| Paper | Title | Page |
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| TUPS099 | A Study of the Surface Quality of High Purity Copper after Heat Treatment | 1771 |
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| The manufacturing flow of accelerating structures for the compact linear collider, based on diamond-machined high purity copper components, include several thermal cycles (diffusion bonding, brazing of cooling circuits, baking in vacuum, etc.). The high temperature cycles may be carried out following different schedules and environments (vacuum, reducing hydrogen atmosphere, argon, etc.) and develop peculiar surface topographies which have been the object of extended observations. This study presents and discusses the results of scanning electron microscopy (SEM) and optical microscopy investigations. | ||
| MOPC002 | Flow Induced Vibrations of the CLIC X-band Accelerating Structures | 65 |
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| Turbulent cooling water in the Compact Linear Collider (CLIC) accelerating structures will inevitably induce some vibrations. The maximum acceptable amplitude of vibrations is small, as vibrations in the accelerating structure could lead to beam jitter and alignment difficulties. A Finite Element Analysis model is needed to identify the conditions under which turbulent instabilities and significant vibrations are induced. Due to the orders of magnitude difference between the fluid motion and the structure's motion, small vibrations of the structure will not contribute to the turbulence of the cooling fluid. Therefore the resonant conditions of the cooling channels presented in this paper, directly identify the natural frequencies of the accelerating structures to be avoided under normal operating conditions. In this paper a 2D model of the cooling channel is presented finding spots of turbulence being formed from a shear layer instability. This effect is observed through direct visualisation and wavelet analysis. | ||
| MOPC037 | Engineering Design and Fabrication of X-band Damped Detuned Structure for the CLIC Study | 154 |
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A Damped Detuned Structure (DDS), known as CLICDDSA*, has been designed for the Compact Linear Collider (CLIC) study, and is presently under fabrication. The wakefield in DDS structures is damped using a combination of detuning the frequencies of beam-excited higher order modes and by light damping, through slot-coupled manifolds. The broad principles of the design are similar to that used in the NLC/GLC**. This serves as an alternative to the present baseline CLIC design which relies on heavy damping. CLICDDSA is conceived to be tested for its capacity to sustain high gradients at CERN. This structure operates with a 120 degrees phase advance per cell. We report on engineering design and fabrication details of the structure consisting of 24 regular cells plus 2 matching cells at both ends, all diffusion bonded together. This design takes into account practical mechanical engineering issues and is the result of several optimizations since the earlier CLICDDS designs.
* V. F. Khan et al., “Recent Progress on a Manifold Damped and Detuned Structure for CLIC”, Proc. of IPAC10, WEPE032, p. 3425 (2010). ** R.M. Jones et al., Phys. Rev. STAB 9, 102001 (2006). |
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| MOPC038 | Engineering Design and Fabrication of Tapered Damped X-band Accelerating Structures | 157 |
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| The accelerating structures (AS) are one of the main components of the Compact LInear Collider (CLIC), under study at CERN. Each AS contains about 30 copper disks, which form the accelerating cavity. A fully featured AS is very challenging and requires several technologies. Different damping methods, waveguides, vacuum manifolds, slots and choke, result in various design configurations. In the CLIC multibunch AS, called TDS (Tapered Damped Structure), each cell is damped by its four waveguides, which are extended by channels machined in dedicated external vacuum manifolds. The manifolds combine few functions such as damping, vacuum pumping and cooling. Silicon carbide absorbers, fixed inside of each manifold, are required for effective damping of High Order Modes. CERN is producing X-band RF structures in close collaboration with a large number of laboratories taking advantage of their large expertise and test facilities. The fabrication includes several steps from the machining to the final assembly, including quality controls. This paper describes the engineering design and fabrication procedure of the X-band AS with damping material, by focusing on few technical solutions. | ||
| TUPC008 | CLIC Two-Beam Module for the CLIC Conceptual Design and Related Experimental Program | 1003 |
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| The Compact LInear Collider (CLIC), being studied at CERN, involves the design and integration of many different technical systems, tightly bound and influencing each other. For the construction of two main linacs it has been decided to proceed with a modular design, and repetitive two-beam modules of a few types were defined. The modules consist of micro-precision components operating under ultra-high vacuum as required by the beam physics. For the CLIC Conceptual Design Report, the development and system integration is mainly focused on the most complex module type containing the highest number of components and technical systems. For proving the proper functioning of the needed technical systems and confirming their feasibility it has been decided to build four prototype modules and test them without beam. In addition, three modules have to be produced in parallel for tests in the CLIC Experimental Area with beam. This paper is focused on the design of the different technical systems and integration issues of the two-beam module. The experimental program for the prototype modules is also recalled. | ||
| TUPC012 | Fabrication and Validation of the Prototype Supporting System for the CLIC Two-beam Modules | 1015 |
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| The Compact LInear Collider (CLIC), currently under study at CERN, aims at the development of a Multi-TeV e+ e- collider and relies upon a novel two-beam acceleration concept. In the two-beam acceleration, the Radio Frequency (RF) power is extracted from a low energy but high-intensity particle beam, and it is transferred to a parallel high energy main beam. The two-beam modules are the smallest repetitive units which compose the two linacs. The RF structures are the most precise components and they are mounted and aligned on specially developed supporting system, which provides stability and quick re-positioning. The supporting girders have stringent stiffness and damping requirements, imposed by beam physics requirements. In addition, several constraints, such as allocated space and weight limitation have to be taken into consideration. This paper describes different girder configurations following various fabrication techniques and materials. Extensive qualification measurements have been performed on the first prototype units, and the main results are also presented. | ||
| TUPS098 | Machining and Characterizing X-band RF-structures for CLIC | 1768 |
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| The Compact Linear Collider (CLIC) is currently under study at CERN as a potential multi-TeV e+e collider. The manufacturing and assembling tolerances for making the required RF components are essential for CLIC to perform efficiently. Machining techniques are relevant to the construction of ultra-high-precision parts for the Accelerating Structures (AS). Optical-quality turning and ultra-precision milling using diamond tools are the main manufacturing techniques identified to produce ultra-high shape accuracy parts. A shape error of less than 5 micrometres and roughness of Ra 0.025 are achieved. Scanning Electron Microscopy (SEM) observation as well as sub-micron precision Coordinate Measuring Machines (CMM), roughness measurements and their crucial environment were implemented at CERN for quality assurance and further development. This paper focuses on the enhancements of precision machining and characterizing the fabrication of AS parts. | ||