photons can, in turn, interact with the laser field and decay into electron-positron pairs via the nonlinear Breit-Wheeler process. These quantum electrodynamic processes, which until recently could only be explored on large-scale particle accelerators, can greatly alter the "standard" mechanisms of laser-plasma interaction, and therefore its overall energy budget. In order to model their intricate interplay with the laser-induced plasma processes, they have been implemented within the particle-in-cell code calder developed at CEA. In a first part, we study these QED processes in the interaction of an ultra-intense laser with a micrometric overdense target. It is found that the laser-to--ray energy conversion efficiency can by far exceed 10% for intensities IL > 1023 Wcm-2, while copious pair production (through pair cascading) kicks in for IL > 1024 Wcm-2. In a second part, we consider positron generation in the collision between a GeV electron bunch issued from a laser-wake eld accelerator and a counterpropagating laser pulse. In a third part, we analyze a prospective scheme of astrophysical interest, consisting in the collision between two dense pair plasmas produced from solid targets irradiated at 1024 Wcm-2 showing a fast-growing magnetic lamentation instability amplified by intense synchrotron emission
Morrison, John T. "Selective Deuteron Acceleration using Target Normal Sheath Acceleration." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1365523293.
Повний текст джерелаCarrier-Vallieres, Simon. "Towards reliable, intense and high repetition-rate laser-driven ion beamlines." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0224.
Повний текст джерелаParticle accelerators attract a lot of attention in the scientific and non-scientific community as a result of their wide applicability in fields ranging from fundamental sciences, medicine to industrial applications. This doctoral work stands at the forefront of laser-based ion accelerators, and pushes forward their development to make them more competitive ion sources compared to conventional particle accelerators. For achieving higher competitiveness, laser-driven ion sources must be compact, cost-effective, reliable, intense and operated at high repetition-rates, which all together yield ion beam characteristics that cannot be realistically matched by any other kind of ion accelerator. To do so, the general effort of this doctoral work tackled three different aspects of laser-based ion acceleration, namely precise target alignment, improved targetry using nanostructures and the development of efficient particle diagnostics. The endeavor required to perform equivalent amounts of numerical work, through simulations using High Performance Computing, as well as experimental work, by implementing a cutting-edge ion beamline at the Advanced Laser Light Source (ALLS) 100 TW facility and to carry out several experimental campaigns abroad.The first part of the work aims at improving the reliability of ion beams through the precise positioning of solid targets used in laser-driven ion acceleration. For this purpose, a Target Positioning Interferometer (TPI) that reaches subwavelength positioning precision was developed. The TPI’s novel design is a modified Michelson interferometer that incorporates an aspherical converging lens in the target arm to transform it from a relative to an absolute positioning device, having a single unambiguity point in space. The high positioning accuracy is also achieved by a numerical fringe analysis algorithm that maximizes the extraction of signals with high signal-to-noise ratio, in an optimized timeframe. The development of a fast algorithm is crucial to make the TPI a viable solution for its implementation in a laser-based ion accelerator.The second part of the work is focused on enhancing the acceleration mechanism to generate higher ion numbers and kinetic energies, leading to more intense ion bunches. The solid targets used are typically flat metallic targets which allow for less than 10% of laser energy absorption, thereby limiting the laser-to-ion conversion efficiency to a few percent. A way to increase this conversion efficiency is by using target surface nanostructuration to trap the incoming laser pulse, ultimately leading to a greater energy transfer to the ions. We have shown, both theoretically and experimentally, that a careful optimization of a nanostructure’s geometrical parameters, in particular for nanospheres and nanowires, leads to multiple-fold enhancements of ion numbers and kinetic energies, compared to the use of the same laser pulse incident on flat targets of the same material.The final part of the work is dedicated to the development of efficient particle diagnostics suitable for being implemented on high repetition-rate laser-based ion beamlines. We first performed the absolute number calibration of the new EBT-XD type of radiochromic films (RCF). The EBT-XD exhibit larger dose detection range and higher minimum energy threshold compared to their EBT3 counterpart, hence more suitable for intense ion beamlines. A severe response quenching was remarked when the Bragg peak of the measured particle falls directly within the active layer of the RCF, causing significant particle number misestimation errors. Finally, we have developed a Thomson Parabola (TP) and Time-of-Flight cross-calibrated set of particle diagnostics that were incorporated on the ALLS 100 TW ion beamline. The TP spectrometer uses a microchannel plate (MCP) detector that was calibrated from single proton impacts to reconstruct the response function of the MCP detection system
OLIVEIRA, EDUARDO S. "Ablação seletiva de um filme de nitreto de titânio em substrato de carboneto de tungstênio utilizando laser de pulsos ultracurtos." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27976.
Повний текст джерелаMade available in DSpace on 2017-11-09T11:36:10Z (GMT). No. of bitstreams: 0
Revestimentos superficiais são aplicados à muitas ferramentas de usinagem na indústria metalúrgica com o intuito de melhorar a eficiência de corte e aumentar sua vida útil. Neste trabalho foram realizados testes para remoção do recobrimento de nitreto de titânio alumínio (TiAlN) em pastilhas de carboneto de tungstênio (WC-Co), utilizando um feixe laser de pulsos ultracurtos. Após a determinação dos limiares de dano do filme e do substrato foram ablacionados na superfície do recobrimento, traços utilizando duas condições de ablação. Inicialmente operou-se no regime de baixa fluência do filme, e posteriormente no regime de baixa fluência do substrato, muito abaixo do limiar do filme, aplicando-se alta sobreposição de pulsos. Um sistema de espectroscopia de emissão atômica induzida por laser (LIBS) foi montado para monitoramento dos materiais presentes no plasma gerado pelo laser, porém o sistema não apresentou sensibilidade suficiente para leitura da baixa intensidade do plasma proveniente do processo e não foi utilizado. Após a análise dos traços por microscopia eletrônica, perfilometria óptica e espectroscopia por fluorescência de Raios-X, não foi possível determinar um processo seguro para realizar a remoção seletiva do filme em questão, porém, devido aos dados obtidos e observações dos resultados em alguns traços, novas possibilidades foram levantadas, abrindo a discussão para a realização de trabalhos futuros.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
Vauzour, Benjamin. "Étude expérimentale du transport d'électrons rapides dans le cadre de l'allumage rapide pour la fusion inertielle." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14496/document.
Повний текст джерелаThe framework of this PhD thesis is the validation of the fast ignition scheme for the nuclear fusion by inertial confinement. It consists in the experimental study of the various processes involved in fast electron beams propagation, produced by intense laser pulses (10^{19} W.cm-2), through dense matter either solid or compressed. In this work we present the results of three experiments carried out on different laser facilities in order to generate fast electron beams in various conditions and study their propagation in different states of matter, from the cold solid to the warm and dense plasma.The first experiment was performed with a high intensity contrast on the UHI100 laser facility (CEA Saclay). The study of fast electron energy deposition inside thin aluminium targets highlights a strong target heating at shallow depths, where the collectivs effects are predominant, thus producing a steep temperature profile between front (300eV) and rear (20eV) sides over 20µm thickness. A numerical simulation of the experiment shows that this temperature gradient induces the formation of a shock wave, breaking through the rear side of the target and thus leading to increase the thermal emission. The experimental chronometry of the shock breakthrough allowed validating the model of the collective transport of electrons.Two other experiments were dedicated to the study of fast electron beam propagation inside compressed targets. In the first experiment on the LULI2000 laser facility, the plane compression geometry allowed to precisely dissociate the energy losses due to resistive effects from those due to the collisional ones. By comparing our experimental results with simulations, we observed a significative increase of the fast electron beam energy losses with the compression and the target heating to temperatures close to the Fermi temperature. The second experiment, performed in a cylindrical geometry, demonstrated a fast electron beam guiding phenomenon due to self-generated magnetic fields in presence of sharp radial resistivity gradients. Furthermore, in the temperature and density conditions achieved here, the increase of collisional energy losses with density is compensated by the decreasing resistive energy losses due to the transition of the conductivity into the high-temperatures Spitzer regime
Michel, Thibault. "Étude des chocs radiatifs dans le cadre de l'astrophysique de laboratoire." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX095.
Повний текст джерелаThe development of lasers for several decades now allows to concentrate a macroscopic quantity of energy (around ;1 kJ) in a small volume (a few mm3) and over a short duration (around 1 ns). This defines the High Energy Densities (HED) regime, that can be found in planet's core or inside stellar systems. Laboratory Astrophysics is the frame of this thesis, which consists of performing experiments in the laboratory with high-energy lasers. Coupled with scaling laws, experiments results can be used to model dedicated astrophysical phenomena. The experimental parameters that are measured can be extended to the reproduced astrophysical system. During this thesis, we focused on a specific type of phenomenon: radiative shocks. These are present for example during supernova explosions, around molecular clouds, or in accretion disks.We first study the experimental aspect of the radiative shock generated by high energy lasers, especially at the GEKKO laser facility in Osaka (Japan). In particular, we determine the criteria that must be considered to qualify a shock as a "radiative" shock, then we study the experimental constraints that make it possible to generate it, which requires an important work of numerical simulation.Afterwards, we expose different aspects of the interaction between a radiative shock and a solid obstacle, reproducing the ablation of a molecular cloud by massive stars in its neighbouhood. We present theoretical, numerical and experimental aspects.Another effect that has been found experimentally, then explained analytically and numerically, is the deceleration of a shock when radiative effects are significant. This leads to instabilities developments, like in SN1987A supernova circumstellar medium. The model developed gives a possible explanation on the evolution of hotspots observed in the circumstellar medium.Finally, in order to study these effects experimentally for a shock with higher radiative effects, we present in this thesis the design of a Laser MegaJoule (LMJ) experiment that will take place in 2020.Many perspectives are given at the end of the manuscript, giving some experimental development but also theoretical improvements concerning the classification of radiative shocks
Delahaye, Frédéric. "Fibre microstructurée à cœur plasma pour la génération de radiations ultraviolettes." Thesis, Limoges, 2019. http://aurore.unilim.fr/theses/nxfile/default/eb8bad31-ba1b-4347-97cc-ea597d1238fb/blobholder:0/2019LIMO0096.pdf.
Повний текст джерелаThe generation of microwave micro-plasmas by non-intrusive excitation inside hollow-core photonic crystal fibers (HC-PCF), allowed the emergence of a new platform emitting in the ultraviolet range. Based on the surface wave generation, the observed plasma columns are of 50 mm confined to a micrometric scale. Despite a plasma temperature close to the transforming the microstructured silicat this one is not affected, preserved by a particular plasma dynamics. This work includes a study on the development of inhibited coupling fiber with an expended core (i.e., core diameter> 200 μm) with short wavelength transmission bands. These transmission bands make itpossible to guide the plasma fluorescence in the ultraviolet optimized by ternary gas mixture of argon, oxygen and nitrogen. These two demonstrations are at the origin of the realization of a tunable ultraviolet plasma source with more than 20 lines ranging from 450 nm to 200 nm. With optical outputs of more than 1 μW at 314 nm and 337 nm. A final experimental study on the possibility to use the plasma as an optical amplifier medium opens the way for the realization in the near future of portable ultraviolet laser sources
Chaulagain, Uddhab Prasad. "Radiative shocks : experiments, modelling and links to astrophysics." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066734.
Повний текст джерелаRadiative shocks are strong shocks which are characterized by a plasma at high temperatures emitting an important fraction of its energy as radiation. Radiative shocks are found in many astrophysical systems, including stellar accretion shocks, supernovae remnants, jet driven shocks, etc. Recently, radiative shocks have also been produced experimentally using high energy lasers. Thus opening the way to laboratory astrophysics studies of these universal phenomena.In this thesis we discuss the results of an experiment performed on the Prague Asterix Laser System facility. Shocks are generated by focusing the PALS Infrared laser beam on millimetre-scale targets filled with xenon gas at low pressure. The shock that is generated then propagates in the gas with a sufficiently high velocity such that the shock is in a radiative flux dominated regime. We used different diagnostics to characterize these shocks. The two main ones include a radiography of the whole shock structure using sub-nanosecond Zn X-ray laser at 21.2 nm, which is able to penetrate the dense post-shock layer, and a space-and-time resolved plasma self-emission using high speed diodes.The experimental results show, for the first time, an unambiguous shock structure which includes both the post-shock and the precursor, and we also obtained multiple shock velocity measurements from the different diagnostics. The experimental results are compared to simulations, and show good agreement with the numerical results
Kerr, Fraser Martin. "Line radiation effects in laser-produced and astrophysical plasmas." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422662.
Повний текст джерелаEvans, A. M. "Studies of plasmas produced by high power laser radiation." Thesis, Swansea University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636936.
Повний текст джерелаBeaucourt-Jacquet, Céline. "Étude expérimentale du guidage du faisceau d’électrons dans le cadre de l’allumage rapide de cibles de fusion." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14741/document.
Повний текст джерелаThe work presented in this thesis is realised in the framework of the fast ignition of inertial confinement fusion for energy production. In this scheme the compression and the ignition phases are decoupled. During the second phase, the electron beam must cross over 300 µm in the dense fuel to deposit its energy in the dense core and ignite the fusion reactions.The major problem of the scheme is related to the divergence of the electron beam while it crosses the dense matter. Among the different propositions to inhibit the electron divergence we consider here the schemes without cone that are based on the effect of magnetic collimation. In particular, A.P.L. Robinson and his co-authors [Phys. Rev. Lett. 100, 025002, 2008] suggested a simple way to control the electron beam divergence by using a sequence of two laser pulses. The first one creates a magnetic background favourable for the confinement of the second electron beam resulting from the second interaction. The validation of this scheme is the major goal of this thesis.We present the results of experimental sudies and numerical modeling of the electron beam guiding with help of two consequent laser pulses. The experiment was performed on the Vulcan facility at the Rutherford Appleton Laboratory at Didcot in UK, based on the proposal submitted by an international group of scientists in the framework of the European project for inertial fusion energy HiPER. This experiment allowed us to define a combination of laser and target parameters where the electron beam guiding takes place. The analysis of experimental data and numerical modelling is realised with the hydrodynamic code CHIC coupled to the charged particules transport module M1. The interpretation of the experimental results allowed us to explain the experimental data and the physical basis of guiding and to define the magnetic conditionflavourable to the electron beam guidance
Marcerou, Pascal. "Modélisation numérique bidimensionnelle du transfert radiatif dans un plasma créé par interaction laser-matière." Toulouse 3, 1992. http://www.theses.fr/1992TOU30059.
Повний текст джерелаDemir, Arif. "Spectroscopy of X-ray laser media." Thesis, University of Essex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361175.
Повний текст джерелаLe, Quang Huy Damien. "Spectroscopic measurements of sub-and supersonic plasma flows for the investigation of atmospheric re-entry shock layer radiation." Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22462/document.
Повний текст джерелаDuring planetary atmospheric entries, thermochemical non-equilibrium processes in the shock layer limit the reliability of aerothermal environment prediction. To improve prediction accuracy, non-equilibrium kinetic models are being developed. These models are experimentally assessed through the comparison with well characterized non-equilibrium experiments. For this purpose, the present work is dedicated to the thermodynamic characterization of non-equilibrium in high enthalpy reactive flows. Conversely to common studies that employ short duration facilities to investigate shock layer kinetics, we will assess the possibility of producing significant departure from equilibrium using radio-frequency and microwave stationary plasma flows, including supersonic plasma flows where vibrational non-equilibrium is strongly expected. Suitable spectroscopic diagnostics have been applied allowing future comparisons to be made between the microscopic description of the experiments and theoretical non-equilibrium models
D'Etat, Brigitte. "Etude theorique et experimentale des series spectrales emises par un plasma de laser." Paris 6, 1987. http://www.theses.fr/1987PA066363.
Повний текст джерелаLacroix, David. "Etude spectroscopique des plasmas de soudage laser : application au transfert d'énergie." Nancy 1, 1997. http://docnum.univ-lorraine.fr/public/SCD_T_1997_0210_LACROIX.pdf.
Повний текст джерелаThe work presented here gives the characteristics of the laser induced-plasma plume created during laser welding. First, in the experimental part of the study, we have used the emission spectroscopy to determinate the electron temperature and the density of the plasma. Several tests have been achieved. We have estimated the influence of welding parameters such as : the laser power, the nature of the shielding gas, the pulse duration. These measurements have been achieved on stainless steel, but also on pure metals (Fe, Cr, Ni, Mo, Nb). The emission spectroscopy is used to analyse the welding defects, in order to achieve real time control of the process. Experiments have shown that geometrical and chemical (grease) defectiveness can be detected. The second part of this work is devoted to the numerical model used to describe the laser-plasma interaction. Several models are presented. The calculation of the partition function of each element of the plasma plume allows the theoretical determination of the densities. Then we can estimate the optical properties of the plume (absorption coefficient and refractive index). Electron microscopy measurements of the plasma plume deposits show the presence of sma1l particles. Consequently, we apply the Mie's theory in arder to study the laser beam scattering in the plume. Finally, we model the radiative transfer in the plasma using a discrete ordinate scheme. The numerical results point out the major effect of the scattering on the temperature field in the plume. This model can be used in complement of those calculating the geometry of the weld seam