Download or read book Fundamental and HOM Coupler Design for the Superconducting Parallel Bar Cavity written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The superconducting parallel-bar cavity is currently being considered as a deflecting system for the Jefferson Lab 12 GeV upgrade and as a crabbing cavity for a possible LHC luminosity upgrade. Currently the designs are optimized to achieve lower surface fields within the dimensional constraints for the above applications. A detailed analysis of the fundamental input power coupler design for the parallel-bar cavity is performed considering beam loading and the effects of microphonics. For higher beam loading the damping of the HOMs is vital to reduce beam instabilities generated due to the wake fields. An analysis of threshold impedances for each application and impedances of the modes that requires damping are presented in this paper with the design of HOM couplers.

Download or read book Analysis of HOM Properties of Superconducting Parallel Bar Deflecting Crabbing Cavities written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The superconducting parallel-bar cavity is currently being considered for a number of deflecting and crabbing applications due to improved properties and compact design geometries. The 499 MHz deflecting cavity proposed for the Jefferson Lab 12 GeV upgrade and the 400 MHz crab cavity for the proposed LHC luminosity upgrade are two of the major applications. For high current applications the higher order modes must be damped to acceptable levels to eliminate any beam instabilities. The frequencies and R/Q of the HOMs and mode separation are evaluated and compared for different parallel-bar cavity designs.

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 Design and Development of Superconducting Parallel Bar Deflecting Crabbing Cavities written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties that is being considered for a number of applications. We present the designs of a 499 MHz deflecting cavity developed for the Jefferson Lab 12 GeV Upgrade and a 400 MHz crabbing cavity for the LHC High Luminosity Upgrade. Prototypes of these two cavities are now under development and fabrication.

Download or read book Mechanical Study of Superconducting Parallel Bar Deflecting Crabbing Cavities written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The superconducting parallel-bar deflecting/crabbing cavities have improved properties compared to conventional cavity structures. It is currently being considered for number of applications. The mechanical design analysis is performed on two designs of the 499 MHz parallel-bar deflecting cavity for the Jefferson Lab 12 GeV upgrade. The main purpose of the mechanical study is to examine the structural stability of the cavities under the operating conditions in the accelerators. The study results will suggest the need for additional structural strengthening. Also the study results will help to develop a concept of the tuning method. If the cavity is to be installed in the accelerator it should satisfy a certain design parameters due to the safety requirements (for example, pressure system requirements) which are much severe condition than the actual operating condition.

Download or read book Design Optimization of Superconducting Parallel bar 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 parallel-bar structure is a new superconducting geometry [1] whose features and properties may have significant advantages over conventional superconducting deflecting and crabbing cavities for a number of applications. Jefferson Lab is in need for a 499 MHz, 11 GeV rf separator as part of its 12 GeV upgrade program. We report on design optimization studies performed to-date for this and other applications.

Download or read book Designs of Superconducting Parallel Bar Deflecting Cavities for Deflecting Crabbing Applications written by and published by . This book was released on 2011 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is currently being considered for a number of applications. The new parallel-bar design with curved loading elements and circular or elliptical outer conductors have improved properties compared to the designs with rectangular outer conductors. We present the designs proposed as deflecting cavities for the Jefferson Lab 12 GeV upgrade and for Project-X and as crabbing cavities for the proposed LHC luminosity upgrade and electron-ion collider at Jefferson Lab.

Download or read book Fundamental Power Couplers for Superconducting Cavities written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamental power couplers (FPC's) for superconducting cavities must meet very strict requirements to perform at high power levels (hundreds of kilowatts) and in a variety of conditions (CS, pulsed, travelling wave, standing wave) without adversely affecting the performance of the cavities they are powering. Producing good coupler designs and achieving operational performances in accelerator environments are challenging tasks that have traditionally involved large resources from many laboratories. The designs involve state-of-the-art activities in RF, cryogenic and mechanical engineering, materials science, vacuum technology, and electromagnetic field modeling. Handling, assembly and conditioning procedures have been developed to achieve ever-increasing power levels and more reliable operation. In this paper, the technical issues associated with the design, construction, assembly, processing, and operation of FPC's will be reviewed, together with the progress in FPC activities in several laboratories during the past few years.

Download or read book Multipacting Analysis of the Superconducting Parallel bar Cavity written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is being considered for a number of applications. Multipacting can be a limiting factor to the performance of in any superconducting structure. In the parallel-bar cavity the main contribution to the deflection is due to the transverse deflecting voltage, between the parallel bars, making the design potentially prone to multipacting. This paper presents the results of analytical calculations and numerical simulations of multipacting in the parallel-bar cavity with resonant voltage, impact energies and corresponding particle trajectories.

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 State of the Art Couplers for Superconducting RF Cavities written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamental power couplers for RF particle accelerators are the most important components that interface with the accelerating structures. In the case of superconducting cavities, the main function of providing the appropriate amount of power to the cavity's fields and to the beams is dwarfed by the requirements that the couplers must meet in order to harmoniously blend into the vacuum, cryogenic, and electromagnetic environment. Recently, a lot of progress has been made in the areas critical to the successful design, construction, and operation of fundamental power couplers. Simulations are now routinely performed that allow the prediction of electromagnetic, multipacting, thermal, and mechanical properties of couplers. From these studies, better designs have been conceived which can minimize potential problems ahead of construction. Judicious use of materials and the implementation of clean practices and of careful conditioning have gradually increased the power levels at which couplers can safely operate. Machine operation at hundreds of kilowatts has been achieved in CW at KEK and Cornell, and in a pulsed mode at the TESLA Test Facility (TTF). Test stand operations in CW at the megawatt level (Accelerator for the Production of Tritium) and in pulse mode at a peak power of 2 MW (Spallation Neutron Source, TTF version II) have been achieved. The recent progress indicates that the understanding of the behavior of fundamental power couplers is rapidly increasing and that optimal designs are being developed which will allow in the future to attain routinely megawatt power levels necessary for high beam power machines under construction and under study.

Download or read book Fundamental Power Coupler Development for Low beta Superconducting Cavities written by Jon Joseph Wlodarczak and published by . This book was released on 2008 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Coaxial Coupling Scheme for Fundamental and Higher Order Modes in Superconducting Cavities written by and published by . This book was released on 2008 with total page 65501 pages. Available in PDF, EPUB and Kindle. Book excerpt: Higher Order Modes generated by a particle beam passing through a superconducting accelerating cavity have to be damped to avoid beam instabilities. A coaxial coupler located in the beam pipes of the cavities provides for better propagation of HOMs and strong damping in appropriate HOM dampers. The whole damping device can be designed as a detachable system. If appropriately dimensioned, the RF currents can be minimized at the flange position. Additionally, the coaxial system also provides efficient coupling of fundamental mode RF power into the superconducting cavity. Compared to presently available solutions for HOM damping, this scheme provides for several advantages: stronger HOM damping, attachable solution, and exchangeability of the HOM damping device on a cavity, less complexity of the superconducting cavity, possible cost advantages. This contribution discusses modeling, which lead to an optimized layout of a cavity-coupler system and describes results from the room temperat.

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 Cavity and HOM Coupler Design for CEPC Supported by National Natural Science Foundation of China 11175192 written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In this paper we will show a cavity and higher order mode (HOM) coupler designing scheme for the Circular Electron-Positron Collider (CEPC) main ring. The cavity radio frequency (RF) design parameters are shown in this paper. The HOM power is calculated based on the beam parameters in the Preliminary Conceptual Design Report (Pre-CDR). The damping results of the higher order modes (HOMs) and same order modes (SOMs) show that they reach the damping requirements for beam stability.

Download or read book The Prototype Fundamental Power Coupler For The Spallation Neutron Source Superconducting Cavities written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Each of the 805 MHz superconducting cavities of the Spallation Neutron Source (SNS) is powered via a coaxial Fundamental Power Coupler (FPC) with a 50 Omega impedance and a warm planar alumina window. The design is derived from the experience of other laboratories; in particular, a number of details are based on the coupler developed for the KEK B-Factory superconducting cavities. However, other design features have been modified to account for the fact that the SNS FPC will transfer a considerably lower average power than the KEK-B coupler. Four prototypes have been manufactured so far, and preliminary tests performed on two of them at Los Alamos National Laboratory (LANL). During these tests, peak powers of over 500 kW were transferred through the couplers in the test stand designed and built for this purpose. This paper gives details of the coupler design and of the results obtained from the RF tests on the test stand during the last few months. A more comprehensive set of tests is planned for the near future.

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.