Download or read book Ion acceleration from relativistic laser nano target interaction written by Daniel Jung and published by . This book was released on 2012 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book New Ion Acceleration Mechanisms in Relativistic Laser nanotarget Interactions written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Relativistically Intense Laser Microplasma Interactions written by Tobias Ostermayr and published by Springer. This book was released on 2019-07-16 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation covers several important aspects of relativistically intense laser–microplasma interactions and some potential applications. A Paul-trap based target system was developed to provide fully isolated, well defined and well positioned micro-sphere-targets for experiments with focused peta-watt laser pulses. The laser interaction turned such targets into microplasmas, emitting proton beams with kinetic energies exceeding 10 MeV. The proton beam kinetic energy spectrum and spatial distribution were tuned by variation of the acceleration mechanism, reaching from broadly distributed spectra in relatively cold plasma expansions to spectra with relative energy spread as small as 20% in spherical multi-species Coulomb explosions and in directed acceleration processes. Numerical simulations and analytical calculations support these experimental findings and show how microplasmas may be used to engineer laser-driven proton sources. In a second effort, tungsten micro-needle-targets were used at a peta-watt laser to produce few-keV x-rays and 10-MeV-level proton beams simultaneously, both measured to have only few-μm effective source-size. This source was used to demonstrate single-shot simultaneous radiographic imaging with x-rays and protons of biological and technological samples. Finally, the dissertation discusses future perspectives and directions for laser–microplasma interactions including non-spherical target shapes, as well as thoughts on experimental techniques and advanced quantitative image evaluation for the laser driven radiography.

Download or read book Proton Acceleration in Ultra Relativistic Laser Plasma Interaction written by Tong-Pu Yu and published by LAP Lambert Academic Publishing. This book was released on 2012 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the rapid development of laser systems, plasma-based laser-driven ion acceleration has drawn increasing attention these years. In this book, one of the most efficient and promising ion acceleration mechanisms, so-called radiation pressure acceleration or light-sail regime is re-visited and studied in detail by theoretical analysis and multi-dimensional particle-in-cell (PIC) simulations. Based on a simple "flying plasma mirror" model, accurate scaling laws of the final ion energy, velocity, momentum, and energy coupling efficiency in the light-sail regime have been derived. For smooth proton acceleration, a shaped foil target or a density-modulated foil target is suggested to overcome the foil deformation when a transversely Gaussian laser pulse irradiates the foil. GeV proton beams can be generated with a well-defined quasi-monoenergetic feature in the energy spectrum. For stable proton acceleration in the light-sail regime, a two-ion-species shaped foil target is proposed and demonstrated by a series of PIC simulations. Hard X-ray gernation and attosecond electron beams are also stuided and verified in the light-sail regime.

Download or read book Ion acceleration and extreme light field generation based on ultra short and ultra intense lasers written by Liangliang Ji and published by Springer Science & Business Media. This book was released on 2014-01-23 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is dedicated to the relativistic (laser intensity above 1018 W/cm2) laser-plasma interactions, which mainly concerns two important aspects: ion acceleration and extreme-light-field (ELF). Based on the ultra-intense and ultra–short CP lasers, this book proposes a new method that significantly improves the efficiency of heavy-ion acceleration, and deals with the critical thickness issues of light pressure acceleration. More importantly, a series of plasma approaches for producing ELFs, such as the relativistic single-cycle laser pulse, the intense broad-spectrum chirped laser pulse and the ultra-intense isolated attosecond (10-18s) pulse are introduced. This book illustrates that plasma not only affords a tremendous accelerating gradient for ion acceleration but also serves as a novel medium for ELF generation, and hence has the potential of plasma-based optics, which have a great advantage on the light intensity due to the absence of device damage threshold.

Download or read book Laser Ion Acceleration from the Interaction of Ultra Intense Laser Pulse with Thi Foils written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The discovery that ultra-intense laser pulses (I> 10[sup 18] W/cm[sup 2]) can produce short pulse, high energy proton beams has renewed interest in the fundamental mechanisms that govern particle acceleration from laser-solid interactions. Experiments have shown that protons present as hydrocarbon contaminants on laser targets can be accelerated up to energies> 50 MeV. Different theoretical models that explain the observed results have been proposed. One model describes a front-surface acceleration mechanism based on the ponderomotive potential of the laser pulse. At high intensities (I> 10[sup 18] W/cm[sup 2]), the quiver energy of an electron oscillating in the electric field of the laser pulse exceeds the electron rest mass, requiring the consideration of relativistic effects. The relativistically correct ponderomotive potential is given by U[sub p] = ([1 + I[lambda][sup 2]/1.3 x 10[sup 18]][sup 1/2] - 1) m[sub o]c[sup 2], where I[lambda][sup 2] is the irradiance in W[micro]m[sup 2]/cm[sup 2] and m[sub o]c[sup 2] is the electron rest mass. At laser irradiance of I[lambda][sup 2] [approx] 10[sup 20] W[micro]m[sup 2]/cm[sup 2], the ponderomotive potential can be of order several MeV. A few recent experiments--discussed in Chapter 3 of this thesis--consider this ponderomotive potential sufficiently strong to accelerate protons from the front surface of the target to energies up to tens of MeV. Another model, known as Target Normal Sheath Acceleration (TNSA), describes the mechanism as an electrostatic sheath on the back surface of the laser target. According to the TNSA model, relativistic hot electrons created at the laser-solid interaction penetrate the foil where a few escape to infinity. The remaining hot electrons are retained by the target potential and establish an electrostatic sheath on the back surface of the target.

Download or read book Relativistic Electron Mirrors written by Daniel Kiefer and published by Springer. This book was released on 2014-07-25 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: A dense sheet of electrons accelerated to close to the speed of light can act as a tuneable mirror that can generate bright bursts of laser-like radiation in the short wavelength range simply via the reflection of a counter-propagating laser pulse. This thesis investigates the generation of such a relativistic electron mirror structure in a series of experiments accompanied by computer simulations. It is shown that such relativistic mirror can indeed be created from the interaction of a high-intensity laser pulse with a nanometer-scale, ultrathin foil. The reported work gives a intriguing insight into the complex dynamics of high-intensity laser-nanofoil interactions and constitutes a major step towards the development of a relativistic mirror, which could potentially generate bright burst of X-rays on a micro-scale.

Download or read book Ion Acceleration from the Interaction of Ultra Intense Lasers with Solid Foils written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The discovery that ultra-intense laser pulses (I> 10[sup 18] W/cm[sup 2]) can produce short pulse, high energy proton beams has renewed interest in the fundamental mechanisms that govern particle acceleration from laser-solid interactions. Experiments have shown that protons present as hydrocarbon contaminants on laser targets can be accelerated up to energies> 50 MeV. Different theoretical models that explain the observed results have been proposed. One model describes a front-surface acceleration mechanism based on the ponderomotive potential of the laser pulse. At high intensities (I> 10[sup 18] W/cm[sup 2]), the quiver energy of an electron oscillating in the electric field of the laser pulse exceeds the electron rest mass, requiring the consideration of relativistic effects. The relativistically correct ponderomotive potential is given by U[sub p] = ([1 + I[lambda][sup 2]/1.3 x 10[sup 18]][sup 1/2] - 1) m[sub o]c[sup 2], where I[lambda][sup 2] is the irradiance in W [micro]m[sup 2]/cm[sup 2] and m[sub o]c[sup 2] is the electron rest mass. At laser irradiance of I[lambda][sup 2] [approx] 10[sup 20] W [micro]m[sup 2]/cm[sup 2], the ponderomotive potential can be of order several MeV. A few recent experiments--discussed in Chapter 3 of this thesis--consider this ponderomotive potential sufficiently strong to accelerate protons from the front surface of the target to energies up to tens of MeV. Another model, known as Target Normal Sheath Acceleration (TNSA), describes the mechanism as an electrostatic sheath on the back surface of the laser target. According to the TNSA model, relativistic hot electrons created at the laser-solid interaction penetrate the foil where a few escape to infinity. The remaining hot electrons are retained by the target potential and establish an electrostatic sheath on the back surface of the target. In this thesis we present several experiments that study the accelerated ions by affecting the contamination layer from which they originate. Radiative heating was employed as a method of removing contamination from palladium targets doped with deuterium. We present evidence that ions heavier than protons can be accelerated if hydrogenous contaminants that cover the laser target can be removed. We show that deuterons can be accelerated from the deuterated-palladium target, which has been radiatively heated to remove contaminants. Impinging a deuteron beam onto a tritiated-titanium catcher could lead to the development of a table-top source of short-pulse, 14-MeV fusion neutrons. We also show that by using an argon-ion sputter gun, contaminants from one side of the laser target can be selectively removed without affecting the other side. We show that irradiating a thin metallic foil with an ultra-intense laser pulse produces a proton beam with a yield of 1.5-2.5 10[sup 11] and temperature, kT = 1.5 MeV with a maximum proton energy> 9 MeV. Removing contaminants from the front surface of the laser target with an argon-ion sputter gun, had no observable effect on the proton beam. However, removing contaminants from the back surface of the laser target reduced the proton beam by two orders of magnitude to, at most, a yield of [approx] 10[sup 9] and a maximum proton energy 4 MeV. Based on these observations, we conclude that the majority ( 99%) of high energy protons (E> 5 MeV) from the interaction of an ultra-intense laser pulse with a thin foil originate on the back surface of the foil--as predicted by the TNSA model. Our experimental results are in agreement with PIC simulations showing back surface protons reach energies up to 13 MeV, while front surface protons reach a maximum energy of 4 MeV. Well diagnosed and controllable proton beams will have many applications: neutron radiography, material damage studies, production of medical isotopes, and as a high-resolution radiography tool for diagnosing opaque materials and plasmas. Well collimated and focusable ion beams may also prove beneficial for alternative inertial-fusion concepts such as proton fast ignition, a potentially viable method for achieving a controlled fusion reaction in the laboratory earlier than expected.

Download or read book Laser to hot electron Conversion Limitations in Relativistic Laser Matter Interactions Due to Multi picosecond Dynamics written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High-energy short-pulse lasers are pushing the limits of plasma-based particle acceleration, x-ray generation, and high-harmonic generation by creating strong electromagnetic fields at the laser focus where electrons are being accelerated to relativistic velocities. Understanding the relativistic electron dynamics is key for an accurate interpretation of measurements. We present a unified and self-consistent modeling approach in quantitative agreement with measurements and differing trends across multiple target types acquired from two separate laser systems, which differ only in their nanosecond to picosecond-scale rising edge. Insights from high-fidelity modeling of laser-plasma interaction demonstrate that the ps-scale, orders of magnitude weaker rising edge of the main pulse measurably alters target evolution and relativistic electron generation compared to idealized pulse shapes. This can lead for instance to the experimentally observed difference between 45 MeV and 75 MeV maximum energy protons for two nominally identical laser shots, due to ps-scale prepulse variations. Our results indicate that the realistic inclusion of temporal laser pulse profiles in modeling efforts is required if predictive capability and extrapolation are sought for future target and laser designs or for other relativistic laser ion acceleration schemes.

Download or read book Target Station Optimization for the High Brilliance Neutron Source HBS written by Jan Philipp Dabruck and published by Springer. This book was released on 2018-12-29 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the present work, the target station of the accelerator-driven neutron source HBS is optimized in comprehensive parameter studies using the Monto-Carlo method. The dependence of the most important performance characteristics of such a system on the external parameters is investigated neglecting technical and mechanical limitations. In this way, qualitative and quantitative statements for all possible configurations and envisaged applications can be derived and should be considered in the detailed planning of such facilities. For this purpose, different scenarios are considered that place completely different requirements on the design of the target station. The central statements derived in this thesis can be transferred to any framework conditions, such as different accelerator energies, so that these results can be used in the development of other neutron sources, which together with the HBS form a European network and provide a prosperous community in neutron science.

Download or read book Mechanism and Control of High intensity laser driven Ion Acceleration written by Teh Lin and published by . This book was released on 2005 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Review of Multi dimensional Large scale Kinetic Simulation and Physics Validation of Ion Acceleration in Relativistic Laser matter Interaction written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Two new experimental technologies enabled realization of Break-out afterburner (BOA) - High quality Trident laser and free-standing C nm-targets. VPIC is an powerful tool for fundamental research of relativistic laser-matter interaction. Predictions from VPIC are validated - Novel BOA and Solitary ion acceleration mechanisms. VPIC is a fully explicit Particle In Cell (PIC) code: models plasma as billions of macro-particles moving on a computational mesh. VPIC particle advance (which typically dominates computation) has been optimized extensively for many different supercomputers. Laser-driven ions lead to realization promising applications - Ion-based fast ignition; active interrogation, hadron therapy.

Download or read book Collective Charged Particle Dynamics in Relativistically Transparent Laser plasma Interactions written by Bruno González-Izquierdo and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis reports on experimental and numerical investigations of the collective response of electrons and ions to the interaction of ultra-intense (1020 Wcm−2) laser with ultra-thin (nanometre scale) foils undergoing expansion and relativistic induced transparency. The onset of this relativistic mechanism is also characterised and studied in detail. This new insight into relativistic transparency is an important step towards optical control of charged particle dynamics in laser driven dense plasma sources and in its potential applications; including ion and radiation source development.The experimental and numerical investigations exploring the onset and the underpinning physics of the relativistic transparency have focused on its dependency on the target areal density, laser intensity and polarisation. The results show a maximum laser transmission for the thinnest targets investigated, which decreases exponentially with increasing target thickness. The same trend is obtained for linearly and circularly polarised laser light. However, for a given target thickness, the linear polarisation case exhibits a significantly higher transmission fraction, with respect to the circular polarisation case, due to additional electron heating and expansion. Moreover, it is shown that for the thinnest targets, once they become relativistically transparent, the transmitted light fraction increases rapidly as the laser intensity increases. The increasing rate is shown to be more pronounced in the thinnest targets investigated. This is diagnosed by measurement of both the fundamental and second harmonic wavelengths. An alternative approach, based on numerical measurement of the critical surface velocity, as a function of time, for various target thickness, and comparing it with corresponding analytical models is also proposed. The onset of relativistic induced transparency is found to curb the radiation pressure effciency of the charged particle acceleration mechanism.Investigations of the collective response of electrons in ultra-thin foils undergoing transparency show that a 'relativistic plasma aperture' is generated by intense laser light in this regime, resulting in the fundamental optical phenomenon of diffraction. It is numerically found that the plasma electrons collectively respond to the resulting laser near-field diffraction pattern, resulting in a beam of energetic electrons with spatial-intensity distribution, related to this diffraction structure, which can be controlled by variation of the laser pulse parameters,and in turn the onset of relativistic transparency. Additionally, it is shown that static electron beam, and induced magnetic field, structures can be made to rotate at fixed or variable angular frequencies depending on the degree of ellipticity in the laser polarisation. The predicted electron beam distributions using the 'relativistic plasma aperture' concept are verified experimentally.Understanding the collective response of plasma electrons to transparency and how this affects the subsequent acceleration of ions is highly important to the interpretation of experiments exploring ion acceleration employing ultra-thin foils. Control of this collective electron motion, and thus the resultant electrostatic fields, could enable unprecedented control over the spatial-intensity distribution of laser-driven ion acceleration. The results presented in this thesis show that in ultra-thin foils undergoing transparency the electron dynamics are mapped onto the beam of protons accelerated via strong charge-separation-induced electrostatic fields. It is demonstrated that the degree of ellipticity of the laser polarisation defines the spatial-intensity distribution of the proton beam profile and can therefore be used to control it. This demonstration of dynamic optical control of structures within the spatial-intensity distribution of the beam of laser accelerated ions opens a new route to optimising the properties of these promising ion sources.

Download or read book Ion Acceleration from the Interaction of Ultra intense Lasers with Solid Foils written by Matthew Mark Allen and published by . This book was released on 2004 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser Pulses written by Igor Peshko and published by BoD – Books on Demand. This book was released on 2012-10-17 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses aspects of laser pulses generation, characterization, and practical applications. Some new achievements in theory, experiments, and design are demonstrated. The introductive chapter shortly overviews the physical principles of pulsed lasers operation with pulse durations from seconds to yoctoseconds. A theory of mode-locking, based on the optical noise concept, is discussed. With this approximation, all paradoxes of ultrashort laser pulse formation have been explained. The book includes examples of very delicate laser operation in biomedical areas and extremely high power systems used for material processing and water purification. We hope this book will be useful for engineers and managers, for professors and students, and for those who are interested in laser science and technologies.

Download or read book Ultra high contrast Laser Acceleration of Relativistic Electrons in Solid Targets written by Drew Pitney Higginson and published by . This book was released on 2013 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cone-guided fast ignition approach to Inertial Confinement Fusion requires laser-accelerated relativistic electrons to deposit kilojoules of energy within an imploded fuel core to initiate fusion burn. One obstacle to coupling electron energy into the core is the ablation of material, known as preplasma, by laser energy proceeding nanoseconds prior to the main pulse. This causes the laser-absorption surface to be pushed back hundreds of microns from the initial target surface; thus increasing the distance that electrons must travel to reach the imploded core. Previous experiments have shown an order of magnitude decrease in coupling into surrogate targets when intentionally increasing the amount of preplasma. Additionally, for electrons to deposit energy within the core, they should have kinetic energies on the order of a few MeV, as less energetic electrons will be stopped prior to the core and more energetic electrons will pass through the core without depositing much energy. Thus a quantitative understanding of the electron energy spectrum and how it responds to varied laser parameters is paramount for fast ignition. For the first time, this dissertation quantitatively investigates the acceleration of electrons using an ultra-high-contrast laser. Ultra-high-contrast lasers reduce the laser energy that reaches the target prior to the main pulse; drastically reducing the amount of preplasma. Experiments were performed in a cone-wire geometry relevant to fast ignition. These experiments irradiated the inner-tip of a Au cone with the laser and observed electrons that passed through a Cu wire attached to the outer-tip of the cone. The total emission of K[alpha] x-rays is used as a diagnostic to infer the electron energy coupled into the wire. Imaging the x-ray emission allowed an effective path-length of electrons within the wire to be determined, which constrained the electron energy spectrum. Experiments were carried out on the ultra-high-contrast Trident laser at Los Alamos National Laboratory and at the low-contrast Titan laser at Lawrence Livermore National Laboratory. The targets were irradiated using these 1.054 [mu]m wavelength lasers at intensities from 1019 to 1020 W/cm2. The coupling of energy into the Cu wire was found to be 2.7x higher when the preplasma was reduced using high-contrast. Additionally, higher laser intensity elongated the effective path-length of electrons within the wire, indicating that their kinetic energy was higher. To understand the physics behind laser-acceleration of electrons and to examine how this mechanism is affected by the presence of preplasma, simulations were performed to model the laser interaction. This simulations modeled the interaction using a 0.1 to 3 [mu]m exponential preplasma scale length for the high-contrast cases and hydronamically simulated longer scale preplasma (~25 [mu]m) for the low-contrast case. The simulations show that absorption of laser light increases from only 20% with a 0.1 [mu]m scale length to nearly 90% with a long low-contrast-type preplasma. However, as observed in experiments, a smaller fraction of this absorbed energy is transported to the diagnostic wire, which is due to an increased distance that the electrons must travel to reach the wire and increase angular divergence of the electrons. The simulations show that increasing the preplasma scale length from 0.1 to 3 [mu]m increases the average energy by a factor of 2.5x. This is consistent with an increased interaction length over which the electrons can gain energy from the laser. The simulated electrons are compared with experimental data by injecting them into another simulation modeling the transport of electrons through the cone-wire target. This method quantitatively reproduced the experimentally measured the K[alpha] x-ray emission profiles in the high-contrast cases, which gives confidence in the simulations and the generated electron distributions. By showing that the reduction of preplasma increases coupling into surrogate targets this work shows a significant advantage for the fast ignition scheme. Such work gives confidence to facilities that increasing the contrast of their laser systems will increase electron coupling. Additionally, detailed investigation of these high-contrast systems will aid researchers in understanding the effect that preplasma has on the acceleration of electrons.

Download or read book Ion Acceleration Beyond 100MeV amu from Relativistic Laser matter Interactions written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: