Download or read book Processing Studies of X Band Accelerator Structures at the NLCTA written by and published by . This book was released on 2001 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: RF processing studies of 1.8-m X-band (11.4 GHz) traveling wave structures at the Next Linear Collider Test Accelerator (NLCTA) have revealed breakdown-related damage at gradients lower than expected from earlier tests with standing wave and shorter, lower group velocity traveling wave structures. To understand this difference, a series of structures with different group velocities and lengths are being processed. In parallel, efforts are being made to improve processing procedures and to reduce structure contaminants and absorbed gases. This paper presents results from these studies.

Download or read book RF Processing of X Band Accelerator Structures at the NLCTA written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: During the initial phase of operation, the linacs of the Next Linear Collider (NLC) will contain roughly 5,000 X-Band accelerator structures that will accelerate beams of electrons and positrons to 250 GeV. These structures will nominally operate at an unloaded gradient of 72 MV/m. As part of the NLC R and D program, several prototype structures have been built and operated at the Next Linear Collider Test Accelerator (NLCTA) at SLAC. Here, the effect of high gradient operation on the structure performance has been studied. Significant progress was made during the past year after the NLCTA power sources were upgraded to reliably produce the required NLC power levels and beyond. This paper describes the structures, the processing methodology and the observed effects of high gradient operation.

Download or read book Studies of Breakdown in High Gradient X Band Accelerator Structures Using Acoustic Emission written by and published by . This book was released on 2002 with total page 4 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 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 [1]. Acoustic emission sensors attached to an accelerator structure can detect both nominal and breakdown RF pulses [2]. 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 time and position sequences so that underlying causes can be determined. The technique provided a significant advance in studies of breakdown in the structure input coupler. In this paper we present acoustic emission sensor data and analysis from the breakdown studies in several x-band accelerator structures.

Download or read book Investigations on rf breakdown phenomenon in high gradient accelerating structures written by Jiahang Shao and published by Springer. This book was released on 2018-01-19 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book mainly focuses on the experimental research of rf breakdown and field emission with novel methods, including triggering rf breakdown with high intensity laser and pin-shaped cathodes as well as locating field emitters with a high resolution in-situ imaging system. With these methods, this book has analyzed the power flow between cells during rf breakdown, observed the evolution of field emission during rf conditioning and the dependence of field emission on stored energy, and studied the field emitter distribution and origination. The research findings greatly expand the understanding of rf breakdown and field emission, which will in turn benefit future study into electron sources, particle accelerators, and high gradient rf devices in general.

Download or read book High Gradient Experiments on NLCTA Accelerator Structures written by and published by . This book was released on 1996 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents new results of high-gradient studies performed on a 1.8 m traveling-wave accelerator section with detuned high-order deflecting modes. This structure was designed initially for studies of detuned structures and will be installed in the Next Linear Collider Test Accelerator (NLCTA). The paper describes the test set-up in the Accelerator Structure Test Area (ASTA) including electron gun, prebuncher, pre-accelerator, spectrometer, Faraday cups, 200 MW SLED-II power compression system, Magic-T type phase shifters and attenuators. Rf processing, detailed dark current analysis, radiation problems, and beam acceleration measurements are discussed.

Download or read book High Gradient Test of a Clamped Molybdenum Iris X Band Accelerator Structure at NLCTA written by S. Doebert and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Inspired by the very high gradients (150-195 MV/m) achieved at CERN in 30 GHz accelerator structures made with tungsten and molybdenum irises and operated with short (16 ns) rf pulses [1], an X-band (11.4 GHz) version of this structure design was built at CERN and tested at SLAC. The goals of this experiment were to provide frequency scaling data on high gradient phenomena at similar pulse lengths, and to measure the structure performance at the longer pulse lengths available at SLAC (the CLIC test facility, CTF II, could provide only 16 ns pulses for high power operation and 32 ns pulses for medium power operation). Earlier high gradient tests of 21 GHz to 39 GHz standing-wave, single cells, indicated no significant frequency dependence of the maximum obtainable surface field [2]. The X-band scaling test would check if this was true for travelling-wave, multi-cell structures as well. For the experiment, the CLIC group at CERN built a 30 cell accelerating structure that consisted of copper cells and molybdenum irises that were clamped together. The structure was mounted in a vacuum tank and installed in the Next Linear Collider Test Accelerator (NLCTA) beam line at SLAC where it was operated at high power for more than 700 hours.

Download or read book High Energy Density and High Power RF written by Steven H. Gold and published by American Inst. of Physics. This book was released on 2003-12-04 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the sixth in a series of international workshops on high-power and high-energy density microwave devices for accelerator, plasma physics, and defense applications. Past workshops were held in Dubna, Montauk, Hayama, Pajaro Dunes, and Snowbird. The theme is research and development of techniques to increase microwave energy density and peak power in active and passive microwave devices and components ranging from L-band to W-band. The scope of this workshop has now been broadened to include radar and high power microwave (HPM) systems, space exploration, neutron sources, and even plasma heating and current drive in controlled thermonuclear fusion research.

Download or read book Advanced Accelerator Concepts written by Christopher E. Clayton and published by American Inst. of Physics. This book was released on 2002-12-06 with total page 952 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 10th Workshop on Advanced Accelerator Concepts reviews the current progress in the rapidly growing field of advanced accelerators. This series of DOE-sponsored workshops attracts researchers who invent and explore the physics and technologies needed to generate, accelerate, and manipulate particles with plasmas, laser and particle beams, as well as RF and mm-waves. Applications include advanced radiation sources and high energy physics.

Download or read book Preliminary Study on Two Possible Bunch Compression Schemes at NLCTA written by and published by . This book was released on 2011 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, two possible bunch compression configurations are proposed and evaluated by numerical simulation in the Next Linear Collider Test Accelerator (NLCTA) at SLAC. A bunch compression ratio up to 20 could be achieved under a perfect condition, without consideration for the timing jitter and other error sources. The NLCTA is a test accelerator built at SLAC, which is approximately 42 meters long and composed of X-band acceleration structures. The main aim of building NLCTA is to develop and demonstrate the X-band rf acceleration technologies for the next generation linear collider, with a relatively high acceleration gradient between 50 MV/m and 100 MV/m. The current operation configuration of NLCTA features a thermionic-cathode electron gun at its starting point which generates an electron beam with an energy of 5 MeV. This is followed by a roughly 1.5 meter long X-band acceleration structure which boosts the electron beam energy to 60 MeV. Then there is a four-dipole magnetic chicane which is 6 meters long and provides a first order longitudinal dispersion of R56 = -73mm. Next the electron beam passes by several matching quadrupoles and can be accelerated further to 120 MeV through another one-meter-long X-band acceleration structure. After that, there are three small chicanes downstream, with a total first order longitudinal dispersion of R56 = -10mm. A sketch of the main components of NLCTA is shown in Figure 1, where the total length of this accelerator is 45 meters. Free Electron Lasers (FELs), proposed by J. Madey and demonstrated for the first time at Stanford University in 1970s [2] [3], use the lasing of relativistic electron beam traveling through a magnetic undulator, which can reach high power and can be widely tunable in wavelength. Linac based FEL source can provide sufficient brightness, and a short X-ray wavelength down to angstrom scale, which promises in supporting wide range of research experiments. In order to have an electron beam lasing coherently in an undulator, one needs a very bright beam in all three dimensions. In other words, one needs an electron beam with very short bunch length (high intensity), very small transverse emittance and very small energy spread. Most FELs currently being operated, commissioned, constructed or proposed are based on RF acceleration in a frequency range from L-band (1 GHz) to C-band (6 GHz). As RF frequency goes higher, wake fields effects tend to be much stronger and jitter tolerances are tighter. To demonstrate that X-band acceleration structures can be applied in constructing an FEL, one could perform bunch compression experiments at NLCTA as a first step, and investigate tolerances on timing jitter, misalignments etc. Another important point is to evaluate the transverse emittance growth in this bunch compression process. In the following sections, two possible bunch compression schemes are proposed to be tested at NLCTA. Elegant [4] 3-D simulation is performed to evaluate these two schemes, with wake fields, space charge and coherent synchrotron radiation (CSR) effects included. One million macro particles are adopted in the numerical simulations. The simulation starts with an electron beam of 20 pC at a beam energy of 5 MeV. The initial RMS bunch length is taken as 0.5 ps at such a low bunch charge, and the RMS energy spread is 5 x 10−3. The normalized transverse emittance is 1 mm.mrad.

Download or read book Studies on High precision Machining of Accelerator Disks of X band Structure for a Linear Collider written by Y. Higashi and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Final Report on Development and Testing of Advanced Accelerator Structures and Technologies at 11 424 GHz written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the final report on the research program?Development and Testing of Advanced Accelerator Structures and Technologies at 11.424 GHz,? which was carried out by the Naval Research Laboratory (NRL) under Interagency Agreement DE?AI02?01ER41170 with the Department of Energy. The period covered by this report is 15 July 2010? 14 July 2013. The program included two principal tasks. Task 1 involved a study of the key physics issues related to the use of high gradient dielectric-loaded accelerating (DLA) structures in rf linear accelerators and was carried out in collaboration with Argonne National Laboratory (ANL) and Euclid Techlabs LLC. Task 2 involved a study of high power active microwave pulse compressors and was carried out in collaboration with Omega-P, Inc. and the Institute of Applied Physics of the Russian Academy of Sciences in Nizhny Novgorod. The studies under Task 1 were focused on rf-induced multipactor and breakdown in externally driven DLA structures at the 200-ns timescale. Suppression of multipactor and breakdown are essential to the practical application of dielectric structures in rf linear accelerators. The structures that were studied were developed by ANL and Euclid Techlabs and their performance was evaluated at high power in the X-band Magnicon Laboratory at NRL. Three structures were designed, fabricated, and tested, and the results analyzed in the first two years of the program: a clamped quartz traveling-wave (TW) structure, a externally copper-coated TW structure, and an externally copper-coated dielectric standing-wave (SW) structure. These structures showed that rf breakdown could be largely eliminated by eliminating dielectric joints in the structures, but that the multipactor loading was omnipresent. In the third year of the program, the focus of the program was on multipactor suppression using a strong applied axial magnetic field, as proposed by Chang et al. [C. Chang et al., J. Appl. Phys. 110, 063304 (2011).], and a successful experiment was carried out that demonstrated suppression of multipactor in the uniform-field region of a TW DLA structure. However, in accordance with theory, the multipactor was enhanced in regions of the structure with lower values of axial magnetic field. Under Task 2, there were two two-month experimental runs at NRL that were used to characterize the performance of high power two-channel dual-mode active microwave pulse compressor configurations that used electron-beam triggered switch cavities. The pulse compressors were designed and fabricated by Omega-P, Inc. and the Russian Institute of Applied Physics and tested in the Magnicon Laboratory at NRL. These pulse compressors made use of an electron beam discharge from a cylindrical knife-edged Mo cathode coated with a CVD diamond film that was driven by a?100 kV, 100 ns high voltage pulse. The electron beam was used to change the resonant frequency of the switch cavities in order to create the output microwave pulse. The compressor channels included a TE01 input and output section and a TE02 energy storage cavity, followed by a switch assembly that controlled the coupling between the TE01 and TE02 modes. In the initial state, the switch cavity was in resonance, the reflection from the cavity was out of phase, and the mode conversion was only ~2-3%, allowing the energy storage cavity to fill. When the electron beam was discharged into the switch cavity, the cavity was shifted out of resonance, causing the phase of the reflection to change by ~[pi]. As a result of the change in the reflection phase, the mode coupling in the conical taper was greatly increased, and could approach ~100%, permitting the energy storage cavity to empty in one cavity round trip time of the TE02 mode to produce a high power output pulse. The second experiment runs demonstrated a 190 MW, ~20 ns compressed pulse at 25.7 gain and ~50% efficiency, using a 7.4 MW, 1?s drive pulse from the magnicon. The success of this experiment suggests ...

Download or read book Experimental Studies of W band Accelerator Structures at High Field written by Marc Edward Hill and published by . This book was released on 2000 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reviews of Accelerator Science and Technology written by Alex Chao and published by World Scientific. This book was released on 2012-02-20 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since their debut in the late 1920s, particle accelerators have evolved into a backbone for the development of science and technology in modern society. Of about 30,000 accelerators at work in the world today, a majority is for applications in industry (about 20,000 systems worldwide). There are two major categories of industrial applications: materials processing and treatment, and materials analysis. Materials processing and treatment includes ion implantation (semi-conductor materials, metals, ceramics, etc.) and electron beam irradiation (sterilization of medical devices, food pasteurization, treatment of carcasses and tires, cross-linking of polymers, cutting and welding, curing of composites, etc.). Materials analysis covers ion beam analysis (IBA), non-destructive detection using photons and neutrons, as well as accelerator mass spectrometry (AMS). All the products that are processed, treated and inspected using beams from particle accelerators are estimated to have a collective value of US$500 billion per annum worldwide. Accelerators are also applied for environment protection, such as purifying drinking water, treating waste water, disinfecting sewage sludge and removing pollutants from flue gases. Industrial accelerators continue to evolve, in terms of new applications, qualities and capabilities, and reduction of their costs. Breakthroughs are encountered whenever a new product is made, or an existing product becomes more cost effective. Their impact on our society continues to grow with the potential to address key issues in economics or the society of today. This volume contains fourteen articles, all authored by renowned scientists in their respective fields.

Download or read book Advances in X Band TW Accelerator Structures Operating in the 100 MV M Regime written by and published by . This book was released on 2012 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: A CERN-SLAC-KEK collaboration on high gradient X-band accelerator structure development for CLIC has been ongoing for three years. The major outcome has been the demonstration of stable 100 MV/m gradient operation of a number of CLIC prototype structures. These structures were fabricated using the technology developed from 1994 to 2004 for the GLC/NLC linear collider initiative. One of the goals has been to refine the essential parameters and fabrication procedures needed to realize such a high gradient routinely. Another goal has been to develop structures with stronger dipole mode damping than those for GLC/NLC. The latter requires that the surface temperature rise during the pulse be higher, which may increase the breakdown rate. One structure with heavy damping has been RF processed and another is nearly finished. The breakdown rates of these structures were found to be higher by two orders of magnitude compared to those with equivalent acceleration mode parameters but without the damping features. This paper presents these results together with some of the earlier results from non-damped structures.

Download or read book Reviews Of Accelerator Science And Technology Volume 4 Accelerator Applications In Industry And The Environment written by Alexander Wu Chao and published by World Scientific. This book was released on 2012-02-20 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since their debut in the late 1920s, particle accelerators have evolved into a backbone for the development of science and technology in modern society. Of about 30,000 accelerators at work in the world today, a majority is for applications in industry (about 20,000 systems worldwide).There are two major categories of industrial applications: materials processing and treatment, and materials analysis. Materials processing and treatment includes ion implantation (semi-conductor materials, metals, ceramics, etc.) and electron beam irradiation (sterilization of medical devices, food pasteurization, treatment of carcasses and tires, cross-linking of polymers, cutting and welding, curing of composites, etc.). Materials analysis covers ion beam analysis (IBA), non-destructive detection using photons and neutrons, as well as accelerator mass spectrometry (AMS). All the products that are processed, treated and inspected using beams from particle accelerators are estimated to have a collective value of US$500 billion per annum worldwide. Accelerators are also applied for environment protection, such as purifying drinking water, treating waste water, disinfecting sewage sludge and removing pollutants from flue gases.Industrial accelerators continue to evolve, in terms of new applications, qualities and capabilities, and reduction of their costs. Breakthroughs are encountered whenever a new product is made, or an existing product becomes more cost effective. Their impact on our society continues to grow with the potential to address key issues in economics or the society of today.This volume contains fourteen articles, all authored by renowned scientists in their respective fields.

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 Experimental Studies of Novel Accelerator Structures at 11 GHz and 17 GHz written by Brian James Munroe and published by . This book was released on 2015 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photonic band-gap (PBG) structures are promising candidates for electron accelerators capable of high-gradient operation because they have the inherent damping of high order modes required to avoid beam breakup due to instabilities. A key challenge for PBG structures is high-gradient operation without structure damage due to rf-field-induced breakdowns. This thesis reports theoretical results on the design of PBG structures and the generation of wakefields in such structures. It also reports experimental results on PBG structure breakdown testing at high power at both 11 and 17 GHz. A single-cell photonic band-gap (PBG) structure was designed with an inner row of elliptical rods (PBG-E) to reduce ohmic heating relative to a round-rod structure. The PBG-E structure was built and tested at high power at a 60 Hz repetition rate at X-Band (11.424 GHz) at the SLAC accelerator test stand, achieving a gradient of 128 MV/m at a breakdown probability of 3.6 x 10-3 per pulse per meter at a pulse length of 150 ns. The PBG-E structure showed major improvement in breakdown rate relative to a round-rod PBG structure designed at MIT and previously tested at SLAC. A test stand was designed and built at MIT for testing single-cell structures at 17.1 GHz, a frequency 50% higher than the SLAC frequency. This test stand provides comparable diagnostics to those used at SLAC, adding optical diagnostic access which can be used for open PBG structures. A conventional disc-loaded waveguide structure, MIT-DLWG, was tested at MIT at up to a 2 Hz repetition rate. This structure reached a maximum gradient of 87 MV/m at a breakdown probability of 1.19 x 10-1 per pulse per meter. A round-rod PBG structure, MIT-PBG-2, has also been tested at MIT at up to a 2 Hz repetition rate and 100 ns pulse length, demonstrating operation up to 89 MV/rn at a breakdown probability of 1.09 x 10-1 per pulse per meter. These test results show that a PBG structure can simultaneously operate at high gradients and low breakdown probability, while also providing wakefield damping. This makes PBG structures viable candidates for future collider applications.