Download or read book Frequency and Pulse Length Scaling of RF Breakdown in Accelerator Structures written by and published by . This book was released on 2002 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The plasma spot model predicts that small areas of plasma on the order of 10 microns in diameter form in regions of intense electric field near the iris tips of accelerator structures. These plasma spots act as a dc current source, injecting both electrons and ions into the rf field. The model suggests that an observable breakdown event will occur when electrons, extracted from the spot and accelerated, absorb energy faster than it can be supplied by the rf source. The resulting field collapse, which can occur during processing as the gradient is increased, is not an ultimate limit on accelerating gradient. It is conjectured that surface melting, due to electron back-bombardment at the emitting site, leads to a pseudospark-like discharge which limits the gradient and can produce massive surface damage. Using a statistical model, the dependence on frequency and pulse length of the probability of triggering a plasma spot is examined.
Download or read book Rf Breakdown Tests of Mm wave Metallic Accelerating Structures written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Here, we are exploring the physics and frequency-scaling of vacuum rf breakdowns at sub-THz frequencies. We present the experimental results of rf tests performed in metallic mm-wave accelerating structures. These experiments were carried out at the facility for advanced accelerator experimental tests (FACET) at the SLAC National Accelerator Laboratory. The rf fields were excited by the FACET ultrarelativistic electron beam. We compared the performances of metal structures made with copper and stainless steel. The rf frequency of the fundamental accelerating mode, propagating in the structures at the speed of light, varies from 115 to 140 GHz. The traveling wave structures are 0.1 m long and composed of 125 coupled cavities each. We determined the peak electric field and pulse length where the structures were not damaged by rf breakdowns. We calculated the electric and magnetic field correlated with the rf breakdowns using the FACET bunch parameters. The wakefields were calculated by a frequency domain method using periodic eigensolutions. Such a method takes into account wall losses and is applicable to a large variety of geometries. The maximum achieved accelerating gradient is 0.3 GV/m with a peak surface electric field of 1.5 GV/m and a pulse length of about 2.4 ns.
Download or read book RF Breakdown in Accelerator Structures written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma spots are known to form at field emission sites in regions of high dc or rf electric field. Several mechanisms for the formation of plasma spots in an rf field have been proposed, and one such mechanism which fits experimental data is presented in this paper. However, a plasma spot by itself does not produce breakdown. A single plasma spot, with a lifetime on the order of 30 ns, extracts only a negligible amount of energy from the rf field. The evidence for its existence is a small crater, on the order of 10 [mu]m in diameter, left behind on the surface. In this paper we present a model in which plasma spots act as a trigger to produce surface melting on a macroscopic scale (≈ 0.1 mm2). Once surface melting occurs, a plasma that is capable of emitting several kiloamperes of electrons can form over the molten region. A key observation that must be explained by any theory of breakdown is that the probability of breakdown is independent of time within the rf pulse breakdown is just as likely to occur at the beginning of the pulse as toward the end. In the model presented here, the conditions for breakdown develop over many pulses until a critical threshold for breakdown is reached.
Download or read book RF Breakdown in High Frequency Accelerators written by and published by . This book was released on 2004 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: RF breakdown in high-frequency accelerators appears to limit the maximum achievable gradient as well as the reliability of such devices. Experimental results from high power tests, obtained mostly in the framework of the NLC/GLC project at 11 GHz and from the CLIC study at 30 GHz, will be used to illustrate the important issues. The dependence of the breakdown phenomena on rf pulse length, operating frequency and fabrication material will be described. Since reliability is extremely important for large scale accelerators such as a linear collider, the measurements of breakdown rate as a function of the operating gradient will be highlighted.
Download or read book Rf Breakdown Measurements in Electron Beam Driven 200 GHz Copper and Copper silver Accelerating Structures written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study explores the physics of vacuum rf breakdowns in subterahertz high-gradient traveling-wave accelerating structures. We present the experimental results of rf tests of 200 GHz metallic accelerating structures, made of copper and copper-silver. These experiments were carried out at the Facility for Advanced Accelerator Experimental Tests (FACET) at the SLAC National Accelerator Laboratory. The rf fields were excited by the FACET ultrarelativistic electron beam. The traveling-wave structure is an open geometry, 10 cm long, composed of two halves separated by a gap. The rf frequency of the fundamental accelerating mode depends on the gap size and can be changed from 160 to 235 GHz. When the beam travels off axis, a deflecting field is induced in addition to the longitudinal field. We measure the deflecting forces by observing the displacement of the electron bunch and use this measurement to verify the expected accelerating gradient. Furthermore, we present the first quantitative measurement of rf breakdown rates in 200 GHz metallic accelerating structures. The breakdown rate of the copper structure is 10-2 per pulse, with a peak surface electric field of 500 MV/m and a rf pulse length of 0.3 ns, which at a relatively large gap of 1.5 mm, or one wavelength, corresponds to an accelerating gradient of 56 MV/m. For the same breakdown rate, the copper-silver structure has a peak electric field of 320 MV/m at a pulse length of 0.5 ns. For a gap of 1.1 mm, or 0.74 wavelengths, this corresponds to an accelerating gradient of 50 MV/m.
Download or read book High Gradient RF Breakdown Studies written by Lisa Leanne Laurent and published by . This book was released on 2002 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rf Breakdown Studies in Room Temperature Electron Linac Structures written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper is an overall review of studies carried out by the authors and some of their colleagues on RF breakdown, Field Emission and RF processing in room temperature electron linac structure. The motivation behind this work is twofold: in a fundamental way, to contribute to the understanding of the RF breakdown phenomenon, and as an application, to determine the maximum electric field gradient that can be obtained and used safely in future e/sup +-/ linear colliders. Indeed, the next generation of these machines will have to reach into the TeV (1012 eV) energy range, and the accelerating gradient will be to be of the crucial parameters affecting their design, construction and cost. For a specified total energy, the gradient sets the accelerator length, and once the RF structure, frequency and pulse repetition rate are selected, it also determines the peak and average power consumption. These three quantities are at the heart of the ultimate realizability and cost of these accelerators. 24 refs., 19 figs., 4 tabs.
Download or read book Frontiers Of Accelerator Technology Proceedings Of The Joint Us cern japan International School written by Melvin Month and published by World Scientific. This book was released on 1999-03-23 with total page 875 pages. Available in PDF, EPUB and Kindle. Book excerpt: The motivation to conceive and build accelerators comes from a most fundamental need of man — to understand and control the world around us. With beams and their associated accelerators, scientists and engineers can gain understanding of the nature of matter and modify matter, which is not possible by other means. The areas already influenced by the developments in accelerator technology are high energy and nuclear physics, atomic and molecular physics, condensed matter physics and the biological sciences. There are also a growing number of applications in medicine and industry.This book summarizes all the currently available knowledge on the rf technology driving the development of particle beams for science, medicine and industry. It is a unique collection of information on this technology.
Download or read book European Particle Accelerator Conference Epac 94 In 3 Volumes written by Christine Petit-jean-genaz and published by World Scientific. This book was released on 1994-11-26 with total page 2968 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings aim to provide a comprehensive overview of research, technology and applications in the field of accelerators. Contributions from the entire field of accelerators are presented, including low and high energy machines, and medical and industrial accelerators.
Download or read book Handbook Of Accelerator Physics And Engineering Third Edition written by Alexander Wu Chao and published by World Scientific. This book was released on 2023-02-02 with total page 960 pages. Available in PDF, EPUB and Kindle. Book excerpt: Edited by internationally recognized authorities in the field, this expanded and updated new edition of the bestselling Handbook, containing many new articles, is aimed at the design and operation of modern particle accelerators. It is intended as a vade mecum for professional engineers and physicists engaged in these subjects. With a collection of more than 2000 equations, 300 illustrations and 500 graphs and tables, here one will find, in addition to common formulae of previous compilations, hard to find, specialized formulae, recipes and material data pooled from the lifetime experience of many of the world's most able practioners of the art and science of accelerators.The seven chapters include both theoretical and practical matters as well as an extensive glossary of accelerator types. Chapters on beam dynamics and electromagnetic and nuclear interactions deal with linear and nonlinear single particle and collective effects including spin motion, beam-environment, beam-beam, beam-electron, beam-ion and intrabeam interactions. The impedance concept and related calculations are dealt with at length as are the instabilities due to the various interactions mentioned. A chapter on operational considerations including discussions on the assessment and correction of orbit and optics errors, realtime feedbacks, generation of short photon pulses, bunch compression, phase-space exchange, tuning of normal and superconducting linacs, energy recovery linacs, free electron lasers, cryogenic vacuum systems, steady state microbuching, cooling, space-charge compensation, brightness of light sources, collider luminosity optimization and collision schemes, machine learning, multiple frequency rf systems, FEL seeding, ultrafast electron diffraction, and Gamma Factory. Chapters on mechanical and electrical considerations present material data and important aspects of component design including heat transfer and refrigeration. Hardware systems for particle sources, feedback systems, confinement, including undulators, and acceleration (both normal and superconducting) receive detailed treatment in a sub-systems chapter, beam measurement and apparatus being treated therein as well.A detailed name and subject index is provided together with reliable references to the literature where the most detailed information available on all subjects treated can be found.
Download or read book High Energy Density and High Power RF written by David K. Abe and published by Springer Science & Business Media. This book was released on 2006-01-04 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the seventh in a series of international workshops on high-power and high-energy density microwave devices for accelerator, plasma physics, and defense applications. The scope of this workshop included accelerators for high energy physics, plasma heating and current drive in controlled thermonuclear fusion research, radar and directed energy/high power microwave systems, THz sources and technologies, and advanced 2D/3D computational tool development.
Download or read book Effect of RF Parameters on Breakdown Limits in High Vacuum X Band Structures written by and published by . This book was released on 2003 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: RF breakdown is one of the major factors determining performance of high power rf components and rf sources. RF breakdown limits working power and produces irreversible surface damage. The breakdown limit depends on the rf circuit, structure geometry, and rf frequency. It is also a function of the input power, pulse width, and surface electric and magnetic fields. In this paper we discuss multi-megawatt operation of X-band rf structures at pulse width on the order of one microsecond. These structures are used in rf systems of high gradient accelerators. Recent experiments at Stanford Linear Accelerator Center (SLAC) have explored the functional dependence of breakdown limit on input power and pulse width. The experimental data covered accelerating structures and waveguides. Another breakdown limit of accelerating structures was associated with high magnetic fields found in waveguide-to-structure couplers. To understand and quantify these limits we simulated 3D structures with the electrodynamics code Ansoft HFSS and the Particle-In-Cell code MAGIC3D. Results of these simulations together with experimental data will be discussed in this paper.
Download or read book EPAC 92 written by H. Henke and published by Atlantica Séguier Frontières. This book was released on 1992 with total page 910 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the 1999 Particle Accelerator Conference written by and published by . This book was released on 1999 with total page 882 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Science and Technology of Particle Accelerators written by Rob Appleby and published by CRC Press. This book was released on 2020-12-28 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Science and Technology of Particle Accelerators provides an accessible introduction to the field, and is suitable for advanced undergraduates, graduate students, and academics, as well as professionals in national laboratories and facilities, industry, and medicine who are designing or using particle accelerators. Providing integrated coverage of accelerator science and technology, this book presents the fundamental concepts alongside detailed engineering discussions and extensive practical guidance, including many numerical examples. For each topic, the authors provide a description of the physical principles, a guide to the practical application of those principles, and a discussion of how to design the components that allow the application to be realised. Features: Written by an interdisciplinary and highly respected team of physicists and engineers from the Cockcroft Institute of Accelerator Science and Technology in the UK Accessible style, with many numerical examples Contains an extensive set of problems, with fully worked solutions available Rob Appleby is an academic member of staff at the University of Manchester, and Chief Examiner in the Department of Physics and Astronomy. Graeme Burt is an academic member of staff at the University of Lancaster, and previous Director of Education at the Cockcroft Institute. James Clarke is head of Science Division in the Accelerator Science and Technology Centre at STFC Daresbury Laboratory. Hywel Owen is an academic member of staff at the University of Manchester, and Director of Education at the Cockcroft Institute. All authors are researchers within the Cockcroft Institute of Accelerator Science and Technology and have extensive experience in the design and construction of particle accelerators, including particle colliders, synchrotron radiation sources, free electron lasers, and medical and industrial accelerator systems.
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 Localization of RF Breakdown in Copper RF Structure by the Use of Acoustic Sensors written by F. Le Pimpec and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: X-band accelerator structures meeting the Next Linear Collider (NLC) design requirements have been found to suffer damage due to Radio Frequency (RF) breakdown when processed to high gradients. Improved understanding of these breakdown events is desirable for the development of structure designs, fabrication procedures, and processing techniques that minimize structure damage. Acoustic sensors attached to an accelerator structure can detect both normal and breakdown RF pulses. Using an array of acoustic sensors, we have been able to pinpoint both the cell and azimuth location of individual breakdown events. This allows studies of breakdown in time and in space, so that underlying causes can be determined. This technique provided a significant understanding of breakdown in the structure input coupler.
