| Paper | Title | Other Keywords | Page |
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| MOPA02 | 270 degree Electron Beam Bending System using Two Sector Magnets for Therapy Application | electron, target, linac, simulation | 50 |
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| The 270 degree doubly achromatic beam bending magnet system using two sector magnets has been designed mainly for treating cancer and skin diseases. The main requirements of the design of two magnet system is to focus an electron beam having a spot size less than 3 mm X 3 mm, energy spread within 3% and divergence angle <= 3 mrad at the target. To achieve these parameters the simulation was carried out using Lorentz-3EM software. The beam spot, divergence angle and energy spread were observed with respect to the variation in angles of sector magnets and drift distance. From the simulated results, it has been optimized that the first and second magnet has an angle 195 degree and 75 degree and the drift distance 64 mm. It is also observed that at the 1396, 2878 and 4677 A-turn, the optimized design produces 3324, 6221 and 9317 Gauss of magnetic field at median plane require to bend 6, 12 and 18 MeV electron respectively. The output parameters of the optimized design are energy spread 3 %, divergence angle ~ 2.8 mrad and spot size 2.6 mm. | |||
| MOPA15 | New Electronics Design for the European XFEL Re-entrant Cavity Monitor | electronics, cavity, FPGA, linac | 83 |
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| About one third of the beam position monitors (BPMs) in the European XFEL (E-XFEL) cryomodules will be re-entrant cavities. The BPM mechanics and Radio-Frequency front-end (RFFE) electronics are developed by CEA/Saclay. Two RFFEs and a digital back-end with two ADC mezzanines are integrated into a compact standalone unit called MBU (modular BPM unit) developed by PSI. The signal processing uses hybrids and a single stage downconversion to generate the signals sum and delta. Every RF/analog component of the re-entrant BPM electronics has been simulated with a Mathcad model and tested independently on test benches. The very low Q of the cavity monopole mode allows the new electronics to filter this mode at the dipole mode frequency and an IQ demodulation for delta and sum channels allow the digital back-end to determine the sign of the beam position just by comparing the phases of the channels, independently of beam arrival time jitter and external reference clock phase. This paper describes the design and architecture of a new re-entrant BPM electronics, including results of beam tests at FLASH that were performed to validate the chosen design. | |||
| MOPA18 | A Prototype Cavity Beam Position Monitor for the CLIC Main Beam | cavity, electronics, coupling, factory | 95 |
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| The Compact Linear Collider (CLIC) places unprecedented demands on its diagnostics systems. A large number of cavity beam position monitors (BPMs) throughout the main linac and beam delivery system must routinely perform with 50 nm spatial resolution. Multiple position measurements within a single 156~ns bunch train are also required. A prototype low-Q cavity beam position monitor has been designed and built to be tested on the CLIC Test Facility (CTF3) probe beam. This paper presents the latest measurements of the prototype cavity BPM and the design and simulation of the radio frequency (RF) signal processing electronics with regards to the final performance. Installation of the BPM in the CTF3 probe beamline is also discussed. | |||
| MOPA39 | Introduction of Photon BPMs in SOLEIL Global Orbit Feedback Systems | feedback, photon, operation, insertion | 150 |
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| SOLEIL global orbit feedback systems (slow and fast), based on 122 electron Beam Position Monitor (e-BPM) readings, are in operation since 2008 and give very satisfying performances (0.1Hz-500Hz vertical noise below 300 nm RMS and long term (8h) drifts below 1μm RMS). Whereas each straight section is equipped with an upstream and downstream e-BPM, there is no e-BPM next to a dipole magnet. For that reason, photon BPMs (x-BPMs) in the dipole beamline frontends give additional information that can be used to better stabilize the source point in the dipoles. In fact x-BPMs provide also a better position angular measurement resolution, as they are located at 4 meters from the source point. Results presented in this paper show that vertical position stability on bending magnet beamlines can be improved by including their x-BPM measurements in the global orbit feedback systems. As a first step x-BPMs have been introduced in the Slow Orbit FeedBack system (SOFB) that corrects the orbit with a repetition rate of 0.1Hz. In a second step x-BPMs will be introduced in the Fast Orbit FeedBack system (FOFB) running at a repetition rate of 10 kHz. | |||
| MOPB56 | Electron Cloud Measurements using a Time Resolved Retarding Field Analyzer at CesrTA | electron, detector, positron, storage-ring | 201 |
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Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, the US Department of Energy DE-FC02-08ER41538, DE-SC0006505 and US-Japan funding. The Cornell Electron Storage Ring has been reconfigured as a test accelerator (CesrTA) with positron or electron beam energies ranging from 2 GeV to 5 GeV. An area of research at CesrTA is the study of the growth, decay and mitigation of electron clouds in the storage ring. With a Retarding Field Analyzer (RFA), cloud electrons pass into the detector through an array of small holes in the wall of the beam-pipe. The electrons are captured by several collectors, so that the electron flux can be measured vs. horizontal position. Up to now, we have integrated the collector currents to provide DC measurements. We have recently constructed a new Time Resolved RFA, where the collector currents can be observed on the time scale of the bunch train in the storage ring. We present a summary of the design, construction and commissioning of this device, as well as initial beam measurements at CesrTA. |
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| TUPA16 | HOM Choice Study with Test Electronics for use as Beam Position Diagnostics in 3.9 GHz Accelerating Cavities in FLASH | cavity, HOM, electronics, electron | 364 |
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Funding: Work supported in part by the European Commission within the Framework Programme 7, Grant Agreement 227579 Higher Order Modes (HOM) excited by the beam in the 3.9 GHz accelerating cavities in FLASH can be used for beam position diagnostics, as in a cavity beam position monitor. Previous studies of the modal choices within the complicated spectrum have revealed several options*: cavity modes with high coupling to the beam, and therefore with the potential for better position resolution, but which are propagating within all 4 cavities, and modes localized in the cavities or the beam pipes, which can give localized position information, but which provide worse resolution. For a better characterization of these options, test electronics has been built, which can down convert various frequencies between about 4 and 9 GHz to 70 MHz. The performance of various 20 MHz bands has been estimated. The best resolution of 20 μm was found for some propagating modes. Based on this study one band at ca. 5 GHz was chosen for high resolution position monitoring and a band at ca. 9 GHz for localized monitoring. * N. Baboi et al., SRF2011, Chicago, IL, US |
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