Download or read book COAXIAL HOM COUPLER DESIGNS TESTED ON A SINGLE CELL NIOBIUM CAVITY written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Poster - Coaxial higher order mode (HOM) couplers have been developed for HERA cavities and are used in TESLA, SNS and JLab upgrade cavities. The principle of operation is the rejection of the fundamental mode by the tunable filter of the coupler and the transmission of the HOMs. It has been recognized recently that inappropriate thermal designs of the feed through for the pick-up probe of the HOM coupler will not sufficiently carry away the heat generated in the probe tip by the fundamental mode fields, causing a built-up of the heating of the niobium probe tip and subsequently, a deterioration of the cavity quality factor has been observed in CW operation. An improvement of the situation has been realized by a better thermal design of the feed through incorporating a sapphire rf window. An alternative is a modification of the coupler loop (?F?? part) with an extension towards the pick-up probe. This design has been tested on a single cell niobium cavity in comparison to a 'standard TESLA' configuration by measuring the Eacc behavior at 2 K. The measurements clearly indicate that the modified version of the coupler loop is thermally much more stable than the standard version.
Download or read book Coaxial HOM Coupler Designs Tested on a Single Cell Niobium Cavity written by Peter Kneisel and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Coaxial higher order mode (HOM) couplers have been developed for HERA cavities and are used in TESLA, SNS and JLab upgrade cavities. The principle of operation is the rejection of the fundamental mode by the tunable filter of the coupler and the transmission of the HOMs. It has been recognized recently that inappropriate thermal designs of the feedthrough for the pick-up probe of the HOM coupler will not sufficiently carry away the heat generated in the probe tip by the fundamental mode fields, causing a built-up of the heating of the niobium probe tip and subsequently, a deterioration of the cavity quality factor has been observed in CW operation. An improvement of the situation has been realized by a better thermal design of the feedthrough incorporating a sapphire rf window [1]. An alternative is a modification of the coupler loop (?F?? part) with an extension towards the pick-up probe. This design has been tested on a single cell niobium cavity in comparison to a ''standard TESLA'' configuration by measuring the Eacc behavior at 2 K. The measurements clearly indicate that the modified version of the coupler loop is thermally much more stable than the standard version.
Download or read book Testing of HOM Coupler Designs on a Single Cell Niobium Cavity written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Coaxial higher order mode (HOM) couplers were developed initially for HERA cavities and subsequently for TESLA cavities. They were adopted later for SNS and Jlab upgrade cavities. The principle of operation is the rejection of the fundamental mode by the tunable filter and the transmission of the HOMs. It has been recognized recently that for continuous wave or high duty factor applications of the TESLA coupler the output pick-up probe must stay superconducting in order to avoid its heating by the fundamental mode residual magnetic field leading to deterioration of the cavity quality factor. In addition, the thermal conduction of existing rf feedthrough designs is only marginally sufficient to keep even the niobium probe tip superconducting in cw operation. We have equipped a single-cell niobium cavity with the modified HOM couplers and tested the new designs by measuring Q vs Eacc behavior at 2 K for different feedthroughs and probe tip materials.
Download or read book RF Superconductivity written by Hasan Padamsee and published by John Wiley & Sons. This book was released on 2009-03-30 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the second book to RF Superconducting, written by one of the leading experts. The book provides fast and up-to-date access to the latest advances in the key technology for future accelerators. Experts as well as newcomers to the field will benefit from the discussion of progress in the basic science, technology as well as recent and forthcoming applications. Researchers in accelerator physics will also find much that is relevant to their discipline.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1990 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Progress on the Development of a Superconducting Connection for Niobium Cavities written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The availability of a superconducting connection between adjacent niobium radio-frequency (RF) cavities with the capability to carry up to 30 mT of the magnetic flux would be particularly of great benefit to layouts of long accelerators like the International Linear Collider (ILC). It would shorten the distances between structures and therefore the total length of an accelerator with the associated cost reductions. In addition, the superconducting connection would be ideal for a superstructure - two multi-cell cavities connected through a half wavelength long beam pipe providing the coupling. Two single-cell niobium cavities have been designed with Nb-1Zr flanges welded to one of the irises to allow a connection between them with a niobium gasket. A transition to the normal-conducting state of the connection due to the applied RF field causes a reduction of the cavities' quality factor. The cavity design will be presented in this contribution along with possible choices of materials for the joint.
Download or read book High Brightness Accelerators written by Anthony D. Hyder and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 812 pages. Available in PDF, EPUB and Kindle. Book excerpt: A NATO Advanced Study Institute (ASI) on High-Brightness Accelerators was held at the Atholl Palace Hotel, Pitlochry, Perthshire, Scotland, from July 13 through July 25, 1986. This publication is the Proceedings of the Institute. This ASI emphasized the basic physics and engineering of the rela tively new and fast-emerging field of high-brightness particle accelera tors. These machines are high- to very-high-current (amperes to hundreds of kiloamperes), modest-voltage (megavolt to tens of megavolts) devices, and as such are opposed to those historically used for high-energy physics studies (i.e., gigavolt and higher energies and rather low currents). The primary focus of the Institute was on the physics of the accelerator and the beam, including the dynamics, equilibria, and insta bilities of high-current beams near the space-charge limit; accelerator engineering techniques; and the applications of high-brightness beams in areas such as free-electron lasers, synchrotron-radiation sources, food processing, and heavy- and light-ion fusion. The Institute concentrated on bringing together several diverse but related communities which, we hope, benefited from this opportunity to interact: the North American activity in machine technology, engineer ing, and diagnostics with the strong European theoretical community; the basic beam physicists with the engineering technologists.
Download or read book EPAC96 Fifth European Particle Accelerator Conference written by and published by . This book was released on 1996 with total page 968 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New HOM Coupler Design for High Current SRF Cavity written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Damping higher order modes (HOMs) significantly to avoid beam instability is a challenge for the high current Energy Recovery Linac-based eRHIC at BNL. To avoid the overheating effect and high tuning sensitivity, current, a new band-stop HOM coupler is being designed at BNL. The new HOM coupler has a bandwidth of tens of MHz to reject the fundamental mode, which will avoid overheating due to fundamental frequency shifting because of cooling down. In addition, the S21 parameter of the band-pass filter is nearly flat from first higher order mode to 5 times the fundamental frequency. The simulation results showed that the new couplers effectively damp HOMs for the eRHIC cavity with enlarged beam tube diameter and 2 120{sup o} HOM couplers at each side of cavity. This paper presents the design of HOM coupler, HOM damping capacity for eRHIC cavity and prototype test results.
Download or read book Superconducting Prototype Cavities for the Spallation Neutron Source SNS Project written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Spallation Neutron Source project includes a superconducting linac section in the energy range from 186 MeV to 1000 MeV. For this energy range two types of cavities are needed with geometrical [beta] values of [beta] = 0.61 and [beta] = 0.81. An aggressive cavity prototyping program is being pursued at Jefferson Lab, which calls for fabricating and testing four [beta] = 0.61 cavities and two [beta] = 0.81 cavities. Both types consist of six cells made from high purity niobium and feature one HOM coupler on each beam pipe and a port for a high power coaxial input coupler. Three of the four [beta] = 0.61 cavities will be used for a cryomodule test in early 2002. At this time four medium beta cavities and one high beta cavity have been completed at JLab. The first tests on the [beta] = 0.61 and [beta] = 0.81 exceeded the design values for gradient and Q value: E[sub acc] = 10.1 MV/m and Q = 5 x 10[sup 9] at 2.1K for the [beta] = 0.61 and E[sub acc] = 12.3 MV/m and Q = 5 x 10[sup 9] at 2.1 K for the [beta] = 0.81. One of the medium beta cavities has been equipped with an integrated helium vessel and measurements of the static Lorentz force detuning have been done and compared to the ''bare'' cavities. In addition two single cell cavities have been fabricated, equipped with welded-on HOM couplers. They are being used to evaluate the HOM couplers with respect to multipacting, fundamental mode rejection and HOM damping as far as possible in a single cell. This paper describes the cavity design with respect to electromagnetic and mechanical features, the fabrication efforts and the results obtained with the different cavities existing at the time of this workshop.
Download or read book Proceedings written by and published by . This book was released on 1995 with total page 764 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New HOM Coupler Design for 3 9 GHz Superconducting Cavities at FNAL written by and published by . This book was released on 2007 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the 12th International Conference on High Energy Accelerators Held at Fermilab August 11 16 1983 written by Fermi National Accelerator Laboratory and published by . This book was released on 1983 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book First Cryogenic Tests with Jlab s New Upgrade Cavities written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Two types of 7-cell cavities have been developed for the upgrade of CEBAF to 12 GeV. The High Gradient type (HG) has been optimized with respect to the ratio of E{sub peak}/E{sub acc}. The Low Loss (LL) type has optimized shunt impedance and improved geometric factor. Each cavity type features four DESY-type coaxial Higher Order Mode (HOM) couplers and a waveguide input coupler. Design goals for these cavities have been set to E{sub acc} = 20 MV/m with an intrinsic Q{sub o} of 8 · 109 at 2.05 K.A niobium prototype of each cavity has been fabricated at JLab and both cavities have been evaluated at cryogenic temperatures after appropriate surface treatment. In addition, pressure sensitivity as well as Lorentz force detuning were evaluated. The damping of approximately 20 HOMs has been measured to verify the room temperature data. Several single cell cavities were tested in addition to multi cell cavities. We present in this contribution a summary of tests performed on the prototypes of the proposed cavities.
Download or read book EPAC96 written by S. Myers and published by . This book was released on 1996 with total page 980 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the 1993 Particle Accelerator Conference written by and published by . This book was released on 1993 with total page 1000 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book RF Superconductivity for Accelerators written by Hasan Padamsee and published by Wiley-VCH. This book was released on 2008-02-26 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces some of the key ideas of RF Superconductivity by using a pedagogic approach, and presents a comprehensive overview of the field. It is divided into four parts. The first part introduces the basic concepts of microwave cavities for particle acceleration. The second part is devoted to the observed behavior of superconducting cavities. In the third part, general issues connected with beam-cavity interaction and related issues for critical components are covered. The final part discusses applications of superconducting cavities to frontier accelerators of the future, drawing heavily on examples that are in their most advanced stage. Each part of the book ends in a problems section to illustrate and amplify text material as well as to draw on example applications of superconducting cavities to existing and future accelerators. FROM THE CONTENTS: * Basics * Performance of Superconducting Cavities * Couplers and Tuners * Frontier Accelerators
