Download or read book Beam Propagation Study Stabilization of the Resistive Hose Instability in Intense Electron Beams written by R. J. Adler and published by . This book was released on 1984 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of experiments has been performed to investigate the effect of unidirectional beam particle rotation on the resistive hose instability. Using the 4 MV, 100 kA, IBEX accelerator in a foil diode configuration, hose growth for hollow, partially hollow, and non-rotating Bennett profile beams was investigated. We found that partially hollow, rotating beams were most stable. In particular, they were more stable than non-rotating Bennett profile beams both in terms of the growth rate in per cm and in the growth per betatron wavelength. The observed reduction in instability growth rate per betatron wavelength over Bennett profile beams was a factor of 2.5. Stable propagation for>6 betation wavelength (the full experiment length) was observed in some shots where the beam was well aligned. Broadened return current profiles and long plasma decay times were also observed, consistent with our present understanding of high current mode propagation.
Download or read book Theory of the Resistive Hose Instability in Relativistic Electron Beams written by Han S. Uhm and published by . This book was released on 1979 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Vlasov-Maxwell theory of the resistive hose instability is developed, for an infinitely long relativistic electron beam propagating parallel to an applied axial magnetic field. Complete space charge neutralization by the ambient plasma, and paraxial flow (p(z)2” p(r) 2 + p(theta)2) are assumed. The analysis is performed for rigid-rotor and cold laminar flow equilibria. An integro-differential eigenvalue equation is obtained for the general case, and is reduced to an ordinary differential equation in either the cold laminar flow limit or the case of a square beam density profile. Using a variational technique, an approximate dispersion relation is found for arbitrary density profile, and evaluated in closed form for either the Bennett or square profile. Stability properties are illustrated and discussed in detail for a square profile, including the influence of the applied magnetic field (stabilizing), proximity to a conducting guide (stabilizing), and partial current neutralization (destabilizing). (Author).
Download or read book Resistive Hose Instability in a Dichromatic Electron Beam written by and published by . This book was released on 1984 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stability properties of the resistive hose instability are investigated for a self-pinched dichromatic electron beam propagating through a collisional plasma channel. The equilibrium and stability analysis is carried out for the electron distribution function in which beam electrons have two energy components. The beam density is assumed to be a Bennett profile. A closed algebraic dispersion relation of the resistive hose instability is obtained for a dichromatic beam, by making use of the energy group model. Numerical investigation of the dispersion relation is carried out for a ultra- relativistic electron beam. Unstable growth of the resistive hose instability along the beam frame coordinate is calculated. For an appropriate choice of the physical parameters, it is shown that the growth rate of instability in a dichromatic beam can be one third of that in a monochromatic beam, thereby tremendously increasing the beam pulse length for a stable propagation.
Download or read book Propagation of Low Gamma Ion Beams The Resistive Hose Instability written by R. Leon Feinstein and published by . This book was released on 1980 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this report on the propagation of low-gamma ion beams, we explore the resistive hose instability with longitudinal velocity-spread. For energies of interest, the theoretical models of electron beam propagation, cannot be directly applied to ions because of their low relativistic gamma (gamma) factors. For example, for kinetic energy equal to 50 MeV, gamma is = to or about 99. for electrons compared to gamma is = to or about 1.05 for protons. If the beam propagates in the longitudinal direction (along the z-axis), the effective inertial mass of the beam particles in the z-direction is given approximately by gamma 3 cubed m, where m is the particle rest mass. This suggests that light ions are considerably more susceptible to longitudinal acceleration than electrons of equivalent kinetic energy; the longitudinal particle-motion cannot be ignored as in the electron case. This adds a new dimension to ion beam propagation. The consequences of the longitudinal motion on beam stability can divided into three categories: (1) Longitudinal spreading of the beam pulse due to longitudinal velocity-spread (longitudinal temperature); (2) Longitudinal mass (bunching) instability; and (3) Resistive hose instability with longitudinal velocity spread.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Beam Propagation Experimental Study written by R. J. Adler and published by . This book was released on 1983 with total page 295 pages. Available in PDF, EPUB and Kindle. Book excerpt: A program of extensively diagnosed experiments to investigate the physics of intense relativistic electron beam propagation in air has been performed using beam generators at the Air Force Weapons Laboratory. The primary objectives of his research were to measure the rate of erosion of the head of the beam, and to investigate resistive instabilities, such as the hose and hollowing modes, that limit the transport of beam energy over significant distances.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-11 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Multi Component Model of the Resistive Hose Instability written by William M. Sharp and published by . This book was released on 1982 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new model of beam dynamics is presented for treating the resistive hose instability in intense, self-pinched electron or ion beams. The beam is modeled as a superposition of rigid, independently-moving components with different radii. This multi-component model exhibits the localized resonances and other analytic properties of a Vlasov treatment. The new model is used to calculate the eigenfunctions and the dispersion relation for hose instability of an axially uniform beam propagating in a medium of specified conductivity profile with any specified return current. Wave growth is found to be significantly increased by return current or by a narrow conductivity profile. The results are compared to those of earlier models. (Author).
Download or read book Pinched Propagation of High Power Pulsed Electron Beams for Welding and Materials Processing Applications written by and published by . This book was released on 1994 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electron beams are used commercially as intense heating sources for welding and related materials processing applications. The beams used for welding operate continuously with energy up to 200 keV and current - 1 A. Because these beams are severely degraded by propagation in air over any substantial range, most present-day electron-beam welders require vacuum pumping and precision focusing, which has severely restricted utilization of the technology. Over the past few decades, a different class of electron-beam generators has been developed that produces pulsed beams with energies of several MeV, currents of 1 kA or more' radii as small as 1 mm, pulse lengths of tens of ns, and pulse repetition rates up to several kHz. We show here that beams of this type can propagate in ambient air, in a tightly pinched mode and with acceptable stability, over distances of a few tens of cm We determine the constraints on the choice of beam parameters, due mainly to the effects of gas scattering and the resistive instability. We show that stability can be enhanced, and the acceptable parameter range extended considerably, by using a narrow conducting pipe filled with air or another gas to guide the beam to the workpiece. Relativistic electron beam, Nordsieck, Welding, Material processing, Resistive hose instability.
Download or read book On the Convective Properties of the Resistive Hose Instability in an Intense Relativistic Electron Beam written by Y. Y. Lau and published by . This book was released on 1983 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: We examine the convective characteristics of the resistive hose instability of a charged particle beam propagating in weakly ionized gas. We use a model which includes a plasma return current and a constant rate of plasma electrical conductivity production by the beam. When the spread mass model is adopted, the hose instability is shown, in all cases, to be convective in the beam frame, with the amplifying disturbances propagating from the beam head toward the beam tail, regardless of the amount of return current. The minimum speed of propagation for the amplifying disturbance is typically 1/3 to 1/2 of the group velocity associated with the maximum amplification rate. The implications of this result are explored.
Download or read book Fast Transverse Beam Instability Caused by Electron Cloud Trapped in Combined Function Magnets written by Sergey A. Antipov and published by Springer. This book was released on 2018-11-01 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents profound insights into the origins and dynamics of beam instabilities using both experimental observations and numerical simulations. When the Recycler Ring, a high-intensity proton beam accelerator at Fermi National Accelerator Laboratory, was commissioned, it became evident that the Recycler beam experiences a very fast instability of unknown nature. This instability was so fast that the existing dampers were ineffective at suppressing it. The nature of this phenomenon, alongside several other poorly understood features of the beam, became one of the biggest puzzles in the accelerator community. The author investigated a hypothesis that the instability arises from an interaction with a dense cloud of electrons accompanying the proton beam. He studied the phenomena experimentally by comparing the dynamics of stable and unstable beams, by numerically simulating the build-up of the electron cloud and its interaction with the beam, and by constructing an analytical model of an electron cloud-driven instability with the electrons trapped in combined-function dipole magnets. He has devised a method to stabilize the beam by a clearing bunch, which conclusively revealed that the instability is caused by the electron cloud, trapped in a strong magnetic field. Finally, he conducted measurements of the microwave propagation through a single dipole magnet. These measurements have confirmed the presence of the electron cloud in combined-function magnets.
Download or read book High Current Beam Hollowing Instability Study written by C. A. Ekdahl and published by . This book was released on 1985 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: High current relativistic electron beams propagating in air are subject to a variety of macroscopic resistive instabilities, including hollowing, hose, and filamentation. Although the hose instability typically dominates experiments, computer simulations indicate that hollowing is potentially very disruptive to fast current risetime beams, especially at low air density. There have, been at least three experiments which exhibited the hollowing instability clearly. Results from the last of these, performed using the 4 MeV, 70 kA IBEX beam generator, are analysed. The instability occurs routinely in computer simulations for beam currents above 17 kA and risetimes less than a few ns in full density air, and over broader parameter ranges at reduced air densities. It develops rapidly in the beam nose and is highly disruptive. Although emittance tailoring and electron energy spread can raise the threshold for the onset of hollowing, the stability of high current beams against hollowing can be assured only by maintaining a sufficiently long current risetime. A series of three high current beam experiments have been performed to confirm this theoretical picture of the hollowing instability.
Download or read book Physics of Intensity Dependent Beam Instabilities written by King-Yuen Ng and published by World Scientific. This book was released on 2006 with total page 795 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive treatment of intensity dependent particle beam instabilities in accelerating rings. Written for researchers, the material is also suitable for use as a textbook in an advanced graduate course for students studying accelerator physics. The presentation starts with a brief review of the basic concept of wake potentials and coupling impedances in the vacuum chamber followed by a discussion on static and dynamic solutions of their effects on the particle beams. Special emphasis is placed separately on proton and electron machines. Other special topics of interest covered include Landau damping, BalakinOCoNovokhatskyOCoSmirnov damping, Sacherer''s integral equations, Landau cavity, saw-tooth instability, Robinson stability criteria, beam loading, transition crossing, two-stream instabilities, and collective instability issues of isochronous rings. After the formulation of an instability, readers are provided a thorough description of one or more experimental observations together with a discussion of the cures for the instability. Although the book is theory oriented, the use of mathematics has been minimized. The presentation is intended to be rigorous and self-contained with nearly all the formulas and equations derived."
Download or read book Physics of Nonneutral Plasmas written by Davidson and published by Allied Publishers. This book was released on 1990 with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fusion Energy Update written by and published by . This book was released on 1980 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Of Nonneutral Plasmas written by Ronald C Davidson and published by World Scientific Publishing Company. This book was released on 2001-10-22 with total page 755 pages. Available in PDF, EPUB and Kindle. Book excerpt: A nonneutral plasma is a many-body collection of charged particles in which there is not overall charge neutrality. The diverse areas of application of nonneutral plasmas include: precision atomic clocks, trapping of antimatter plasmas and antihydrogen production, quantum computers, nonlinear vortex dynamics and fundamental transport processes in trapped nonneutral plasmas, strongly-coupled one-component plasmas and Coulomb crystals, coherent radiation generation in free electron devices, such as free electron lasers, magnetrons and cyclotron masers, and intense charged particle beam propagation in periodic focusing accelerators and transport systems, to mention a few examples. Physics of Nonneutral Plasmas is a graduate-level text — complete with 138 assigned problems and the results from several classic experiments — which covers a broad range of topics related to the fundamental properties of collective processes and nonlinear dynamics of one-component and multispecies charged particle systems in which there is not overall charge neutrality. The subject matter is treated systematically from first principles, using a unified theoretical approach, and the emphasis is on the development of basic concepts that illustrate the underlying physical processes in circumstances where intense self fields play a major role in determining the evolution of the system. The theoretical analysis includes the full influence of dc space charge effects on detailed equilibrium, stability and transport properties. The statistical models used to describe the properties of nonneutral plasmas are based on the nonlinear Vlasov-Maxwell equations, the macroscopic fluid-Maxwell equations, or the Klimontovich-Maxwell equations, as appropriate, and extensive use is made of theoretical techniques developed in the description of multispecies electrically-neutral plasmas, as well as established techniques in classical mechanics, electrodynamics and statistical physics.Physics of Nonneutral Plasmas emphasizes basic physics principles, and the thorough presentation style is intended to have a lasting appeal to graduate students and researchers alike. Because of the advanced theoretical techniques developed for describing one-component charged particle systems, this book serves as a useful companion volume to Physics of Intense Charged Particle Beams in High Energy Accelerators by Ronald C Davidson and Hong Qin.
Download or read book Energy in Physics War and Peace written by Hans Mark and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: Writing even in overview of more than a half-century of professional life of a giant of twentieth century science and technology such as Edward Teller is a daunting task. We ask in advance the reader's pardon for passing over quickly or omitting entirely aspects of Teller's life and work which may seem of major significance but which we, due to differences of perspective or knowledge, speak too little or not at all. We refer those interested in greater depth to the excellent biography by Stanley Blumberg and Gwen Owens, The Life and Times of Edward Teller, and we have (with his permission) printed Professor Eugene Wigner's An Appreciation On the 60th Birthday of Edward Teller immediately after this foreword, so that the reader may consider the perspective of one of Teller's most illustrious contemporaries more than two decades ago. Edward Teller was born in Budapest, Hungary on January 15,1908. While his childhood was spent in the twilight of the Victorian age and its abrupt conclusion in the Great War and his youth in its especially turbulent after math in central Europe, he doesn't bear visible scars from it.
