Download or read book Design of HOM Coupler Prototype for the APT Superconducting RF Cavities written by and published by . This book was released on 2001 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Beam dynamics calculations for the Accelerator Production of Tritium (APT) proton linac suggest that wakefields, which are excited during beam operation, would not lead to beam-breakup instabilities. However, in the superconducting (SC) radio-frequency (RF) cavities of the APT linac, higher-order modes (HOMs), whose frequencies are below the beam tube cut-off fiequency, can be sufficiently excited by the beam to add significantly to the heat load removed by the helium refrigerator. In this paper, we present a design of an HOM coupler for the APT RF cavities that will remove this power to a resistive load at room temperature.

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 RF Power and HOM Coupler Tutorial written by B. Rusnak and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Radio frequency (RF) couplers are used on superconducting cavities to deliver RF power for creating accelerating fields and to remove unwanted higher-order mode power for reducing emittance growth and cryogenic load. RF couplers in superconducting applications present a number of interdisciplinary design challenges that need to be addressed, since poor performance in these devices can profoundly impact accelerator operations and the overall success of a major facility. This paper will focus on critical design issues for fundamental and higher order mode (HOM) power couplers, highlight a sampling of reliability-related problems observed in couplers, and discuss some design strategies for improving performance.

Download or read book Results of the APT RF Power Coupler Development for Superconducting Linacs written by and published by . This book was released on 2001 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: For the new baseline APT (Accelerator Production of Tritium) linac design, the power couplers are required to transmit 420 kW of CW RF power to the superconducting cavities at 700 MHz. These couplers consist of an airside waveguide-to-coax transition, an air/vacuum break made by two planar, coaxial windows, and a vacuum-side coaxial antenna section. The coaxial antenna allows adjustability of the RF matching to the superconducting cavities. Design, fabrication, and testing of the power coupler/window occurred over the last four years, and room temperature testing of the prototype design is complete. Coupler/window assemblies have transmitted power to 1 MW, CW and have handled full reflected 850 kW, CW over a limited standing-wave phase range. Couplers were tested with a portion of the outer conductor cooled by liquid nitrogen to study the effects of condensed gases. No hard multipacting barriers were encountered during any of this room temperature testing. Final results, conclusions, and lessons learned about the coupler design, fabrication, and testing will be discussed.

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 La publication des emprises du tournoy qui doibt estre faict Paris ville capitale du royaume de France written by Benoît Rigaud and published by . This book was released on 1559 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thermal Study of HOM Couplers for Superconducting RF Cavities written by and published by . This book was released on 1993 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Comparative Simulation Studies of Multipacting in Higher Order Mode Couplers of Superconducting RF Cavities written by and published by . This book was released on 2014 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multipacting (MP) in higher-order-mode (HOM) couplers of the International Linear Collider (ILC) baseline cavity and the Continuous Electron Beam Accelerator Facility (CEBAF) 12 GeV upgrade cavity is studied by using the ACE3P suites, developed by the Advanced Computations Department at SLAC. For the ILC cavity HOM coupler, the simulation results show that resonant trajectories exist in three zones, corresponding to an accelerating gradient range of 0.6-1.6 MV/m, 21-34 MV/m, 32-35 MV/m, and> 40MV/m, respectively. For the CEBAF 12 GeV upgrade cavity HOM coupler, resonant trajectories exist in one zone, corresponding to an accelerating gradient range of 6-13 MV/m. Potential implications of these MP barriers are discussed in the context of future high energy pulsed as well as medium energy continuous wave (CW) accelerators based on superconducting radio frequency cavities. Frequency scaling of MP's predicted in HOM couplers of the ILC, CBEAF upgrade, SNS and FLASH third harmonic cavity is given and found to be in good agreement with the analytical result based on the parallel plate model.

Download or read book Design Fabrication and Testing of Superconducting RF Cavities for High Average Beam Currents written by David Joseph Meidlinger and published by . This book was released on 2007 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A HIGH POWER RF COUPLER DESIGN FOR MUON COOLING RF CAVITIES written by and published by . This book was released on 1999 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a high power RF coupler design for an interleaved [pi]/2 805 MHz standing wave accelerating structure proposed for an muon cooling experiment at FNAL. The coupler, in its simplest form, is a rectangular waveguide directly connected to an accelerating Cell through an open slot on the cavity side-wall or end-plates. Two of such couplers are needed to feed the interleaved cavities. Current high power RF test requires the coupler to be at critical coupling. Numerical simulations on the coupler designs using MAFIA will be presented.

Download or read book RF Design and Processing of a Power Coupler for Third Harmonic Superconducting Cavities written by and published by . This book was released on 2007 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: The FLASH user facility providing free electron laser radiation is built based on the TTF project at DESY. Fermilab has the responsibility for the design and processing of a third harmonic, 3.9 GHz, superconducting cavity which is powered via a coaxial power coupler. Six power couplers have been manufactured at CPI after successful design of the power coupler including RF simulation, multipacting calculation, and thermal analysis. The power couplers are being tested and processed with high pulsed power in an elaborate test stand at Fermilab now. This paper presents the RF design and processing work of the power coupler.

Download or read book RF THERMAL COMBINED SIMULATIONS OF A SUPERCONDUCTING HOM COAXIAL COUPLER written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To benchmark a multi-physics code VORPAL developed by Tech-X, the High Order Mode (HOM) coaxial coupler design implemented in Jefferson Lab?s 12GeV upgrade cryomodules is analyzed by use of commercial codes, such as ANSYS, HFSS and Microwave Studio. Testing data from a Horizontal Test Bench (HTB) experiment on a dual-cavity prototype are also utilized in the verification of simulation results. The work includes two stages: first, the HOM feedthrough that has a high RRR niobium probe and sapphire insulator is analyzed for the RF-thermal response when there is travelling wave passing through; second, the HTB testing condition is simulated and results from simulation are compared to thermal measurements from HTB tests. The analyses are of coupled-field nature and involve highly nonlinear temperature dependent thermal conductivities and electric resistivities for the eight types of materials used in the design. Accuracy and efficiency are the main factors in evaluation of the performance of the codes.

Download or read book External Q Studies for APT Superconducting Cavity Couplers written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Coupling coefficients for the APT superconducting cavity couplers have been predicted using an improvement of the method previously developed for the French Trispal project. The authors here present the method and a proof of the formula used to compute the external Q. Measurements on a single-cell copper cold model exhibited a very good agreement against simulation. Then, they established that the original coupler design lead to an insufficient coupling in [beta] = 0.64 cavities. Different solutions were proposed to fix this problem, like combining impedance discontinuities in the line and an off-centered disc end tip. Finally, it was decided to increase the beam tube diameter though it has some influence on the cavity end-cell performance.

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 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 DIAGNOSIS ANALYSIS AND RESOLUTION OF THERMAL STABILITY ISSUES WITH HOM COUPLERS ON PROTOTYPE CEBAF SRF CAVITIES written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: During initial testing of the prototype cavities incorporated into the developmental cryomodule Renascence severe thermal stability issues were encountered during CW operation. Additional diagnostic instrumentation was added. This enabled identification of an unanticipated thermal impedance between the HOM coupler probe feedthrough assembly and the cavity beamtube. Subsequent detailed FE analysis successfully modeled the situation and indicated the need for alternate cooling path for the couplers on those cavities. HOM damping was measured to be adequate employing only two of the four HOM couplers. The two pickup probes on the couplers at the input power coupler side of each cavity were removed, the remaining HOM probe feedthroughs were heat stationed to two-phase helium supply piping, and a novel heat sink was added to station both the inner and outer conductors of the remaining HOM rf cables. The characterization measurements, analysis, modifications, and resulting performance are presented.