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| MOPP012 | DC Breakdown Experiments for CLIC | collider, linear-collider, cathode, vacuum | 577 | |||||
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For the production of the Compact Linear Collider (CLIC) RF structures, a material capable of sustaining high electric field, with a low breakdown rate and showing low damages after breakdowns is needed. A DC breakdown study is underway at CERN in order to test candidate materials and surface preparations, and also to have a better understanding of the breakdown mechanism. The saturated breakdown fields of several metals and alloys have been measured, ranging from 100MV/m for Al to 900MV/m for stainless steel, being around 150MV/m for Cu, CuZr and Glidcop, 300MV/m for W, 400MV/m for Mo, Nb and Cr, 650MV/m for V, and 750MV/m for Ti for example. Titanium shows a strong material displacement after breakdowns, while Cu, Mo and stainless steel are more stable. The conditioning speed of Mo can be significantly improved by removing oxides at the surface with a heat treatment, typically at 875°C for 2 hours. DC breakdown rate measurements have been done with Cu and Mo electrodes, showing similar results as in RF experiments: the breakdown probability seems to exponentially increase with the applied field.
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| MOPP045 | Study of the Validity of K. Bane's Formulae for the CLIC Accelerating Structure | dipole, impedance, target, luminosity | 646 | |||||
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The comprehension of short range wake is essential for the design of CLIC. Useful tools are the Karl Bane's formulae which predict the short range wake for periodic 2D symmetry structures. The comparison of 2D computations based on ABCI with predicted results and the study of the range of validity of these formulae are the subjects of this paper. A new fitting of the computational results is proposed for structures with very small aperture. A model for rounded iris structures is also proposed.
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| MOPP137 | MultiPac 2.1 - Multipacting Simulation Package with a 2D FEM Field Solver for a Microsoft Windows System | electron, simulation, superconductivity, vacuum | 880 | |||||
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MultiPac 2.1 is a multipacting simulation package for analyzing electron multipacting in axisymmetric RF structures with TM0nl mode, such as RF cavities, coaxial input couplers and ceramic windows. The original package was written by P. Ylä-Oijala*, and works with MATLAB 5.0 or 6.0 on Linux operating system. In order to use this code easily for Microsoft Windows customers, we have transferred the MultiPac 2.1 from the Linux system to the Microsoft Windows system. The revised MultiPac can work with Microsoft Windows MatLab 6.0 or later editions smoothly. In this paper, the installation and operation of the Windows MutiPac 2.1 have been introduced.
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*This work was supported by the 21C Frontier R&D program in Ministry of Science and Technology of the Korean Government. |
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| TUPC023 | Design of the Transverse C-band Deflecting Structure for Measurement of Bunch Length in X-FEL | resonance, coupling, simulation, klystron | 1098 | |||||
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In SPring-8, the 8 GeV X-FEL with a short length of about 700 m is under construction. An electron beam with a bunch length in duration of less than 200 fs is indispensable for stable and brilliant X-ray radiation. We planned to measure the short bunch length with a transverse RF deflector. A bunch measuring system including the deflector must be located within 15 m of a bunch compressor at a beam energy of 1.45 GeV. To install the system in the restricted space, we need a deflector generating a transverse deflecting voltage over 40 MV. Therefore a new C-band deflecting structure was designed. It is a periodic disk-loaded structure with a racetrack-shaped iris in the center of each disk. The deflecting resonant mode is the HEM11-5π/6 mode of a backward traveling-wave and its transverse shunt impedance is more than 12 MΩ/m. The racetrack-shaped iris serves both as a cell-to-cell coupler and a beam passing hole, prevents rotation of the deflection plane of the HEM11 mode and makes the deflecting mode resonant stably. We represent the details and merits of the C-band structure with the demanded performance in this paper.
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| TUPC080 | Fermi Low-energy Transverse RF Deflector Cavity | emittance, electron, linac, coupling | 1239 | |||||
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The layout of FERMI@Elettra will include a transverse S-band RF deflector that will be located after the first bunch compressor (BC1) at 250 MeV. The deflector will operate in a vertical deflecting mode and coupled to a downstream dipole will be used to measure the electron bunch length and in particular to allow time-resolved beam quality measurements such as horizontal slice emittance and slice energy spread. In this paper we discuss the electron bunch deflection at 250 MeV taking into account the principal elements that dominate the selection of the transverse peak voltage specification: the finite transverse emittance, the resolution of OTR screens and the desired number of the slice divisions along the bunch that we wish to observe. The RF deflector proposed here is a frequency scaled version of the 5-cell standing wave SPARC structure.
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| WEIM04 | Highly Customized Industrialized Linacs for Applications in Scientific Research | linac, electron, proton, vacuum | 1967 | |||||
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Industrial capabilities and experience in linac design and manufacturing shall be given for the various types of scientific applications. Furthermore the process from linac contracting through establishing a project team and adequate human and machine ressources for fulfilling the technical, schedule and pricing requirements shall be described.
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