Download or read book Sparking Limits Cavity Loading and Beam Breakup Instability Associated with High current Rf Linacs written by and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The limitations on high-current rf linacs due to gap sparking, cavity loading, and the beam breakup instability are studied. It appears possible to achieve cavity accelerating gradients as high as 35 MV/m without sparking. Furthermore, a linear analysis, as well as self-consistent particle simulations of a multipulsed 10 kA beam, indicated that only a negligible small fraction of energy is radiated into nonfundamental cavity modes. Finally, the beam breakup instability is analyzed and found to be able to magnify initial radial perturbations by a factor of no more than about 20 during the beam transit time through a 1 GeV accelerator.
Download or read book SPARKING LIMITS CAVITY LOADING AND BEAM BREAKUP INSTABILITY ASSOCIATEDWITH HIGH CURRENT RF LINACS written by R. J. Faehl and published by . This book was released on 1982 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1983 with total page 1252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Publications of Los Alamos Research written by Los Alamos National Laboratory and published by . This book was released on 1983 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1982 with total page 1744 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Beam Breakup Instability in a Recirculating Linac Caused by a Quadrupole Mode written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Following the successful demonstration of energy recovery in a recirculating linac with superconducting cavities at the Jefferson Lab FEL[1], several ambitious electron accelerator projects have recently been proposed or are in study for either a light source or a collider based on this novel technology. These projects all intend to utilize a high quality linac electron beam generated with an average beam current typically in the range of 100's of mA. As is well known, a recirculating linac suffers from a beam breakup instability of a regenerative type caused by a Higher Order Mode (HOM) in an accelerating cavity, which can have a very high Q (quality factor) when superconducting. The instability can degrade the beam quality significantly. We investigate one such beam breakup instability in a recirculating linac that could arise as a result of high Q quadrupole modes excited in the cavity. In a simple model we derive a relation which allows one to deduce the upper limit on tolerable Q ...
Download or read book Control of Beam Dynamics in High Energy Induction Linacs written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Advent of laser-ion-guiding in the Advanced test Accelerator along with the development of accelerator cavities optimized with respect to beam breakup coupling impedence now make it possible to consider a new class of high current, high emergy linear induction accelerators. The control of the beam breakup and other instabilities by laser guiding and by various magnetic focusing schemes will be discussed along with the scaling laws for the design of such machines to minimize the growth of the beam breakup instability. Many linacs, particularly induction linacs are limited in performance by the beam breakup (BBU) instability. The instability is found in two forms. In the first form the accelerating cavities communicate with one another through interaction with the beam and through propagation of cavity fields through the accelerator structure. In the second form which is the more virulent of the two, the cavities couple to each other only through their interactions with the beam. It is this second form of PPU that will be discussed in this paper.
Download or read book Physics Briefs written by and published by . This book was released on 1982 with total page 1126 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book INIS Atomindex written by and published by . This book was released on 1983 with total page 842 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation of Beam Breakup in the Jefferson Laboratory 10 KW FEL Upgrade Driver written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In recirculating accelerators, and in particular energy recovery linacs (ERLs), the maximum current has been limited by multipass, multibunch beam breakup (BBU), which occurs when the electron beam interacts with the higher-order modes (HOMs) of an accelerating cavity on the accelerating pass and again on the energy recovered pass. This effect is of particular concern in the design of modern high average current energy recovery accelerators utilizing superconducting RF technology. Experimental observations of the instability at the Jefferson Laboratory 10 kW Free-Electron Laser (FEL) are presented. Measurements of the threshold current for the instability are presented and compared to the predictions of several BBU simulation codes. With BBU posing a threat to high current beam operation in the FEL Driver, several suppression schemes were developed. These include direct damping of the dangerous HOMs and appropriately modifying the electron beam optics. Preliminary results of their effectiveness in raising the threshold current for stability are presented.
Download or read book Cumulative Beam Breakup in Radio frequency Linacs written by and published by . This book was released on 1990 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analytic model of cumulative beam breakup has been developed which is applicable to both low-velocity ion and high-energy electron linear accelerators. The model includes arbitrary velocity, acceleration, focusing, initial conditions, beam-cavity resonances, and variable cavity geometry and spacing along the accelerator. The model involves a continuum approximation'' in which the transverse kicks in momentum imparted by the cavities are smoothed over the length of the linac. The resulting equation of transverse motion is solved via the WKBJ method. Specific examples are discussed which correspond to limiting cases of the solution. 16 refs.
Download or read book Tools to Predict Beam Breakup in Recirculating Linacs written by and published by . This book was released on 2003 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important limitation on the maximum beam current in a recirculating linac is due to beam breakup caused by higher order modes (HOM) excited in the RF cavities. A HOM delivers a transverse kick to a beam bunch, the bunch on the next pass can then drive the HOM and cause it to grow until the beam is lost. Two codes, MATBBU1 and TDBBU2, have been written to estimate the threshold current for a set of HOMs and accelerator optics. The relative merits and limitations of each is discussed in detail.
Download or read book Multipass Beam Breakup in the CEBAF Superconducting Linac written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Beam breakup (BBU) instabilities in superconducting linacs are a significant issue due to the potentially high Q values of the cavity higher order modes (HOMs). The CEBAF accelerator, which employs high CW current and 5- pass recirculation through two superconducting linacs, poses unique instability problems. An experimental investigation of multipass BBU along with energy recovery has been completed using a single recirculation through the CEBAF injector linac. Experimental results are compared with computer simulation of multipass BBU.
Download or read book Operation of the CEBAF Linac with High Beam Loading written by and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The superconducting RF, CW CEBAF accelerator will use a pair of antiparallel 400 MeV linacs connected by recirculation arcs for nominal 4 GeV in five passes. Single-pass, high power testing of the first linac has been conducted during the months preceding the conference. The RF control system [1] has been designed to control cavity gradient and phase under a wide range of gradients and significant beam loading. At full beam current, accelerating gradient is approximately equal to accelerating voltage in the superconducting RF cavities. Even though the beam current during the high power testing is one-fifth of the full current, beam loading is substantial. Operational experience of the response of the RF system is presented. A tuning algorithm which compensates for beam loading effects has been developed and tested. Heavy beam loading, corresponding to five-pass operation, was studied by increasing the loaded Q of the cavities. A current modulation experiment addressed the issue of energy spread increase due to current fluctuations, and the effect of by-passed cavities on beam properties was investigated.
Download or read book Studies of Multipass Beam Breakup and Energy Recovery Using the CEBAF Injector Linac written by and published by . This book was released on 1993 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Beam breakup (BBU) instabilities in superconducting linacs are a significant issue due to the potentially high Q values of the cavity higher order modes (HOMs). The CEBAF accelerator, which employs high CW current and 5-pass recirculation through two superconducting linacs, poses unique instability problems. An experimental investigation of multipass BBU along with energy recovery has been completed using a single recirculation through the CEBAF injector linac. Experimental results are compared with computer simulation of multipass BBU.
Download or read book Calculating Beam Breakup in Superconducting Linear Accelerators written by and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As the intensity of a particle beam passing through a linear accelerator is raised, interactions between particles play an increasingly prominent role in determining the overall dynamics of the beam. These many body effects, known collectively as beam breakup, tend to degrade the quality of the transported beam, and hence they must be calculated to accurately predict the evolution of the beam as it traverses the accelerator. Several codes which compute various collective effects have been developed and used to simulate the dynamics of beams passing through superconducting accelerator structures. All the codes use the same basic algorithm: the beam is tracked through elements giving the focusing forces on the particles, and at the appropriate locations in the linac, localized forces are impressed on the particles which model the electromagnetic interactions. Here, a difficulty is that the usual ''Coulomb'' interaction between particles is changed by the electromagnetic environment of the accelerator. By such calculations it has been shown that recirculating linear accelerators such as the one being built at the Continuous Electron Beam Accelerator Facility (CEBAF) should remain stable against multipass beam breakup instability as long as the average current does not exceed about 20 mA, that the beam quality at CEBAF will be degraded when the single bunch charge approaches 109 electrons, and that the beam quality of superconducting linacs that are optimized for high current transport begins to decrease at around 101° electrons per bunch. The latter result is of interest to individuals who would use superconducting linacs as beam sources for free electron lasers or for superconducting colliders for high energy physics research.
Download or read book Chromaticity of the Lattice and Beam Stability in Energy recovery Linacs written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Energy recovery linacs (ERLs) are an emerging generation of accelerators promising to revolutionize the fields of high-energy physics and photon sciences. These accelerators combine the advantages of linear accelerators with that of storage rings, and hold the promise of delivering electron beams of unprecedented power and quality. Use of superconducting radio-frequency (SRF) cavities converts ERLs into nearly perfect 'perpetuum mobile' accelerators, wherein the beam is accelerated to a desirable energy, used, and then gives the energy back to the RF field. One potential weakness of these devices is transverse beam break-up instability that could severely limit the available beam current. In this paper, I present a method of suppressing these dangerous effects using a natural phenomenon in the accelerators, viz., the chromaticity of the transverse motion.
