Download or read book Proof Of Principle Experiment for Laser Driven Acceleration of Relativistic Electrons in a Semi Infinite Vacuum written by and published by . This book was released on 2006 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: We recently achieved the first experimental observation of laser-driven particle acceleration of relativistic electrons from a single Gaussian near-infrared laser beam in a semi-infinite vacuum. This article presents an in-depth account of key aspects of the experiment. An analysis of the transverse and longitudinal forces acting on the electron beam is included. A comparison of the observed data to the acceleration viewed as an inverse transition radiation process is presented. This is followed by a detailed description of the components of the experiment and a discussion of future measurements.

Download or read book First Observations of Laser Driven Acceleration of Relativistic Electrons in a Semi Infinite Vacuum Space written by J. E. Spencer and published by . This book was released on 2006 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have observed acceleration of relativistic electrons in vacuum driven by a linearly polarized visible laser beam incident on a thin gold-coated reflective boundary. The observed energy modulation effect follows all the characteristics expected for linear acceleration caused by a longitudinal electric field. As predicted by the Lawson-Woodward theorem the laser driven modulation only appears in the presence of the boundary. It shows a linear dependence with the strength of the electric field of the laser beam and also it is critically dependent on the laser polarization. Finally, it appears to follow the expected angular dependence of the inverse transition radiation process. experiment as the Laser Electron Accelerator Project (LEAP).

Download or read book Proof of principle Experiment for Crossed Laser Beam Electron Acceleration in a Dielectric Loaded Vacuum Structure written by Tomas Plettner and published by . This book was released on 2002 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser driven Electron Acceleration in Infinite Vacuum written by Liang Jie Wong and published by . This book was released on 2011 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: I first review basic models for laser-plasma interaction that explain electron acceleration and beam confinement in plasma. Next, I discuss ponderomotive electron acceleration in infinite vacuum, showing that the transverse scattering angle of the accelerated electron may be kept small with a proper choice of parameters. I then analyze the direct (a.k.a. linear) acceleration of an electron in infinite vacuum by a pulsed radially-polarized laser beam, consequently demonstrating the possibility of accelerating an initially-relativistic electron in vacuum without the use of ponderomotive forces or any optical devices to terminate the laser field. As the Lawson-Woodward theorem has sometimes been cited to discount the possibility of net energy transfer from a laser pulse to a relativistic particle via linear acceleration in unbounded vacuum, I derive an analytical expression (which I verify with numerical simulation results) defining the regime where the Lawson-Woodward theorem in fact allows for this. Finally, I propose a two-color laser-driven direct acceleration scheme in vacuum that can achieve electron acceleration exceeding 90% of the one-color theoretical energy gain limit, over twice of what is possible with a one-color pulsed beam of equal total energy and pulse duration.

Download or read book Advanced Accelerator Concepts written by Manoel Conde and published by American Institute of Physics. This book was released on 2006-12-13 with total page 954 pages. Available in PDF, EPUB and Kindle. Book excerpt: This workshop covered the general field of advanced particle accelerators, exploring the science and technology of a multitude of novel acceleration schemes. Various schemes under study utilize combinations of plasmas, laser beams, dielectric materials, and RF power. The development of technologies that will enable the design of future high energy physics machines is the underlying goal of this workshop.

Download or read book Production Characterization and Acceleration of Optical Microbunches written by Christopher M. S. Sears and published by . This book was released on 2008 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book First Observation of Laser Driven Particle Acceleration in a Semi Infinite Vacuum Space written by J. E. Spencer and published by . This book was released on 2005 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Physics Experiment for a Laser Driven Electron Accelerator written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A physics experiment for laser-driven, electron acceleration in a structure loaded vacuum is being carried out at Stanford University. The experiment is to demonstrate the linear dependence of the electron energy gain on the laser field strength. The accelerator structure, made of dielectric, is semi-open, with dimensions a few thousand times the laser wavelength. The electrons traverse the axis of two crossed laser beams to obtain acceleration within a coherence distance. We predict that the demonstration experiment will produce a single-stage, electron energy gain of 300 keV over a 2.5 mm distance. Ultimately, acceleration gradients of 1 GeV/m should be possible.

Download or read book Proposed Physics Experiments for Laser Driven Electron Linear Acceleration in a Dielectric Loaded Vacuum Final Report written by and published by . This book was released on 2016 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: This final report summarizes the last three years of research on the development of advanced linear electron accelerators that utilize dielectric wave-guide vacuum channels pumped by high energy laser fields to accelerate beams of electrons.

Download or read book Laser Driven Electron Acceleration in Vacuum Gases and Plasmas written by and published by . This book was released on 1996 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper discusses some of the important issues pertaining to laser acceleration in vacuum, neutral gases and plasmas. The limitations of laser vacuum acceleration as they relate to electron slippage, laser diffraction, material damage and electron aperture effects, are discussed. An inverse Cherenkov laser acceleration configuration is presented in which a laser beam is self guided in a partially ionized gas. Optical self guiding is the result of a balance between the nonlinear self focusing properties of neutral gases and the diffraction effects of ionization. The stability of self guided beams is analyzed and discussed. In addition, aspects of the laser wakefield accelerator are presented and laser driven accelerator experiments are briefly discussed.

Download or read book Research on Vacuum Laser Accelerator and Proof of principle Experiment written by Lei Shao and published by . This book was released on 2011 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics of Laser Driven Relativistic Plasmas Energetic X rays Proton Beams and Relativistic Electron Transport in Petawatt Laser Experiments written by Richard Adolph Snavely and published by . This book was released on 2003 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structure Loaded Vacuum Laser Driven Particle Acceleration Experiments at SLAC written by and published by . This book was released on 2007 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present an overview of the future laser-driven particle acceleration experiments. These will be carried out at the E163 facility at SLAC. Our objectives include a reconfirmation of the proof-of-principle experiment, a staged buncher laser-accelerator experiment, and longer-term future experiments that employ dielectric laser-accelerator microstructures.

Download or read book Proof of principle Experiments of Laser Wakefield Acceleration written by and published by . This book was released on 1994 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recently there has been a great interest in laser-plasma accelerators as possible next-generation particle accelerators because of their potential for ultra high accelerating gradients and compact size compared with conventional accelerators. It is known that the laser pulse is capable of exciting a plasma wave propagating at a phase velocity close to the velocity of light by means of beating two-frequency lasers or an ultra short laser pulse. These schemes came to be known as the Beat Wave Accelerator (BWA) for beating lasers or as the Laser Wakefield Accelerator (LWFA) for a short pulse laser. In this paper, the principle of laser wakefield particle acceleration has been tested by the Nd:glass laser system providing a short pulse with a power of 10 TW and a duration of 1 ps. Electrons accelerated up to 18 MeV/c have been observed by injecting 1 MeV/c electrons emitted from a solid target by an intense laser impact. The accelerating field gradient of 30 GeV/m is inferred.

Download or read book Study of Transport of Laser driven Relativistic Electrons in Solid Materials written by Philippe Leblanc and published by . This book was released on 2013 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the ultra intense lasers available today, it is possible to generate very hot electron beams in solid density materials. These intense laser-matter interactions result in many applications which include the generation of ultrashort secondary sources of particles and radiation such as ions, neutrons, positrons, x-rays, or even laser-driven hadron therapy. For these applications to become reality, a comprehensive understanding of laser-driven energy transport including hot electron generation through the various mechanisms of ionization, and their subsequent transport in solid density media is required. This study will focus on the characterization of electron transport effects in solid density targets using the state-of- the-art particle-in-cell code PICLS. A number of simulation results will be presented on the topics of ionization propagation in insulator glass targets, non-equilibrium ionization modeling featuring electron impact ionization, and electron beam guiding by the self-generated resistive magnetic field. An empirically derived scaling relation for the resistive magnetic in terms of the laser parameters and material properties is presented and used to derive a guiding condition. This condition may prove useful for the design of future laser-matter interaction experiments.

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 Study of Relativistic Electrons Generated from Ultra intense Laser plasma Interaction Relevant to Laser Wakefield Acceleration and Fast Ignition Laser Fusion written by Mianzhen Mo and published by . This book was released on 2015 with total page 283 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultra-intense (> 10^18 W/cm^2) laser interaction with matter is capable of producing relativistic electrons which have a variety of applications in scientific and medical research. Knowledge of various aspects of these hot electrons is important in harnessing them for various applications. Of particular interest for this thesis is the investigation of hot electrons generated in the areas of Laser Wakefield Acceleration (LWFA) and Fast Ignition (FI). LWFA is a physical process in which electrons are accelerated by the strong longitudinal electrostatic fields that are formed inside the plasma cavities or wakes produced by the propagation of an ultra-intense laser pulse through an under-dense plasma. The accelerating E-fields inside the cavities are 1000 times higher than those of conventional particle accelerators and can accelerate electrons to the relativistic regime in a very short distance, on the order of a few millimeters. In addition, Betatron X-ray radiation can be produced from LWFA as a result of the transverse oscillations of the relativistic electrons inside the laser wakefield driven cavity. The pulse duration of Betatron radiation can be as short as a few femtoseconds, making it an ideal probe for measuring physical phenomena taking place on the time scale of femtoseconds. Experimental research on the electron acceleration of the LWFA has been conducted in this thesis and has led to the generation of mono-energetic electron bunches with peak energies ranging from a few hundreds of MeV to 1 GeV. In addition, the Betatron radiation emitted from LWFA was successfully characterized based on a technique of reflection off a grazing incidence mirror. Furthermore, we have developed a Betatron X-ray probe beamline based on the technique of K-shell absorption spectroscopy to directly measure the temporal evolution of the ionization states of warm dense aluminum. With this, we have achieved for the first time direct measurements of the ionization states of warm dense aluminum using Betatron X-ray radiation probing. Fast Ignition (FI) is an advanced scheme for inertial confinement fusion (ICF), in which the fuel ignition process is decoupled from its compression. Comparing with the conventional central hot-spot scheme for ICF, FI has the advantages of lower ignition threshold and higher gain. The success of FI relies on efficient energy coupling from the heating laser pulse to the hot electrons and subsequent transport of their energy to the compressed fuel. As a secondary part of this thesis, the transport of hot electrons in overdense plasma relevant to FI was studied. In particular, the effect of resistive layers within the target on the hot electron divergence and absorption was investigated. Experimental measurements were carried out and compared to simulations indicating minimal effect on the beam divergence but some attenuation through higher atomic number intermediate layers was observed.