Keyword: electron
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TUT2H6 Electron Sources and Polarization ion, gun, cathode, SRF 94
 
  • R. Xiang, J. Teichert
    HZDR, Dresden, Germany
  
  Funding: Supported by the European Community under the FP7 programme (EuCARD-2 and LA3NET) and by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1.
In this presentation the present electron sources and the relevant issues will be discussed. For the electron positron colliders and accelerator based light sources, the electron gun and injector design, are arguably the most critical part. There are a variety of electron source designs: DC guns, normal-conducting RF guns, superconducting RF gun and hybrid guns. All variants have their own ad-vantages and difficulties. We will overview the typical sources around the world, and compare their advantages and main challenges. The polarization production will also be discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT2H6  
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TUT3AH5 Electron Cloud and Ion Effects and Their Mitigation in FCC-ee ion, feedback, simulation, damping 120
 
  • K. Ohmi, H. Fukuma, M. Tobiyama
    KEK, Ibaraki, Japan
  
  Electron cloud and fast-ion instabilities are serious issues for colliders operated with high current and many bunches. We discuss the instabilities in FCC-ee/hh based on simulations and experiences of KEKB/SuperKEKB.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT3AH5  
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TUT3AH6 Electron Cloud at SuperKEKB ion, permanent-magnet, solenoid, operation 125
 
  • H. Fukuma, K. Ohmi, Y. Suetsugu, M. Tobiyama
    KEK, Ibaraki, Japan
  
  Several countermeasures such as ante-chambers, TiN coating, clearing electrodes, grooved structure and so on, have been taken to mitigate the electron cloud effects in the SuperKEKB positron ring. During phase 1 operation of SuperKEKB, which continued from this February to June, the electron cloud effects such as beam size blow-up, non-linear pressure increase, betatron tune shift along a bunch train and transverse coupled bunch instability were observed. Permanent magnets attached at bellows that generate longitudinal magnetic field in vacuum chambers were effective to reduce the electron cloud. This talk will cover following subjects about the electron cloud at SuperKEKB, 1) mitigation methods against the electron cloud, 2) observation of the electron cloud effects in phase 1 operation and 3) plan of further reduction of the electron cloud toward phase 2 operation which will start in the late FY2017.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT3AH6  
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TUT3AH7 Electron Cloud and Collective Effects in the Interaction Region of FCC-ee ion, impedance, simulation, quadrupole 130
 
  • E. Belli, G. Rumolo
    CERN, Geneva, Switzerland
  • E. Belli
    University of Rome "La Sapienza", Rome, Italy
  • E. Belli
    INFN-Roma, Roma, Italy
  • M. Migliorati
    University of Rome La Sapienza, Rome, Italy
  • M. Migliorati
    INFN-Roma1, Rome, Italy
  
  The FCC-ee is an e+e− circular collider designed to accommodate four different experiments in a beam energy range from 91 to 350 GeV and is a part of the Future Circular Collider (FCC) project at CERN. One of the most critical aspects of this new very challenging machine regards the collective effects which can produce instabilities, thus limiting the accelerator operation and reducing its performance. The following studies are focused on the Interaction Region of the machine. This talk will present preliminary simulation results of the power loss due to the wake fields generated by the electromagnetic interaction of the beam with the vacuum chamber. A preliminary estimation of the electron cloud build-up is also reported, whose effects have been recognized as one of the main limitations for the Large Hadron Collider at CERN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT3AH7  
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WET1H4 Measurement of Beam Polarization and Beam Energy in One Device ion, polarization, photon, laser 168
 
  • N.Yu. Muchnoi
    BINP SB RAS, Novosibirsk, Russia
  
  Funding: Russian Science Foundation N 14-50-00080
Electron beam interaction with the monochromatic laser radiation produces scattered photons and electrons due to the Compton effect. Both types of scattered particles carry the information about the polarisation (if any) and the energy of initial electrons in the beam. This report is focused on the properties of the scattered electrons. After a bending magnet these electrons leave the beam and their X-Y space distribution is supposed to be measured by the 2D pixel detector. We show that if the electron beam vertical emittance is sufficiently small, the shape of this distribution is an ellipse. Measurement of the length of the X-axis of this ellipse allow to calibrate accurately the bending field integral seen by the beam. The distribution of the electrons within the ellipse depends on the initial beam polarisation, allowing to measure its degree and direction. So we propose a universal Compton polarimeter with a unique feature of precise calibration of the LEP-style beam energy spectrometer. The approach is thought to be useful for the future high-energy e+/e− colliders, while the feasibility tests need to be performed on existing accelerators. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-WET1H4  
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WET3AH2 High Efficiency Klystron Development for Particle Accelerators ion, klystron, cavity, bunching 185
 
  • D.A. Constable
    Lancaster University, Lancaster, United Kingdom
  • A.Yu. Baikov
    MFUA, Moscow, Russia
  • G. Burt, V.C.R. Hill, C. Lingwood
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • I.A. Guzilov
    JSC Vacuum Devices Basic Technologies, Moscow, Russia
  • A. Jensen
    SLAC, Menlo Park, California, USA
  • R.D. Kowalczyk
    L-3, Williamsport, Pennsylvania, USA
  • R. Marchesin
    TED, Velizy, France
  • C. Marrelli
    ESS, Lund, Sweden
  • I. Syratchev
    CERN, Geneva, Switzerland
  
  Upcoming large scale particle accelerators, such as the Future Circular Collider (FCC), the Compact Linear Collider (CLIC) and the International Linear Collider (ILC) are expected to require RF drive on the order of 100 MW. Therefore, efforts to improve the efficiency of the specific RF source is of significant interest to the particle accelerator community. Klystrons are an attractive choice as the RF source, with the current state of the art tubes offering efficiencies up to 70%. The High Efficiency International Klystron Activity (HEIKA) collaboration seeks to improve upon this by considering novel methods of electron bunching. Such methods include the core oscillation method (COM), the bunching-alignment-collection (BAC) method, as well as the use of harmonic cavities. The theory behind these bunching methods will be discussed, along with their suitability for specific particle accelerators. In addition, results from numerical simulations predicting klystrons with efficiencies larger than 80% will be presented. Early experimental testing of tubes employing the BAC method will also be presented, demonstrating the efficiency improvements that the scheme offers.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-WET3AH2  
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WET3AH3 Extraction Line and Beam Dump for the Future Electron Positron Circular Collider ion, kicker, extraction, collider 188
 
  • A. Apyan
    ANSL, Yerevan, Armenia
  • K. Oide
    KEK, Ibaraki, Japan
  • F. Zimmermann
    CERN, Geneva, Switzerland
  
  The conceptual design of an extraction line and beam dump for the future electron positron circular collider is presented. The proposed extraction line, consisting of abort kicker system, spoilers and beam diagnostics apparatus transports the electron and positron beams to the main beam dumps. The beam must be spread over a large surface in order not to damage the beam dump and the window, which separates the ring from the dump. The extraction line redistributes bunches at different locations on the face of beam dump. Monte Carlo simulations using FLUKA have been performed to estimate the distribution of energy deposition on the window and beam dump to find the optimal absorber and its dimensions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-WET3AH3  
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WET3BH1 Improvement of Efficiency of Klystron to Apply the CPD Method ion, klystron, cavity, radiation 192
 
  • K. Watanabe
    KEK, Ibaraki, Japan
  
  A high power RF system for the particle accelerators needs large electrical power in the operation. An improvement of efficiency is also always required as a technology component for the energy saving. To improve efficiency of a high-power source, the CPD (Collector Potential Depression) method already was applied a Gyrotron to recovery the electrical energy form the collector loss. The CPD is an energy-saving scheme that recovers the kinetic energy of the spent electrons after generating rf power. A CPD klystron (E37703 CPD) was fabricated at 2013, to recycle an existing klystron of Toshiba E3786. The purpose of our study is to demonstrate the proof-of-principle of the CPD method to apply a klystron. A plane of R&D of CPD klystron at KEK will be reported in this meeting.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-WET3BH1  
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THS2H1 Summary of Impedance Issues and Beam Instabilities ion, impedance, feedback, wakefield 210
 
  • F. Zimmermann
    CERN, Geneva, Switzerland
  
  Funding: This work was supported in part by the European Commission under the FP7 Capacities project EuCARD-2, grant agreement 312453.
This paper summarizes the session on impedance issues and beam instabilities at the ICFA workshop on future circular electron-positron factories "eeFACT2016" held at the Cockcroft Institute, Daresbury, from 24 to 27 October 2016. This session also covered active beam stabilization by feedback systems. Beam-beam effects and coherent beam-beam instabilities were addressed separately and, therefore, are not included here. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-THS2H1  
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THS2H3 Summary of Beam Instrumentation and Beam Diagnostics Session ion, instrumentation, polarization, feedback 220
 
  • H. Fukuma
    KEK, Ibaraki, Japan
  
  This report is a summary of the beam instrumentation and beam diagnostics session of the eeFACT2016 workshop.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-THS2H3  
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