Approved for public release; distribution is unlimited / A three dimensional analysis of the intensity distribution of backward optical transition radiation has been performed. The effects of variations in electron energy and beam divergence and on material properties such as dielectric permittivities and the resultant coherence length upon the angular distribution and polarization of optical transition radiation has been investigated. A surprising observation important to the use of optical transition radiation as a diagnostic tool for high energy electron beams is the behavior of the perpendicular component of the intensity. In contrast to low energies where the parallel component dominates, at electron energies above 200 MeV, the perpendicular component dominates. This requires the use of a polarization filter to diagnose particle beam properties at high energies. / http://archive.org/details/threedimensional00long / Lieutenant, United States Navy

Common methods for commissioning linear accelerators often neglect beam data for small fields. Examining the methods of beam data collection and modeling for commissioning linear accelerators revealed little to no discussion of the protocols for fields smaller than 4 cm x 4 cm. This leads to decreased confidence levels in the dose calculations and associated monitor units (MUs) for Intensity Modulated Radiation Therapy (IMRT). The parameters of commissioning the Novalis linear accelerator (linac) on the Eclipse Treatment Planning System (TPS) led to the study of challenges collecting data for very small fields. The focus of this thesis is the examination of the protocols for output factor collection and their impact on dose calculations by the TPS for IMRT treatment plans. Improving output factor collection methods, led to significant improvement in absolute dose calculations which correlated with the complexity of the plans. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

The Fermilab Tevatron is currently the world’s highest energy colliding beam facility. Its counter-rotating proton and antiproton beams collide at 2 TeV center-of-mass. Delivery of such intense beam fluxes to experiments has required improved knowledge of the Tevatron’s beam optical lattice. An oscillating dipole magnet, referred to as an AC dipole, is one of such a tool to non-destructively assess the optical properties of the synchrotron. We discusses development of an AC dipole system for the Tevatron, a fast-oscillating (f∼20 kHz) dipole magnet which can be adiabatically turned on and off to establish sustained coherent oscillations of the beam particles without affecting the transverse emittance. By utilizing an existing magnet and a higher power audio amplifier, the cost of the Tevatron AC dipole system became relatively inexpensive. We discuss corrections which must be applied to the driven oscillation measurements to obtain the proper interpretation of beam optical parameters from AC dipole studies. After successful operations of the Tevatron AC dipole system, AC dipole systems, similar to that in the Tevatron, will be build for the CERN LHC. We present several measurements of linear optical parameters (beta function and phase advance) for the Tevatron, as well as studies of non-linear perturbations from sextupole and octupole elements. / text

Thesis (M. Sc.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references (p. [167]-170). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

No description available.

A system is presented that is capable of confining an ion beam or plasma within a region that is essentially free of applied fields. An Artificially Structured Boundary (ASB) produces a spatially periodic set of magnetic field cusps that provides charged particle confinement. Electrostatic plugging of the magnetic field cusps enhances confinement. An ASB that has a small spatial period, compared to the dimensions of a confined plasma, generates electro- magneto-static fields with a short range. An ASB-lined volume thus constructed creates an effectively field free region near its center. It is assumed that a non-neutral plasma confined within such a volume relaxes to a Maxwell-Boltzmann distribution. Space charge based confinement of a second species of charged particles is envisioned, where the second species is confined by the space charge of the first non-neutral plasma species. An electron plasma confined within an ASB-lined volume can potentially provide confinement of a positive ion beam or positive ion plasma. Experimental as well as computational results are presented in which a plasma or charged particle beam interact with the electro- magneto-static fields generated by an ASB. A theoretical model is analyzed and solved via self-consistent computational methods to determine the behavior and equilibrium conditions of a relaxed plasma. The equilibrium conditions of a relaxed two species plasma are also computed. In such a scenario, space charge based electrostatic confinement is predicted to occur where a second plasma species is confined by the space charge of the first plasma species. An experimental apparatus with cylindrical symmetry that has its interior surface lined with an ASB is presented. This system was developed by using a simulation of the electro- magneto-static fields present within the trap to guide mechanical design. The construction of the full experimental apparatus is discussed. Experimental results that show the characteristics of electron beam transmission through the experimental apparatus are presented. A description of the experimental hardware and software used for trapping a charged particle beam or plasma is also presented.

Blister-Based Laser-Induced Forward-Transfer (BB LIFT) is a new method of particle transfer, capable of projecting complex and fragile particles into the gas phase. The technique uses a laser pulse to deform a metal or polymer film on a transparent substrate. The deformation of the film creates a blister which can mechanically desorb particles adhered to the surface. This thesis covers the study of the underlying mechanisms of blister formation in relation to laser pulse duration and film properties, whilst also advancing upon the technique by developing new methods for particle transfer of 0-dimensional point particles, 1-dimensional nanotubes, and 2-dimensional crystals. Study of the blister formation was carried out on uncoated 200-400 nm Titanium films, using 120 fs and 7 ns laser pulses. The blisters were studied by Atomic Force Microscopy and optical analysis. Furthermore a theoretical model for the blister formation using ns laser pulses was developed using a linear heat transfer model, showing a good agreement between experiment and theory. From this model mechanisms for blister formation under both of these pulse durations were developed. It was concluded that ns laser pulses heat the thin film causing it to undergo thermal expansion where the temperature and thermal expansion properties of the film define the blister. Femtosecond pulses form blisters due to confined ablation of the film at the interface of the transparent substrate and the film. The expanding gas forces the metal to stretch, where the deformation is dictated by the Young’s modulus of the material with the major factor being the thickness of the titanium film. The velocity distribution of the desorbed material was studied by means of mass spectroscopy. An ionising laser pulse was focused a known distance from the donor film. The ejected particles crossed the laser beam, and with a controlled delay of the time between the blister pulse and ionisation pulse the velocities could be determined for fullerenes (C60) and gold coated silicon nanoparticles (Auroshells). Utilising C60 as the desorbed material we could identify that for ns BB-LIFT the C60 was emitted at a velocity mostly dependent upon the heat expansion coefficient for the titanium film, resulting in a velocity approximating 100 ms-1 with a secondary emission of fullerenes due to evaporation from the hot surface. However, for fs BB-LIFT this evaporated emission was not present and the velocities could be adjusted from 7-70 ms-1 by varying the Ti film thickness from 360 nm to 210 nm respectively. These results are consistent with the mechanisms proposed earlier. The spread of the desorbed particle beam was also studied for nanosecond and femtosecond laser-induced blisters utilising auroshells and C60. This was accomplished by placing a receiver platform at a known distance in front of the donor film in order to collect the desorbed particles. The radial spread was then analysed indicating a flat deposit approximately the size of the initial blister with a 5 degree spread from that point. This indicates that the desorbed beam is highly directional. From this it could be ascertained that the blisters do not form from a single point position on the film but expand uniformly with the area of laser irradiation defining the growth point of the blister. A problem with many molecular beam techniques is that large fragile molecules or nanoparticles cannot be introduced to the gas phase without causing damage to the particles. Studies into the desorption of Auroshells (150 nm diameter), C60 (1 nm), PCBM (a fragile exohedral fullerene), carbon nanotubes (1x1000 nm), and 2D films (1x10000x10000 nm) showed that these materials were successfully transferred from the donor film to a receiver plate without causing damage to the particles. This was determined via Raman, NMR, AFM, and SEM measurements. Lastly a technique that allowed the growth of carbon nanotubes directly on the donor film utilising a a multi-layered substrate was developed, enabling the removal and deposition of the nanotubes, without exposing them to any chemical treatment.

An artificially structured boundary (ASB) produces a short-range, static electromagnetic field that can reflect charged particles. In the work presented, an ASB is considered to consist of a spatially periodic arrangement of electrostatically plugged magnetic cusps. When used to create an enclosed volume, an ASB may confine a non-neutral plasma that is effectively free of applied electromagnetic fields, provided the spatial period of the ASB-applied field is much smaller than any one dimension of the confinement volume. As envisioned, a non-neutral positron plasma could be confined by an ASB along its edge, and the space-charge of the positron plasma would serve to confine an antiproton plasma. If the conditions of the two-species plasma are suitable, production of antihydrogen via three-body recombination for antimatter gravity studies may be possible. A classical trajectory Monte Carlo (CTMC) simulation suite has been developed in C++ to efficiently simulate charged particle interactions with user defined electromagnetic fields. The code has been used to explore several ASB configurations, and a concept for a cylindrically symmetric ASB trap that employs a picket-fence magnetic field has been developed. Particle-in-cell (PIC) modeling has been utilized to investigate the confinement of non-neutral and partially neutralized positron plasmas in the trap.

Le présent travail de thèse porte sur la modélisation et la simulation, en domaine temporel, de l'interaction entre un faisceau d'électrons et une onde hyperfréquence dans la structure à onde lente d'un TOP à hélice. Puisque le TOP est un instrument surdimensionné, les modèles non-stationnaires généraux utilisés dans les codes commerciaux nécessitent de trop grosses ressources de calcul pour pouvoir être utilisés en un temps raisonnable dans un but de conception. Il est donc nécessaire de faire appel à des modèles spécialisés. Durant cette thèse, nous nous sommes intéressés au "modèle discret non-stationnaire d'excitation d'un guide d'onde Périodique" de S. Kuznetsov. En 2007, N. Ryskin et al. avaient prouvé que ce modèle pouvait convenablement s'appliquer aux TOP à cavités couplées dans le cadre d'une application à une dimension du modèle. Lors de cette thèse, nous avons démontré, via le développement d'un code à une dimension (HelL-1D), que le modèle discret s'applique convenablement aux TOP à hélice. L'implémentation de ce modèle, dans un code à deux dimensions (HelL-2D) a, elle aussi, été effectuée. Enfin, nous avons développé une méthode permettant de contrôler de manière quantitative, dans le modèle discret, les phénomènes de réflexions aux extrémités de la ligne à retard, qui peuvent jouer un rôle important dans la stabilité de l'instrument. / This Ph.D. work deals with the time domain modeling and simulation of the electron beam/wave interaction in the slow-wave structure of a helix traveling-wave tube. Since a TWT is a device of which the geometry is oversized then the commercial software based on non-stationary general models needs so much computational resources that it cannot be used for design activities. During this Ph.D., we focused on the so called Kuznetsov's "discrete model of excitation of a periodic waveguide" which is a specialized model of beam/wave interaction in TWT. By 2007, N. Ryskin et al., showed that this model could conveniently apply to TWT with coupled cavities structure in one dimension. During this thesis, we first demonstrated that the discrete model could also apply to helix TWT with a sufficient (1%) accuracy via the development of a one-dimensional software called HelL-1D. We also implemented the discrete model for helix TWT in two dimensions (HelL-2D code). Finally, we developed a method, which is an extension of the discrete model, and which permits to take into account quantitatively the reflection phenomena at the terminations of a slow-wave structure in this model. This last study was very important since the stability of TWT strongly depends on this parameter.