Download or read book Fast Electron Energy Transport in High Intensity Laser plasma Interactions written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Theory and Modelling of Fast Electron Transport in Laser plasma Interactions written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Acceleration and Transport of Electrons Generated by Intense Laser Plasma Interactions at Sharp Interfaces written by Joshua Joseph May and published by . This book was released on 2017 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: The continued development of the chirped pulse amplification technique has allowed for the development of lasers with powers of in excess of $10^{15}W$, for pulse lengths with durations of between .01 and 10 picoseconds, and which can be focused to energy densities greater than 100 giga-atmospheres. When such lasers are focused onto material targets, the possibility of creating particle beams with energy fluxes of comparable parameters arises. Such interactions have a number of theorized applications. For instance, in the Fast Ignition concept for Inertial Confinement Fusion \cite{Tabak:1994vx}, a high-intensity laser efficiently transfers its energy into an electron beam with an appropriate spectra which is then transported into a compressed target and initiate a fusion reaction. Another possible use is the so called Radiation Pressure Acceleration mechanism, in which a high-intensity, circularly polarized laser is used to create a mono-energetic ion beam which could then be used for medical imaging and treatment, among other applications. For this latter application, it is important that the laser energy is transferred to the ions and not to the electrons. However the physics of such high energy-density laser-matter interactions is highly kinetic and non-linear, and presently not fully understood. In this dissertation, we use the Particle-in-Cell code OSIRIS \cite{Fonseca:2002, Hemker:1999} to explore the generation and transport of relativistic particle beams created by high intensity lasers focused onto solid density matter at normal incidence. To explore the generation of relativistic electrons by such interactions, we use primarily one-dimensional (1D) and two-dimensional (2D), and a few three-dimensional simulations (3D). We initially examine the idealized case of normal incidence of relatively short, plane-wave lasers on flat, sharp interfaces. We find that in 1D the results are highly dependent on the initial temperature of the plasma, with significant absorption into relativistic electrons only possible when the temperature is high in the direction parallel to the electric field of the laser. In multi-dimensions, absorption into relativistic electrons arises independent of the initial temperature for both fixed and mobile ions, although the absorption is higher for mobile ions. In most cases however, absorption remains at $10's$ of percent, and as such a standing wave structure from the incoming and reflected wave is setup in front of the plasma surface. The peak momentum of the accelerated electrons is found to be $2 a_0 m_e c$, where $a_0 \equiv e A_0/m_e c^2$ is the normalized vector potential of the laser in vacuum, $e$ is the electron charge, $m_e$ is the electron mass, and $c$ is the speed of light. We consider cases for which $a_0>1$. We therefore call this the $2 a_0$ acceleration process. Using particle tracking, we identify the detailed physics behind the $2 a_0$ process and find it is related to the standing wave structure of the fields. We observe that the particles which gain energy do so by interacting with the laser electric field within a quarter wavelength of the surface where it is at an anti-node (it is a node at the surface). We find that only particles with high initial momentum -- in particular high transverse momentum -- are able to navigate through the laser magnetic field as its magnitude decreases in time each half laser cycle (it is an anti-node at the surface) to penetrate a quarter wavelength into the vacuum where the laser electric field is large. For a circularly polarized laser the magnetic field amplitude never decreases at the surface, instead its direction simply rotates. This prevents electrons from leaving the plasma and they therefore cannot gain energy from the electric field. For pulses with longer durations ($\gtrsim 250fs$), or for plasmas which do not have initially sharp interfaces, we discover that in addition to the $2 a_0$ acceleration at the surface, relativistic particles are also generated in an underdense region in front of the target. These particles have energies without a sharp upper bound. Although accelerating these particles removes energy from the incoming laser, and although the surface of the plasma does not stay perfectly flat and so the standing wave structure becomes modified, we find in most cases, the $2 a_0$ acceleration mechanism occurs similarly at the surface and that it still dominates the overall absorption of the laser. To explore the generation of relativistic electrons at a solid surface and transport of the heat flux of these electrons in cold or warm dense matter, we compare OSIRIS simulations with results from an experiment performed on the OMEGA laser system at the University of Rochester. In that experiment, a thin layer of gold placed on a slab of plastic is illuminated by an intense laser. A greater than order-of-magnitude decrease in the fluence of hot electrons is observed when those electrons are transported through a plasma created from a shock-heated plastic foam, as compared to transport through cold matter (unshocked plastic foam) at somewhat higher density. Our simulations indicate two reasons for the experimental result, both related to the magnetic field. The primary effect is the generation of a collimating B-field around the electron beam in the cold plastic foam, caused by the resistivity of the plastic. We use a Monte Carlo collision algorithm implemented in OSIRIS to model the experiment. The incoming relativistic electrons generate a return current. This generates a resistive electric field which then generates a magnetic field from Faraday's law. This magnetic field collimates the forward moving relativistic electrons. The collisionality of both the plastic and the gold are likely to be greater in the experiment than the 2D simulations where we used a lower density for the gold (to make the simulations possible) which heats up more. In addition, the use of 2D simulations also causes the plastic to heat up more than expected. We compensated for this by increasing the collisionality of the plasma in the simulations and this led to better agreement. The second effect is the growth of a strong, reflecting B-field at the edge of the plastic region in the shock heated material, created by the convective transport of this field back towards the beam source due to the neutralizing return current. Both effects appear to be caused primarily by the difference is density in the two cases. Owing to its higher heat capacity, the higher density material does not heat up as much from the heat flux coming from the gold, which leads to a larger resistivity. Lastly, we explored a numerical effect which has particular relevance to these simulations, due to their high energy and plasma densities. This effect is caused by the use of macro particles (which represent many real particles) which have the correct charge to mass ratio but higher charge. Therefore, any physics of a single charge that scales as $q^2/m$ will be artificially high. Physics that involves scales smaller than the macro-particle size can be mitigated through the use of finite size particles. However, for relativistic particles the spatial scale that matters is the skin depth and the cell sizes and particle sizes are both smaller than this. This allows the wakes created by these particles to be artificially high which causes them to slow down much faster than a single electron. We studied this macro-particle stopping power theoretically and in OSIRIS simulations. We also proposed a solution in which particles are split in to smaller particles as they gain energy. We call this effect Macro Particle Stopping. Although this effect can be mitigated by using more particles, this is not always computationally efficient. We show how it can also be mitigated by using high-order particle shapes, and/or by using a particle-splitting method which reduces the charge of only the most energetic electrons.

Download or read book Laser Plasma Interactions and Applications written by Paul McKenna and published by Springer Science & Business Media. This book was released on 2013-03-29 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser-Plasma Interactions and Applications covers the fundamental and applied aspects of high power laser-plasma physics. With an internationally renowned team of authors, the book broadens the knowledge of young researchers working in high power laser-plasma science by providing them with a thorough pedagogical grounding in the interaction of laser radiation with matter, laser-plasma accelerators, and inertial confinement fusion. The text is organised such that the theoretical foundations of the subject are discussed first, in Part I. In Part II, topics in the area of high energy density physics are covered. Parts III and IV deal with the applications to inertial confinement fusion and as a driver of particle and radiation sources, respectively. Finally, Part V describes the principle diagnostic, targetry, and computational approaches used in the field. This book is designed to give students a thorough foundation in the fundamental physics of laser-plasma interactions. It will also provide readers with knowledge of the latest research trends and elucidate future exciting challenges in laser-plasma science.

Download or read book The evolution of two dimensional effects in fast electron transport from high intensity laser plasma interactions written by and published by . This book was released on 1982 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Frontiers in High Energy Density Physics written by National Research Council and published by National Academies Press. This book was released on 2003-05-11 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent scientific and technical advances have made it possible to create matter in the laboratory under conditions relevant to astrophysical systems such as supernovae and black holes. These advances will also benefit inertial confinement fusion research and the nation's nuclear weapon's program. The report describes the major research facilities on which such high energy density conditions can be achieved and lists a number of key scientific questions about high energy density physics that can be addressed by this research. Several recommendations are presented that would facilitate the development of a comprehensive strategy for realizing these research opportunities.

Download or read book Fast Electron Transport in Overdense Laser induced Plasmas written by Jeremy Martin Hill and published by . This book was released on 2003 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Evolution of Two dimensional Effects in Fast Electron Transport from High Intensity Laser Plasma Interactions written by F. Amiranoff and published by . This book was released on 1982 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser Plasma Theory and Simulation written by Hector A. Baldis and published by CRC Press. This book was released on 2020-05-05 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers recent developments in laser plasma physics such as absorption, instability, energy transport and radiation from the standpoint of theory and simulation for plasma corona, showing how the elements for the high density compression depend on the interaction physics and heat transport.

Download or read book Integrated Kinetic Simulation of Laser Plasma Interactions Fast Electron Generation and Transport in Fast Ignition written by and published by . This book was released on 2009 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present new results on the physics of short-pulse laser-matter interaction of kilojoule-picosecond pulses at full spatial and temporal scale, using a new approach that combines a 3D collisional electromagnetic Particle-in-Cell code with an MHD-hybrid model of high-density plasma. In the latter, collisions damp out plasma waves, and an Ohm's law with electron inertia effects neglected determines the electric field. In addition to yielding orders of magnitude in speed-up while avoiding numerical instabilities, this allows us to model the whole problem in a single unified framework: the laser-plasma interaction at sub-critical densities, energy deposition at relativistic critical densities, and fast-electron transport in solid densities. Key questions such as the multi-picosecond temporal evolution of the laser energy conversion into hot electrons, the impact of return currents on the laser-plasma interaction, and the effect of self-generated electric and magnetic fields on electron transport will be addressed. We will report applications to current experiments.

Download or read book Laser Plasma Interactions 4 written by M.B Hooper and published by CRC Press. This book was released on 2020-11-26 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser-Plasma Interactions 4 is the fourth book in a series devoted to the study of laser-plasma interactions. Subjects covered include laser light propagation, instabilities, compression and hydrodynamics, spectroscopy, diagnostics, computer code, dense plasmas, high-power lasers, X-UV sources and lasers, beat waves, and transport processes.

Download or read book The Effects of Pre formed Plasma on the Generation and Transport of Fast Electrons in Relativistic Laser solid Interactions written by Bhooshan S. Paradkar and published by . This book was released on 2012 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis we present the dynamics of relativistic fast electrons produced in the laser-solid interactions at the intensities greater than 1018 W/cm2. In particular, the effects of pre-formed plasma in front of a solid target on the generation and transport of these fast electrons is studied. The presence of such a pre-formed plasma is ubiquitous in almost all the present short pulse high intensity laser-solid interaction experiments. First, the generation of fast electrons in the presence of pre-formed plasma of varying density scale-lengths is studied with the help of Particle In Cell (PIC) simulations. It is shown that the fast electrons energy increases with the increasing pre-formed plasma, consistent with the experimental observations. The possible mechanism of generation of such energetic electrons is studied. It is proposed that the interaction of plasma electrons with the laser in the presence of ambipolar electric field, generated due to the laser heating, can result in the electron acceleration beyond laser ponderomotive energy. The analytical and numerical studies of this heating mechanism are presented. In the second part of thesis, the influence of pre-formed plasma on the fast electrons transport is studied. Especially the physics of refluxing of these fast electrons due to the excitation of electrostatic sheath fields inside the pre-formed plasma is investigated. It is shown that this refluxing is responsible for the `annular ring shaped' copper K[alpha] x-ray emission observed in the recent high intensity laser-solid experiments.

Download or read book The Interaction of High Power Lasers with Plasmas written by Shalom Eliezer and published by CRC Press. This book was released on 2002-08-16 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Interaction of High-Power Lasers with Plasmas provides a thorough self-contained discussion of the physical processes occurring in laser-plasma interactions, including a detailed review of the relevant plasma and laser physics. The book analyzes laser absorption and propagation, electron transport, and the relevant plasma waves in detail. It al

Download or read book Laser Plasma Theory and Simulation written by Hector A. Baldis and published by CRC Press. This book was released on 1994-06-01 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers recent developments in laser plasma physics such as absorption, instability, energy transport and radiation from the standpoint of theory and simulation for plasma corona, showing how the elements for the high density compression depend on the interaction physics and heat transport.

Download or read book Laser Plasma Interactions written by Dino A. Jaroszynski and published by Taylor & Francis. This book was released on 2009-03-27 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents diagnostic methods, experimental techniques, and simulation tools used to study and model laser-plasma interactions. This book discusses the basic theory of the interaction of intense electromagnetic radiation fields with matter.

Download or read book Applications of Laser Plasma Interactions written by Shalom Eliezer and published by CRC Press. This book was released on 2008-12-22 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent advances in the development of lasers with more energy, power, and brightness have opened up new possibilities for exciting applications. Applications of Laser-Plasma Interactions reviews the current status of high power laser applications. The book first explores the science and technology behind the ignition and burn of imploded fusion fue

Download or read book Resistive Guiding of Fast Electrons in High intensity Laser plasma Interactions written by Damon Farley and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: