IPAC2014 - Classification: 07 Accelerator Technology Main Systems / T14 Vacuum Technology

Paper	Title	Page
WEPME018	CERN Vacuum System Activities during the Long Shutdown 1: The LHC’s injector chain.	2291
	J.A. Ferreira Somoza, P. Chiggiato CERN, Geneva, Switzerland
	During the long shutdown 1 (LS1), several maintenance, consolidation and upgrade activities have been carried out in LHC’s injector chain. Each machine has specific vacuum requirements and different history, which determine the present status of the vacuum components, their maintenance and consolidation needs. The present work presents the priorities agreed at the beginning of the LS1 period and their implementation. Of particular relevance are the interventions in radioactive controlled areas where several leaks due to stress corrosions stopped the operations in the past years. The strategy to reduce the collective dose is presented, in particular the use of remote controlled robots. An important part of the work performed during this period involves supporting other teams (acceptance tests, new equipment installation, etc.). Finally, as a result of the LS1 experience, a medium to long term strategy is depicted, focusing on the preparation of the next shutdown (LS2) and the integration of LINAC4 in the injector chain during the same period.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME018
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WEPME025	Design and Performance of Ultimate Vacuum System for the AREAL Test Facility	2311
	A.A. Gevorgyan, V.S. Avagyan, B. Grigoryan, T.H. Mkrtchyan, A.S. Simonyan, V. V. Vardanyan CANDLE SRI, Yerevan, Armenia
	The design specification of the AREAL test facility require the residual pressure at the level of 1nTorr with beam through entire vacuum chamber. We present the main features of the vacuum system, including the design and fabrication peculiarities of the dedicated components like dipole magnet stainless steel vacuum chamber and the cubes for beam diagnostic stations. The philosophy and instrumentation of the vacuum system are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME025
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WEPME026	Layout of the Vacuum System for a New ESRF Storage Ring	2314
	M. Hahn, J.C. Biasci, H.P. Marques ESRF, Grenoble, France
	The proposed 7-bend achromat lattice for the new 6 GeV electron storage ring of the European Synchrotron Radiation Facility imposes a change of the entire vacuum system. Small bore magnets will require low conductance vacuum chambers. Conventional vacuum pumps will have to be assisted by distributed pumping provided by Non-Evaporable Getter (NEG) coating. The time constraints for design, prototyping, pre-assembly, installation and commissioning of the new systems require simple solutions and the use of existing expertise where possible. In this paper the draft layout of the vacuum system will be explained, information about the expected dynamic pressure distribution and conditioning will be given. Some technical solutions to resolve specific issues arising from the small vacuum chamber dimensions and the dense arrangement of components are described.
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WEPME028	Systematic Measurement of the Pumping Capabilities of Cryogenic Surfaces	2317
SUSPSNE102	use link to see paper's listing under its alternate paper code
	F. Chill, O.K. Kester IAP, Frankfurt am Main, Germany L.H.J. Bozyk, O.K. Kester, P.J. Spiller GSI, Darmstadt, Germany
	The quality of the beam vacuum is crucial for the stable operation of synchrotrons with high intensity heavy ions. Cryogenic surfaces are capable of pumping residual gases by cryocondensation until the saturated vapor pressure (SVP) is reached. Even at LHe temperatures the SVP of hydrogen is too high. If the surface coverage is sufficiently low, residual gas can also be bound by cryosorption, yielding in acceptable low pressures. These pumping capabilities can be described by two parameters, both dependent on surface temperature and coverage: The sticking probability (SP), that is the chance of an impinging gas particle to be bound, and the mean sojourn time (MST) of a particle on the surface. To acquire these parameters, an experimental setup is currently built at GSI. It consists of a cryogenic chamber, cooled by a cold head and a warm part with vacuum diagnostics and gas inlet. It allows monitoring the pumping speed and also the equilibrium pressure of the cryogenic part from which the SP and the MST can be deducted. The results will be used to further improve the accuracy of the dynamic vacuum simulations in cryogenic areas of particle accelerators.
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WEPME029	Development of a Field Emitter-based Extractor Gauge for the Operation in Cryogenic Vacuum Environments	2320
	M. Lotz, O.K. Kester, St. Wilfert GSI, Darmstadt, Germany
	This paper presents an investigation of a CNT emitter-based extractor gauge which is designed for pressure reading in cryogenic ultra-high vacuum systems. The results show that the modified gauge works well in both room temperature and cryogenic vacuum environments. Furthermore, it could be demonstrated that the modified gauge responds much more sensitive to small pressure fluctuations in cryogenic environments than the same gauge type having a hot-filament cathode.
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WEPME030	Design and Construction of a Prototype Sputter ion Pump in ILSF	2323
	O. Seify, H. Ghasem, S. Kashani, J. Rahighi ILSF, Tehran, Iran H. Ghasem IPM, Tehran, Iran
	Design and construction process of special kind of sputter ion pump is described briefly in this paper. In order to investigate the optimization of effective parameters in choosing and designing ILSF ion pumps, this pump has been designed and manufactured. By optimizing some parameters such as dimension and shape of penning cells, anode voltage, magnetic field and internal structure of pump, it is possible to significantly decrease the cost of construction and operation of synchrotron vacuum system. One of the most important advantages of this design, is that the initial parameters and finally internal structure of the prototype pump are changeable easily. The effect of parameters like anode voltage, magnetic field etc. on pumping speed and final pressure are described. With the existing optimization it is expected that an ultimate pressure of 1x10^-11 Torr could be achieved.
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WEPME032	Detailed Investigation of the Low Energy Secondary Electron Yield of Technical Cu and its Relevance for LHC	2329
	R. Cimino, L.A. Gonzalez, A.L. Romano INFN/LNF, Frascati (Roma), Italy R. Cimino, G. Iadarola, G. Rumolo CERN, Geneva, Switzerland R. Larciprete ISM-CNR, Rome, Italy
	The detailed study of the Secondary Electron Yield (SEY) of technical Cu for very low electron landing energies (from 0 to 30 eV) is very important for electron cloud build up in high intensity accelerators and in many other fields of research. However, this question has been rarely addressed due to the intrinsic experimental complexity to control very low energy electrons. Furthermore, several results published in the past have been recently questioned for allegedly suffering from experimental systematics. In this paper, we critically review the experimental method used to study low energy SEY and define more precise energy regions, in which the experimental data can be considered valid. The new SEY curves are then fed into e-cloud simulation codes to address their impact for electron cloud predictions in the LHC.
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WEPME033	Search for New e-cloud Mitigator Materials for High Intensity Particle Accelerators	2332
	R. Cimino, S.T. O'connor, A.L. Romano INFN/LNF, Frascati (Roma), Italy V. Baglin, G. Bregliozzi, R. Cimino CERN, Geneva, Switzerland M.R. Masullo INFN-Napoli, Napoli, Italy S. Petracca, A. Stabile INFN-Salerno, Baronissi, Salerno, Italy
	Electron cloud is an ubiquitous effect in positively charged particle accelerators and has been observed to induce unwanted detrimental impacts on beam quality, stability, vacuum etc. A great effort has been recently devoted to the search of new material morphology and/or coatings which can intrinsically mitigate beam instabilities deriving from electron cloud effects. In this context, we present some characterization of Cu foams, available from the market, and their qualification in terms of their vacuum behavior, impedance, secondary electron yield, gas desorption etc. More experimental effort is required to finally qualify foams as a mature technology to be integrated in accelerator environments. But, our preliminary results suggests that, when compatible with geometrical constrains, Cu foams can be utilized when low desorption yields are required and as e-cloud moderator in future particles accelerators.
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WEPME034	Soft X-ray Reflectivity and Photoelectron Yield of Technical Materials: Experimental Input for Instability Simulations in High Intensity Accelerators	2335
	R. Cimino INFN/LNF, Frascati (Roma), Italy R. Cimino CERN, Geneva, Switzerland F. Schäfers HZB, Berlin, Germany
	High luminosity particle accelerators can suffer from serious performance drop or limitations due to interaction of the synchrotron radiation produced by the accelerator itself with the accelerator walls. Such interaction may produce a number of photoelectrons, that can either seed electron cloud related instabilities and/or interact anyway with the beam itself, potentially causing its deterioration. To correctly take these effects into account simulation codes depends on the realistic knowledge of Reflectivity and Photoelectron Yield of technical material. In this work we present relevant experimental data for some of the mostly used technical surfaces in accelerators.
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WEPME035	Beam Loss Suppression by Improvement of Vacuum System in J-PARC RCS	2338
	J. Kamiya, M. Kinsho, S. Noshiroya, K. Yamamoto JAEA/J-PARC, Tokai-mura, Japan
	In high power beam accelerators, pressure of the beam line directly affects the amount of the beam loss. For example, in the early 1970’s in CERN’s Intersecting Storage Ring (ISR), the ion-induced pressure bump produced the fall-off of the beam current. 3GeV synchrotron (RCS) in J-PARC is no exception. RCS is one of the most high power beam accelerators in the world. It aims the 1 MW beam power, which corresponds to the average and peak beam current of 333 uA and about 10 A, respectively. In the present stage, the injection line called L3BT line (Linac to 3GeV Beam Transport line), is the section, where the pressure notably produces the beam loss. In this line, H⁻ beam from Linac was converted to H⁰ by charge stripping due to the interaction between H⁻ beam and the residual gas molecules. Such H⁰ was not bended by the injection septum magnets and directly hit the vacuum wall. We decided to add the vacuum pumps in this line to reduce the residual gas molecules. We will present the effectivity of the additional pumps on the basis of the measured results of the pressure improvement and the beam loss suppression.
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WEPME036	Simulation of the Trajectory of Electrons in a Magnetron Sputtering System of TiN with CST Particle Studio	2341
	J. Wang, L. Fan, Y.Z. Hong, W.L. Liu, X.T. Pei, K. Tang, Y. Wang, W. Wei, Y.H. Xu, B. Zhang USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: National Nature Science Foundation of China under Grant Nos.11075157. In the process of magnetron sputtering deposition, electromagnetic fields have an important influence on the trajectory of particle movement and the properties of the TiN thin film in many cases. Even for simple geometries, the analytical prediction for charged particles trajectories is extremely cumbersome, so numerical simulations are essential to obtain a better understanding of the possible effects and helpful to optimize the design of experimental facility and experimental process. A software of CST PARTICLE STUDIOTM has been used to simulate the effect of magnetic and electric fields on electrons trajectories in the process of film coating. According to the simulation results, the improvement measures of the system design and experimental process have been achieved. The author put forward the improvement measures on film coating process according to the simulation results. The result shows that it is feasible and convenient to use three dimensional tool in the simulation of trajectory of electrons in a magnetron sputtering system.
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WEPME037	Monte Carlo Simulations of Synchrotron Radiation and Vacuum Performance of the Max IV Light Source	2344
SUSPSNE101	use link to see paper's listing under its alternate paper code
	M. Ady, R. Kersevan CERN, Geneva, Switzerland M.J. Grabski MAX-lab, Lund, Sweden
	In the MAX IV light-source in Lund, Sweden, the intense synchrotron radiation (SR) distributed along the ring generates important thermal and vacuum effects. By means of a Monte Carlo simulation package, which is currently developed at CERN, both thermal and vacuum effects are quantitatively analysed, in particular near the crotch absorbers and the surrounding NEG-coated vacuum chambers. Using SynRad+, the beam trajectory of the upstream bending magnet is calculated; SR photons are generated and traced through the geometry until their absorption. This allows an analysis of the incident power density on the absorber, and to calculate the photon induced outgassing. The results are imported to Molflow+, a Monte Carlo vacuum simulator that works in the molecular flow regime, and the pressure in the vacuum system and the saturation length of the NEG coating are determined using iterations.
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WEPME038	Introduction to the Latest Version of the Test-particle Monte Carlo Code Molflow+	2348
	M. Ady, R. Kersevan CERN, Geneva, Switzerland
	The Test-Particle Monte Carlo code Molflow+ is getting more and more attention from the scientific community needing detailed 3D calculations of vacuum in the molecular flow regime mainly, but not limited to, the particle accelerator field. Substantial changes, bug fixes, geometry-editing and modelling features, and computational speed improvements have been made to the code in the last couple of years. This paper will outline many of these new features, and show examples of applications to the design and analysis of vacuum systems at CERN and elsewhere.
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WEPME039	Leak Propagation Dynamics for the HIE-ISOLDE Superconducting Linac	2351
	G. Vandoni, M. Ady, M.A. Hermann, R. Kersevan, D.T. Ziemianski CERN, Geneva, Switzerland
	In order to cope with space limitations of existing infrastructure, the cryomodules of the HIE-Isolde superconducting linac feature a common insulation and beam vacuum, imposing the severe cleanliness standard of RF cavities to the whole cryostat. Protection of the linac vacuum against air-inrush from the three experimental stations through the HEBT lines relies on fast valves, triggered by fast cold cathode gauges. To evaluate the leak propagation velocity as a function of leak size and geometry of the lines, a computational and experimental investigation is being carried out at CERN. A 28 m long tube is equipped with strain gauges installed on thin-walled flanges, as well as fast reacting glow discharge and cold-cathode gauges. A leak is opened by the effect of a cutting pendulum, equipped with an accelerometer for data acquisition triggering, on a thin aluminium window followed by a calibrated orifice. The air inrush dynamics is simulated by Test-Particle Monte Carlo in the molecular regime and by Finite Elements fluid dynamics in the viscous regime.
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WEPME040	Development of Aluminium Vacuum Chambers for the LHC Experiments at CERN	2354
	M.A. Gallilee, P. Chiggiato, P. Costa Pinto, L.M.A. Ferreira, P. Lepeule, J. Perez Espinos, L. Prever-Loiri, A. Sapountzis CERN, Geneva, Switzerland
	Beam losses may cause activation of vacuum chamber walls, in particular those of the Large Hadron Collider (LHC) experiments. For the High Luminosity LHC, the activation of such vacuum chambers will increase. It is therefore necessary to use a vacuum chamber material which interacts less with the circulating beam. While beryllium is reserved for the collision point, a good compromise between cost, availability and transparency is obtained with aluminium alloys; such materials are a preferred choice with respect to austenitic stainless steel. Manufacturing a thin-wall aluminium vacuum chamber presents several challenges as the material grade needs to be machinable, weldable, leak-tight for small thicknesses, and able to withstand heating to 250°C for extended periods of time. This paper presents some of the technical challenges during the manufacture of these vacuum chambers and the methods for overcoming production difficulties, including surface treatments and NEG thin-film coating.
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WEPME041	Vacuum Acceptance Tests for the UHV Room Temperature Vacuum System of the LHC during LS1	2357
	G. Cattenoz, V. Baglin, G. Bregliozzi, D. Calegari, P. Chiggiato, J.E. Gallagher, A. Marraffa CERN, Geneva, Switzerland
	During the CERN Large Hadron Collider (LHC) first long shut down (LS1), a large number of vacuum tests are carried out on consolidated or newly fabricated pieces of equipment. In such a way, the vacuum compatibility is assessed before installation in the UHV system of the LHC. According to the equipment’s nature, the vacuum acceptance tests consist in functional checks, leak tests, outgassing rate measurements, evaluation of contaminants by Residual Gas Analysis (RGA), pumping speed measurements, and qualification of the sticking probability of Non-Evaporable-Getter coating. In this paper, the methods used for the tests and the acceptance criteria are described. A summary of the measured vacuum characteristics for the tested components is also given.
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WEPME042	The LHC Vacuum Pilot Sectors Project	2360
	B. Henrist, V. Baglin, G. Bregliozzi, P. Chiggiato CERN, Geneva, Switzerland
	The operation of the CERN Large Hadron Collider (LHC) at nominal beam parameters is expected for the next years (2015). Increased synchrotron-radiation stimulated-desorption and electron-cloud build-up are expected. A deep understanding of the interactions between the proton beams and the beampipe wall is mandatory to control the anticipated beam-induced pressure rise. A Vacuum Pilot Sector (VPS) has been designed to monitor the performance of the vacuum system with time. The VPS is installed along a double LHC room temperature vacuum sector (18 m long, 80 mm inner diameter beam pipes) and includes 8 standard modules, 1.4 m long each. Such modules are equipped with residual gas analysers, Bayard-Alpert gauges, photon and electron flux monitors, etc. The chosen modular approach opens the possibility of studying different configurations and implementing future modifications. This contribution will describe the apparatus, the control system designed to drive measurements and possible applications during the next LHC operational phase.
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WEPME043	Design and Qualification of Transparent Beam Vacuum Chamber Supports for the LHCb Experiment	2363
	J.L. Bosch, P. Chiggiato, C. Garion CERN, Geneva, Switzerland
	Beryllium beam vacuum chambers pass through the aperture of the large dipole magnet and particle acceptance region of the LHCb experiment, coaxial to the LHC beam. At the interior of the magnet, a system of rods and cables supports the chambers, holding them rigidly in place, in opposition to the vacuum forces caused by their conical geometry. In the scope of the current upgrade program, the steel and aluminium structural components are replaced by a newly designed system, making use of Beryllium, in addition to a number of organic materials, and are optimized for overall transparency to incident particles. Presented in this paper are the design criteria, along with the unique design developments carried out at CERN, and furthermore, a description of the technologies procured from industrial partners, specifically in obtaining the best solution for the cable components.
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WEPME044	LHC Experimental Beam Pipe Upgrade during LS1	2366
	G. Lanza, V. Baglin, G. Bregliozzi, P. Chiggiato CERN, Geneva, Switzerland
	The LHC experimental beam pipes are being improved during the ongoing long shutdown 1 (LS1). Several vacuum chambers have been tested and validated before their installation inside the detectors. The validation tests include: leak tightness, ultimate vacuum pressure, material outgassing rate, and residual gas composition. NEG coatings are assessed by hydrogen sticking probability measurement with the help of Monte Carlo simulations. In this paper the motivation for the beam pipe upgrade, the validation tests of the components and the results are presented and discussed.
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WEPME045	Assessment of New Components to be Integrated in the LHC Room Temperature Vacuum System	2369
	G. Bregliozzi, V. Baglin, P. Chiggiato CERN, Geneva, Switzerland
	Integration of new equipment in the long straight sections (LSS) of the LHC must be compatible with the TiZrV non-evaporable getter thin film that coats most of the 6-km-long room-temperature beam pipes. This paper focus on two innovative accelerator devices to be installed in the LSS during the long shutdown 1 (LS1): the beam gas vertex (BGV) and a beam bending experiment using crystal collimator (LUA9). The BGV necessitates a dedicated pressure bump, generated by local gas injection, in order to create the required rate of inelastic beam-gas interactions. The LAU9 experiments aims at improving beam cleaning efficiency with the use of a crystal collimator. New materials like fibre optics, piezoelectric components, and glues are proposed in the original design of the two devices. The integration feasibility of these set-ups in the LSS is presented. In particular outgassing tests of special components, X-rays photoelectron spectroscopy, analysis of NEG coating behaviour in presence of glues during bake-out, and pressure profile simulations will be presented.
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WEPME046	The HIE-Isolde Vacuum System	2372
	G. Vandoni, S. Blanchard, P. Chiggiato, K. Radwan CERN, Geneva, Switzerland
	The High Intensity and Energy Isolde (HIE-Isolde) project aims at increasing the energy and intensity of the radioactive ion beams (RIB) delivered by the present Rex-Isolde facility. Energy up to 10MeV/amu will be reached by a new post-accelerating, superconducting (SC) linac. Beam will be delivered via a HEBT to three experimental stations for nuclear physics. To keep the SC linac compact and avoid cold-warm transitions, the cryomodules feature a common beam and insulation vacuum. Radioactive ion beams require a hermetically sealed vacuum, with transfer of the effluents to the nuclear ventilation chimney. Hermetically sealed, dry, gas transfer vacuum pumps are preferred to gas binding pumps, for an optimized management of radioactive contamination risk during maintenance and intervention. The vacuum system of the SC-linac is isolated by two fast valves, triggered by fast reacting cold cathode gauges installed on the warm linac, the HEBT and the experimental stations. Rough pumping is distributed, while the HEBT turbomolecular pumps also share a common backing line. Slow pumpdown and ventilation of the cryomodules are studied to avoid particulate movement in the viscous regime.
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WEPME047	CERN Vacuum System Activities during the Long Shutdown 1: the LHC Beam Vacuum	2375
	V. Baglin, G. Bregliozzi, P. Chiggiato, J.M. Jimenez, G. Lanza CERN, Geneva, Switzerland
	After the Long Shutdown 1 (LS1) and the consolidation of the magnet bus bars, the CERN Large Hadron Collider (LHC) will operate with nominal beam parameters. Larger beam energy, beam intensities and luminosity are expected. Despite the very good performance of the beam vacuum system during the 2010-12 physics run (Run 1), some particular areas require attention for repair, consolidation and upgrade. Among the main activities, a large campaign aiming at the repair of the RF bridges of some vacuum modules is conducted. Moreover, consolidation of the cryogenic beam vacuum systems with burst disk for safety reasons is implemented. In addition, NEG cartridges, NEG coated inserts and new instruments for the vacuum system upgrade are installed. Besides these activities, repair, consolidation and upgrades of other beam equipment such as collimators, kickers and beam instrumentations are carried out. In this paper, the motivation and the description for such activities, together with the expected beam vacuum performance after LS1, are described in detail.
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WEPME048	Preliminary Design of the HiLumi-LHC Triplet Area Beam Screen	2378
	R. Kersevan, C. Garion, N. Kos CERN, Geneva, Switzerland
	The so-called beam screen (BS) is a proven solution for intercepting the thermal loads caused by the circulating beams in the cryogenically-cooled sections of the LHC and minimizing dynamic vacuum effects. The new triplet area foreseen for the HiLumi-LHC machine upgrade has the additional feature of needing internal tungsten shields to reduce the amount of collision debris which is deflected by the high-gradient triplet magnets towards the superconducting magnets' cold masses and coils. The very aggressive optics design, based on large beam separations, calls for a maximum of physical space to remain available to the counter rotating beams in the common BS. This places severe constraints to the fabrication and installation tolerances of the BS itself, in addition to affecting the design and routing of the cryogenic lines in the area. The latest version of the BS design will be shown and discussed, together with future plans for testing materials, fabrication procedures, and installation. * The HiLumi LHC Design Study is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404
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WEPME049	Coupled Simulations of the Synchrotron Radiation and Induced Desorption Pressure Profiles for the HiLumi-LHC Triplet Area and Interaction Points	2381
	R. Kersevan, V. Baglin, G. Bregliozzi CERN, Geneva, Switzerland
	The HiLumi-LHC machine upgrade has officially started as an approved LHC project (see dedicated presentations at this conference on the subject). One important feature of the upgrade is the installation of very high-gradient triplet magnets for focusing the beams at the collision points of the two high-luminosity detectors ATLAS and CMS. Other important topics are new superconducting D1 magnets, installation of crab cavities, and re-shuffling of the dispersion suppression area. Based on the current magnetic lattice set-up and beam orbits, a detailed study of the emission of synchrotron radiation (SR) and related photon-induced desorption (PID) has been carried out. A significant amount of SR photons are generated by the two off-axis beams in the common vacuum chamber of the triplet area, about 57 m in length. Ray-tracing Montecarlo codes SYNRAD⁺ and Molflow+ have been employed in this study. The related PID pressure profiles will be shown, together with simulations using the code VASCO for the analysis of beam losses and background in the detectors, including electron cloud effects. () The HiLumi LHC Design Study is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404*
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WEPME050	High Frequency Electromagnetic Characterization of NEG properties for the CLIC Damping Rings	2384
SUSPSNE103	use link to see paper's listing under its alternate paper code
	E. Koukovini-Platia, G. Rumolo, C. Zannini CERN, Geneva, Switzerland
	Coating materials will be used in the CLIC damping rings (DR) to suppress two-stream effects. In particular, NEG coating is necessary to suppress fast beam ion instabilities in the electron damping ring (EDR). The electromagnetic (EM) characterization of the material properties up to high frequencies is required for the impedance modeling of the CLIC DR components. The EM properties for frequencies of few GHz are determined with the waveguide method, based on a combination of experimental measurements of the complex transmission coefficient S21 and CST 3D EM simulations. The results obtained from a NEG coated copper (Cu) waveguide are presented in this paper.
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WEPME051	Development of the TPS Vacuum Interlock and Monitor Systems	2387
	Y.C. Yang, B.Y. Chen, J.-R. Chen, Z.W. Chen, J. -Y. Chuang, G.-Y. Hsiung, T.Y. Lee NSRRC, Hsinchu, Taiwan
	The vacuum interlock and monitor systems of Taiwan Photon Source are designed to maintain the ultra-high vacuum condition and to protect the vacuum devices. The pressure readings of ionization gauges are taken as the judgment logic to control the opening and closing of sector gate valves so as to protect the ultra-high vacuum condition. Monitors of the water-cooling system and the chamber temperature serve to protect vacuum devices from radiation hazards. The preparation, installation and status of the interlock and monitor systems are presented in this paper.
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WEPME052	The Installation of TPS Booster Vacuum System	2390
	C.M. Cheng, B.Y. Chen, J.-R. Chen, G.-Y. Hsiung, S-N. Hsu, T.Y. Lee, Y.C. Yang NSRRC, Hsinchu, Taiwan J.-R. Chen National Tsing Hua University, Hsinchu, Taiwan
	The booster of Taiwan Photon Source (TPS) is designed for 3GeV full energy injection ramped up from 150MeV. It is a synchrotron accelerator of 496.8m. The major vacuum system is elliptical tube made of 304 stainless steel. The inner cross section is 35*20 mm with 0.7 mm thickness. The elliptical tubes were chemical cleaned and ozonated water cleaned before installation. The bending tube was assembled and aligned into dipole magnet at laboratory. The BPM support and pumping chamber support was aligned with 0.3 mm deviation. The BPM chamber and pumping chamber was assembled firstly. The elliptical tube and bellows was installed to connect BPM, pumping chamber and bending chamber. The cold cathode gauge and TMP was mounted on pumping chamber. The pressure data and residual gas analysis will be described in the paper.
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WEPME054	Design and Fabrication of the Novel-type Ceramic Chamber	2393
	L.H. Wu, C.K. Chan, J.-R. Chen, G.-Y. Hsiung, S-N. Hsu, T.Y. Lee NSRRC, Hsinchu, Taiwan J.-R. Chen National Tsing Hua University, Hsinchu, Taiwan
	A ceramic chamber of novel type has been designed and fabricated. The uniformity of its inner thin film of deposited metal is improved to have a thickness error about 1 %. The average straightness error of the chamber (length 550 mm) is developed to be less than 55 μm. To fabricate the ceramic chamber of novel type, we first cleaned and joined the two halves; the metal films were deposited by sputtering. These two halves were next sealed with a glass powder colloid to become a ceramic tube. The rate of outgassing of this colloid is 3.57×10^-12 Torr L s⁻¹ cm^-2 after baking. The ceramic tube was connected to a stainless-steel flange with the aid of a glass powder colloid and TIG welding. This ceramic test chamber will be installed in the experimental system to analyze the residual gas.
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WEPME055	Residual Gas in the 14 m-long Aluminium Vacuum System of the Storage Ring of Taiwan Photon Source: toward Ultra-high Vacuum	2396
	T.Y. Lee, C.K. Chan, C.H. Chang, C.-C. Chang, S.W. Chang, Y.P. Chang, B.Y. Chen, J.-R. Chen, Z.W. Chen, C.M. Cheng, Y.T. Cheng, G.-Y. Hsiung, S-N. Hsu, H.P. Hsueh, C.S. Huang, Y.T. Huang, L.H. Wu, Y.C. Yang NSRRC, Hsinchu, Taiwan
	In the Taiwan Photon Source project, the storage ring includes 24 sectors (each of length 14 m) of an aluminium vacuum chamber system. The design, manufacture, cleaning, welding and assembly of the vacuum components were undertaken by the NSRRC vacuum group. The ultimate objective is to attain a leak-tight, ultra-high vacuum and a vacuum system with a small rate of outgassing. In this work, we used a residual-gas analyzer (RGA) to analyze the variation of residual gas during proceeding toward ultra-high vacuum. This process, which led the pressure down to ~10^-11 torr, includes baking, operation of ion pumps, degassing of hot cathode gauges and activation of NEG pumps. When a sufficiently small low pressure is attained, the ion pumps are turned off to test the building up of pressure. The outgassing property and the variation of the residual gas of the aluminium chamber and the ion pumps can be measured.
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WEPME056	Further Optimisation of NEG Coatings for Accelerator Beam Chamber	2399
	O.B. Malyshev, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The non-evaporable getter (NEG) coating, invented at CERN in 90s, is used nowadays in many accelerators around the world. The main advantages of using NEG coatings are evenly distributed pumping speed, low thermal outgassing rates and low photon and electron stimulated gas desorption. The only downside of the NEG is its selective pumping: it pumps H2, CO, CO2 and some other gas species, but does not pump noble gases and hydrocarbons. However, in the accelerators where NEG coating could be beneficial, there is synchrotron radiation and photoelectrons that bombard vacuum chamber walls, it was found in our study that hydrocarbons can be pumped by NEG coating under electron and, most likely, photon bombardment. The detail and the results of this study are reported in this paper.
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WEPME057	The Secondary Electron Yield from Transition Metals	2403
	S. Wang, M.D. Cropper Loughborough University, Loughborough, Leicestershire, United Kingdom O.B. Malyshev, E.A. Seddon, R. Valizadeh, S. Wang STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Non-evaporable getter thin films, which are currently being used in the ultra-high vacuum system of the Large Hadron Collider, normally consist of Ti, Zr and V, deposited by physical vapour deposition. In this study, the secondary electron yield (SEY) of bulk Ti, Zr, V and Hf have been investigated as a function of electron conditioning. The maximum SEYs of as-received Ti, Zr, V and Hf, are respectively 1.96, 2.34, 1.72 and 2.32, these reduce to 1.14, 1.13, 1.44 and 1.18 after electron conditioning. Surface chemical composition was studied by X-ray photoelectron spectroscopy which revealed that surface conditioning by electron bombardment promotes the growth of a thin carbon layer on the surface and consequently reduces the SEY of the surface as a function of electron dose. Heating a vanadium sample to 250°C resulted in diffusion of oxygen into the bulk and induced formation of metal carbide at the surface. However, the SEY stays the same even after heat-induced surface chemistry modification. Prolonged electron conditioning increases the surface oxygen but the surface is still predominantly covered with a thin graphitic layer and hence the SEY stays approximately constant.
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WEPME059	Conceptual Design of a Storage Ring Vacuum System Compatible with Implementation of a Seven Bend Achromat Lattice at the APS	2409
	B.K. Stillwell, B. Brajuskovic, H. Cease, D.L. Fallin, J. R. Noonan, M.M. O'Neill ANL, Argonne, Ilinois, USA
	A conceptual design is presented for a storage ring vacuum system at the Advanced Photon Source (APS) which is compatible with a multi-bend achromat (MBA) lattice under development for the APS Upgrade (APS-U) project [1]. Together, the interface with the magnets, required quantity and stability of beam position monitors, synchrotron radiation loading, and beam physics requirements place a demanding set of constraints on the vacuum system design. However, the requirements can be satisfied with a hybrid system which combines conventional extruded aluminum chambers incorporating “antechambers” with a variety of simpler tubular chambers made variously of copper-plated stainless steel, NEG-coated copper, and bare aluminum. This hybrid system has advantages over an all NEG-coated copper system with regard to overall project risk, required installation time, and maintainability.
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WEPRI043	Implementation of Carbon Thin Film Coatings in the Super Proton Synchrotron (SPS) for Electron Cloud Mitigation	2574
	P. Costa Pinto, T.C. Basso, A. Bellunato, P. Edwards, M. Mensi, A. Sublet, M. Taborelli CERN, Geneva, Switzerland
	Low Secondary Electron Yield (SEY) carbon thin films get rid of electron multipacting in accelerator beam pipes. Two magnetic cells of the SPS were coated with such material and installed. In total more than forty vacuum vessels and magnet interconnections were treated. The feasibility of the coating process was validated. The performance of the carbon thin film will be tested with LHC nominal beams after the end of the long shutdown 1. Particular attention will be drawn to the long term behaviour. This paper presents the sputtering techniques used to coat the different components; their characterization (SEY measurements on coupons, RF multipacting tests and pump down curves); and the technology to etch the carbon film in case of a faulty coating. The strategy to coat the entire SPS will also be exposed.
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Paper

Title

Page

CERN Vacuum System Activities during the Long Shutdown 1: The LHC’s injector chain.

2291

J.A. Ferreira Somoza, P. Chiggiato
CERN, Geneva, Switzerland

During the long shutdown 1 (LS1), several maintenance, consolidation and upgrade activities have been carried out in LHC’s injector chain. Each machine has specific vacuum requirements and different history, which determine the present status of the vacuum components, their maintenance and consolidation needs. The present work presents the priorities agreed at the beginning of the LS1 period and their implementation. Of particular relevance are the interventions in radioactive controlled areas where several leaks due to stress corrosions stopped the operations in the past years. The strategy to reduce the collective dose is presented, in particular the use of remote controlled robots. An important part of the work performed during this period involves supporting other teams (acceptance tests, new equipment installation, etc.). Finally, as a result of the LS1 experience, a medium to long term strategy is depicted, focusing on the preparation of the next shutdown (LS2) and the integration of LINAC4 in the injector chain during the same period.

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WEPME025

Design and Performance of Ultimate Vacuum System for the AREAL Test Facility

2311

A.A. Gevorgyan, V.S. Avagyan, B. Grigoryan, T.H. Mkrtchyan, A.S. Simonyan, V. V. Vardanyan
CANDLE SRI, Yerevan, Armenia

The design specification of the AREAL test facility require the residual pressure at the level of 1nTorr with beam through entire vacuum chamber. We present the main features of the vacuum system, including the design and fabrication peculiarities of the dedicated components like dipole magnet stainless steel vacuum chamber and the cubes for beam diagnostic stations. The philosophy and instrumentation of the vacuum system are discussed.

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WEPME026

Layout of the Vacuum System for a New ESRF Storage Ring

2314

M. Hahn, J.C. Biasci, H.P. Marques
ESRF, Grenoble, France

The proposed 7-bend achromat lattice for the new 6 GeV electron storage ring of the European Synchrotron Radiation Facility imposes a change of the entire vacuum system. Small bore magnets will require low conductance vacuum chambers. Conventional vacuum pumps will have to be assisted by distributed pumping provided by Non-Evaporable Getter (NEG) coating. The time constraints for design, prototyping, pre-assembly, installation and commissioning of the new systems require simple solutions and the use of existing expertise where possible. In this paper the draft layout of the vacuum system will be explained, information about the expected dynamic pressure distribution and conditioning will be given. Some technical solutions to resolve specific issues arising from the small vacuum chamber dimensions and the dense arrangement of components are described.

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WEPME028

Systematic Measurement of the Pumping Capabilities of Cryogenic Surfaces

2317

SUSPSNE102

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F. Chill, O.K. Kester
IAP, Frankfurt am Main, Germany
L.H.J. Bozyk, O.K. Kester, P.J. Spiller
GSI, Darmstadt, Germany

The quality of the beam vacuum is crucial for the stable operation of synchrotrons with high intensity heavy ions. Cryogenic surfaces are capable of pumping residual gases by cryocondensation until the saturated vapor pressure (SVP) is reached. Even at LHe temperatures the SVP of hydrogen is too high. If the surface coverage is sufficiently low, residual gas can also be bound by cryosorption, yielding in acceptable low pressures. These pumping capabilities can be described by two parameters, both dependent on surface temperature and coverage: The sticking probability (SP), that is the chance of an impinging gas particle to be bound, and the mean sojourn time (MST) of a particle on the surface. To acquire these parameters, an experimental setup is currently built at GSI. It consists of a cryogenic chamber, cooled by a cold head and a warm part with vacuum diagnostics and gas inlet. It allows monitoring the pumping speed and also the equilibrium pressure of the cryogenic part from which the SP and the MST can be deducted. The results will be used to further improve the accuracy of the dynamic vacuum simulations in cryogenic areas of particle accelerators.

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WEPME029

Development of a Field Emitter-based Extractor Gauge for the Operation in Cryogenic Vacuum Environments

2320

M. Lotz, O.K. Kester, St. Wilfert
GSI, Darmstadt, Germany

This paper presents an investigation of a CNT emitter-based extractor gauge which is designed for pressure reading in cryogenic ultra-high vacuum systems. The results show that the modified gauge works well in both room temperature and cryogenic vacuum environments. Furthermore, it could be demonstrated that the modified gauge responds much more sensitive to small pressure fluctuations in cryogenic environments than the same gauge type having a hot-filament cathode.

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WEPME030

Design and Construction of a Prototype Sputter ion Pump in ILSF

2323

O. Seify, H. Ghasem, S. Kashani, J. Rahighi
ILSF, Tehran, Iran
H. Ghasem
IPM, Tehran, Iran

Design and construction process of special kind of sputter ion pump is described briefly in this paper. In order to investigate the optimization of effective parameters in choosing and designing ILSF ion pumps, this pump has been designed and manufactured. By optimizing some parameters such as dimension and shape of penning cells, anode voltage, magnetic field and internal structure of pump, it is possible to significantly decrease the cost of construction and operation of synchrotron vacuum system. One of the most important advantages of this design, is that the initial parameters and finally internal structure of the prototype pump are changeable easily. The effect of parameters like anode voltage, magnetic field etc. on pumping speed and final pressure are described. With the existing optimization it is expected that an ultimate pressure of 1x10^-11 Torr could be achieved.

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WEPME032

Detailed Investigation of the Low Energy Secondary Electron Yield of Technical Cu and its Relevance for LHC

2329

R. Cimino, L.A. Gonzalez, A.L. Romano
INFN/LNF, Frascati (Roma), Italy
R. Cimino, G. Iadarola, G. Rumolo
CERN, Geneva, Switzerland
R. Larciprete
ISM-CNR, Rome, Italy

The detailed study of the Secondary Electron Yield (SEY) of technical Cu for very low electron landing energies (from 0 to 30 eV) is very important for electron cloud build up in high intensity accelerators and in many other fields of research. However, this question has been rarely addressed due to the intrinsic experimental complexity to control very low energy electrons. Furthermore, several results published in the past have been recently questioned for allegedly suffering from experimental systematics. In this paper, we critically review the experimental method used to study low energy SEY and define more precise energy regions, in which the experimental data can be considered valid. The new SEY curves are then fed into e-cloud simulation codes to address their impact for electron cloud predictions in the LHC.

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WEPME033

Search for New e-cloud Mitigator Materials for High Intensity Particle Accelerators

2332

R. Cimino, S.T. O'connor, A.L. Romano
INFN/LNF, Frascati (Roma), Italy
V. Baglin, G. Bregliozzi, R. Cimino
CERN, Geneva, Switzerland
M.R. Masullo
INFN-Napoli, Napoli, Italy
S. Petracca, A. Stabile
INFN-Salerno, Baronissi, Salerno, Italy

Electron cloud is an ubiquitous effect in positively charged particle accelerators and has been observed to induce unwanted detrimental impacts on beam quality, stability, vacuum etc. A great effort has been recently devoted to the search of new material morphology and/or coatings which can intrinsically mitigate beam instabilities deriving from electron cloud effects. In this context, we present some characterization of Cu foams, available from the market, and their qualification in terms of their vacuum behavior, impedance, secondary electron yield, gas desorption etc. More experimental effort is required to finally qualify foams as a mature technology to be integrated in accelerator environments. But, our preliminary results suggests that, when compatible with geometrical constrains, Cu foams can be utilized when low desorption yields are required and as e-cloud moderator in future particles accelerators.

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WEPME034

Soft X-ray Reflectivity and Photoelectron Yield of Technical Materials: Experimental Input for Instability Simulations in High Intensity Accelerators

2335

R. Cimino
INFN/LNF, Frascati (Roma), Italy
R. Cimino
CERN, Geneva, Switzerland
F. Schäfers
HZB, Berlin, Germany

High luminosity particle accelerators can suffer from serious performance drop or limitations due to interaction of the synchrotron radiation produced by the accelerator itself with the accelerator walls. Such interaction may produce a number of photoelectrons, that can either seed electron cloud related instabilities and/or interact anyway with the beam itself, potentially causing its deterioration. To correctly take these effects into account simulation codes depends on the realistic knowledge of Reflectivity and Photoelectron Yield of technical material. In this work we present relevant experimental data for some of the mostly used technical surfaces in accelerators.

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WEPME035

Beam Loss Suppression by Improvement of Vacuum System in J-PARC RCS

2338

J. Kamiya, M. Kinsho, S. Noshiroya, K. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan

In high power beam accelerators, pressure of the beam line directly affects the amount of the beam loss. For example, in the early 1970’s in CERN’s Intersecting Storage Ring (ISR), the ion-induced pressure bump produced the fall-off of the beam current. 3GeV synchrotron (RCS) in J-PARC is no exception. RCS is one of the most high power beam accelerators in the world. It aims the 1 MW beam power, which corresponds to the average and peak beam current of 333 uA and about 10 A, respectively. In the present stage, the injection line called L3BT line (Linac to 3GeV Beam Transport line), is the section, where the pressure notably produces the beam loss. In this line, H⁻ beam from Linac was converted to H⁰ by charge stripping due to the interaction between H⁻ beam and the residual gas molecules. Such H⁰ was not bended by the injection septum magnets and directly hit the vacuum wall. We decided to add the vacuum pumps in this line to reduce the residual gas molecules. We will present the effectivity of the additional pumps on the basis of the measured results of the pressure improvement and the beam loss suppression.

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WEPME036

Simulation of the Trajectory of Electrons in a Magnetron Sputtering System of TiN with CST Particle Studio

2341

J. Wang, L. Fan, Y.Z. Hong, W.L. Liu, X.T. Pei, K. Tang, Y. Wang, W. Wei, Y.H. Xu, B. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: National Nature Science Foundation of China under Grant Nos.11075157.
In the process of magnetron sputtering deposition, electromagnetic fields have an important influence on the trajectory of particle movement and the properties of the TiN thin film in many cases. Even for simple geometries, the analytical prediction for charged particles trajectories is extremely cumbersome, so numerical simulations are essential to obtain a better understanding of the possible effects and helpful to optimize the design of experimental facility and experimental process. A software of CST PARTICLE STUDIOTM has been used to simulate the effect of magnetic and electric fields on electrons trajectories in the process of film coating. According to the simulation results, the improvement measures of the system design and experimental process have been achieved. The author put forward the improvement measures on film coating process according to the simulation results. The result shows that it is feasible and convenient to use three dimensional tool in the simulation of trajectory of electrons in a magnetron sputtering system.

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WEPME037

Monte Carlo Simulations of Synchrotron Radiation and Vacuum Performance of the Max IV Light Source

2344

SUSPSNE101

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M. Ady, R. Kersevan
CERN, Geneva, Switzerland
M.J. Grabski
MAX-lab, Lund, Sweden

In the MAX IV light-source in Lund, Sweden, the intense synchrotron radiation (SR) distributed along the ring generates important thermal and vacuum effects. By means of a Monte Carlo simulation package, which is currently developed at CERN, both thermal and vacuum effects are quantitatively analysed, in particular near the crotch absorbers and the surrounding NEG-coated vacuum chambers. Using SynRad+, the beam trajectory of the upstream bending magnet is calculated; SR photons are generated and traced through the geometry until their absorption. This allows an analysis of the incident power density on the absorber, and to calculate the photon induced outgassing. The results are imported to Molflow+, a Monte Carlo vacuum simulator that works in the molecular flow regime, and the pressure in the vacuum system and the saturation length of the NEG coating are determined using iterations.

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WEPME038

Introduction to the Latest Version of the Test-particle Monte Carlo Code Molflow+

2348

M. Ady, R. Kersevan
CERN, Geneva, Switzerland

The Test-Particle Monte Carlo code Molflow+ is getting more and more attention from the scientific community needing detailed 3D calculations of vacuum in the molecular flow regime mainly, but not limited to, the particle accelerator field. Substantial changes, bug fixes, geometry-editing and modelling features, and computational speed improvements have been made to the code in the last couple of years. This paper will outline many of these new features, and show examples of applications to the design and analysis of vacuum systems at CERN and elsewhere.

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WEPME039

Leak Propagation Dynamics for the HIE-ISOLDE Superconducting Linac

2351

G. Vandoni, M. Ady, M.A. Hermann, R. Kersevan, D.T. Ziemianski
CERN, Geneva, Switzerland

In order to cope with space limitations of existing infrastructure, the cryomodules of the HIE-Isolde superconducting linac feature a common insulation and beam vacuum, imposing the severe cleanliness standard of RF cavities to the whole cryostat. Protection of the linac vacuum against air-inrush from the three experimental stations through the HEBT lines relies on fast valves, triggered by fast cold cathode gauges. To evaluate the leak propagation velocity as a function of leak size and geometry of the lines, a computational and experimental investigation is being carried out at CERN. A 28 m long tube is equipped with strain gauges installed on thin-walled flanges, as well as fast reacting glow discharge and cold-cathode gauges. A leak is opened by the effect of a cutting pendulum, equipped with an accelerometer for data acquisition triggering, on a thin aluminium window followed by a calibrated orifice. The air inrush dynamics is simulated by Test-Particle Monte Carlo in the molecular regime and by Finite Elements fluid dynamics in the viscous regime.

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WEPME040

Development of Aluminium Vacuum Chambers for the LHC Experiments at CERN

2354

M.A. Gallilee, P. Chiggiato, P. Costa Pinto, L.M.A. Ferreira, P. Lepeule, J. Perez Espinos, L. Prever-Loiri, A. Sapountzis
CERN, Geneva, Switzerland

Beam losses may cause activation of vacuum chamber walls, in particular those of the Large Hadron Collider (LHC) experiments. For the High Luminosity LHC, the activation of such vacuum chambers will increase. It is therefore necessary to use a vacuum chamber material which interacts less with the circulating beam. While beryllium is reserved for the collision point, a good compromise between cost, availability and transparency is obtained with aluminium alloys; such materials are a preferred choice with respect to austenitic stainless steel. Manufacturing a thin-wall aluminium vacuum chamber presents several challenges as the material grade needs to be machinable, weldable, leak-tight for small thicknesses, and able to withstand heating to 250°C for extended periods of time. This paper presents some of the technical challenges during the manufacture of these vacuum chambers and the methods for overcoming production difficulties, including surface treatments and NEG thin-film coating.

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WEPME041

Vacuum Acceptance Tests for the UHV Room Temperature Vacuum System of the LHC during LS1

2357

G. Cattenoz, V. Baglin, G. Bregliozzi, D. Calegari, P. Chiggiato, J.E. Gallagher, A. Marraffa
CERN, Geneva, Switzerland

During the CERN Large Hadron Collider (LHC) first long shut down (LS1), a large number of vacuum tests are carried out on consolidated or newly fabricated pieces of equipment. In such a way, the vacuum compatibility is assessed before installation in the UHV system of the LHC. According to the equipment’s nature, the vacuum acceptance tests consist in functional checks, leak tests, outgassing rate measurements, evaluation of contaminants by Residual Gas Analysis (RGA), pumping speed measurements, and qualification of the sticking probability of Non-Evaporable-Getter coating. In this paper, the methods used for the tests and the acceptance criteria are described. A summary of the measured vacuum characteristics for the tested components is also given.

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WEPME042

The LHC Vacuum Pilot Sectors Project

2360

B. Henrist, V. Baglin, G. Bregliozzi, P. Chiggiato
CERN, Geneva, Switzerland

The operation of the CERN Large Hadron Collider (LHC) at nominal beam parameters is expected for the next years (2015). Increased synchrotron-radiation stimulated-desorption and electron-cloud build-up are expected. A deep understanding of the interactions between the proton beams and the beampipe wall is mandatory to control the anticipated beam-induced pressure rise. A Vacuum Pilot Sector (VPS) has been designed to monitor the performance of the vacuum system with time. The VPS is installed along a double LHC room temperature vacuum sector (18 m long, 80 mm inner diameter beam pipes) and includes 8 standard modules, 1.4 m long each. Such modules are equipped with residual gas analysers, Bayard-Alpert gauges, photon and electron flux monitors, etc. The chosen modular approach opens the possibility of studying different configurations and implementing future modifications. This contribution will describe the apparatus, the control system designed to drive measurements and possible applications during the next LHC operational phase.

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WEPME043

Design and Qualification of Transparent Beam Vacuum Chamber Supports for the LHCb Experiment

2363

J.L. Bosch, P. Chiggiato, C. Garion
CERN, Geneva, Switzerland

Beryllium beam vacuum chambers pass through the aperture of the large dipole magnet and particle acceptance region of the LHCb experiment, coaxial to the LHC beam. At the interior of the magnet, a system of rods and cables supports the chambers, holding them rigidly in place, in opposition to the vacuum forces caused by their conical geometry. In the scope of the current upgrade program, the steel and aluminium structural components are replaced by a newly designed system, making use of Beryllium, in addition to a number of organic materials, and are optimized for overall transparency to incident particles. Presented in this paper are the design criteria, along with the unique design developments carried out at CERN, and furthermore, a description of the technologies procured from industrial partners, specifically in obtaining the best solution for the cable components.

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WEPME044

LHC Experimental Beam Pipe Upgrade during LS1

2366

G. Lanza, V. Baglin, G. Bregliozzi, P. Chiggiato
CERN, Geneva, Switzerland

The LHC experimental beam pipes are being improved during the ongoing long shutdown 1 (LS1). Several vacuum chambers have been tested and validated before their installation inside the detectors. The validation tests include: leak tightness, ultimate vacuum pressure, material outgassing rate, and residual gas composition. NEG coatings are assessed by hydrogen sticking probability measurement with the help of Monte Carlo simulations. In this paper the motivation for the beam pipe upgrade, the validation tests of the components and the results are presented and discussed.

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WEPME045

Assessment of New Components to be Integrated in the LHC Room Temperature Vacuum System

2369

G. Bregliozzi, V. Baglin, P. Chiggiato
CERN, Geneva, Switzerland

Integration of new equipment in the long straight sections (LSS) of the LHC must be compatible with the TiZrV non-evaporable getter thin film that coats most of the 6-km-long room-temperature beam pipes. This paper focus on two innovative accelerator devices to be installed in the LSS during the long shutdown 1 (LS1): the beam gas vertex (BGV) and a beam bending experiment using crystal collimator (LUA9). The BGV necessitates a dedicated pressure bump, generated by local gas injection, in order to create the required rate of inelastic beam-gas interactions. The LAU9 experiments aims at improving beam cleaning efficiency with the use of a crystal collimator. New materials like fibre optics, piezoelectric components, and glues are proposed in the original design of the two devices. The integration feasibility of these set-ups in the LSS is presented. In particular outgassing tests of special components, X-rays photoelectron spectroscopy, analysis of NEG coating behaviour in presence of glues during bake-out, and pressure profile simulations will be presented.

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WEPME046

The HIE-Isolde Vacuum System

2372

G. Vandoni, S. Blanchard, P. Chiggiato, K. Radwan
CERN, Geneva, Switzerland

The High Intensity and Energy Isolde (HIE-Isolde) project aims at increasing the energy and intensity of the radioactive ion beams (RIB) delivered by the present Rex-Isolde facility. Energy up to 10MeV/amu will be reached by a new post-accelerating, superconducting (SC) linac. Beam will be delivered via a HEBT to three experimental stations for nuclear physics. To keep the SC linac compact and avoid cold-warm transitions, the cryomodules feature a common beam and insulation vacuum. Radioactive ion beams require a hermetically sealed vacuum, with transfer of the effluents to the nuclear ventilation chimney. Hermetically sealed, dry, gas transfer vacuum pumps are preferred to gas binding pumps, for an optimized management of radioactive contamination risk during maintenance and intervention. The vacuum system of the SC-linac is isolated by two fast valves, triggered by fast reacting cold cathode gauges installed on the warm linac, the HEBT and the experimental stations. Rough pumping is distributed, while the HEBT turbomolecular pumps also share a common backing line. Slow pumpdown and ventilation of the cryomodules are studied to avoid particulate movement in the viscous regime.

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WEPME047

CERN Vacuum System Activities during the Long Shutdown 1: the LHC Beam Vacuum

2375

V. Baglin, G. Bregliozzi, P. Chiggiato, J.M. Jimenez, G. Lanza
CERN, Geneva, Switzerland

After the Long Shutdown 1 (LS1) and the consolidation of the magnet bus bars, the CERN Large Hadron Collider (LHC) will operate with nominal beam parameters. Larger beam energy, beam intensities and luminosity are expected. Despite the very good performance of the beam vacuum system during the 2010-12 physics run (Run 1), some particular areas require attention for repair, consolidation and upgrade. Among the main activities, a large campaign aiming at the repair of the RF bridges of some vacuum modules is conducted. Moreover, consolidation of the cryogenic beam vacuum systems with burst disk for safety reasons is implemented. In addition, NEG cartridges, NEG coated inserts and new instruments for the vacuum system upgrade are installed. Besides these activities, repair, consolidation and upgrades of other beam equipment such as collimators, kickers and beam instrumentations are carried out. In this paper, the motivation and the description for such activities, together with the expected beam vacuum performance after LS1, are described in detail.

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WEPME048

Preliminary Design of the HiLumi-LHC Triplet Area Beam Screen

2378

R. Kersevan, C. Garion, N. Kos
CERN, Geneva, Switzerland

The so-called beam screen (BS) is a proven solution for intercepting the thermal loads caused by the circulating beams in the cryogenically-cooled sections of the LHC and minimizing dynamic vacuum effects. The new triplet area foreseen for the HiLumi-LHC machine upgrade has the additional feature of needing internal tungsten shields to reduce the amount of collision debris which is deflected by the high-gradient triplet magnets towards the superconducting magnets' cold masses and coils. The very aggressive optics design, based on large beam separations, calls for a maximum of physical space to remain available to the counter rotating beams in the common BS. This places severe constraints to the fabrication and installation tolerances of the BS itself, in addition to affecting the design and routing of the cryogenic lines in the area. The latest version of the BS design will be shown and discussed, together with future plans for testing materials, fabrication procedures, and installation.
* The HiLumi LHC Design Study is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404

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WEPME049

Coupled Simulations of the Synchrotron Radiation and Induced Desorption Pressure Profiles for the HiLumi-LHC Triplet Area and Interaction Points

2381

R. Kersevan, V. Baglin, G. Bregliozzi
CERN, Geneva, Switzerland

The HiLumi-LHC machine upgrade has officially started as an approved LHC project (see dedicated presentations at this conference on the subject). One important feature of the upgrade is the installation of very high-gradient triplet magnets for focusing the beams at the collision points of the two high-luminosity detectors ATLAS and CMS. Other important topics are new superconducting D1 magnets, installation of crab cavities, and re-shuffling of the dispersion suppression area. Based on the current magnetic lattice set-up and beam orbits, a detailed study of the emission of synchrotron radiation (SR) and related photon-induced desorption (PID) has been carried out. A significant amount of SR photons are generated by the two off-axis beams in the common vacuum chamber of the triplet area, about 57 m in length. Ray-tracing Montecarlo codes SYNRAD⁺ and Molflow+ have been employed in this study. The related PID pressure profiles will be shown, together with simulations using the code VASCO for the analysis of beam losses and background in the detectors, including electron cloud effects.
(*) The HiLumi LHC Design Study is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404

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WEPME050

High Frequency Electromagnetic Characterization of NEG properties for the CLIC Damping Rings

2384

SUSPSNE103

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E. Koukovini-Platia, G. Rumolo, C. Zannini
CERN, Geneva, Switzerland

Coating materials will be used in the CLIC damping rings (DR) to suppress two-stream effects. In particular, NEG coating is necessary to suppress fast beam ion instabilities in the electron damping ring (EDR). The electromagnetic (EM) characterization of the material properties up to high frequencies is required for the impedance modeling of the CLIC DR components. The EM properties for frequencies of few GHz are determined with the waveguide method, based on a combination of experimental measurements of the complex transmission coefficient S21 and CST 3D EM simulations. The results obtained from a NEG coated copper (Cu) waveguide are presented in this paper.

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WEPME051

Development of the TPS Vacuum Interlock and Monitor Systems

2387

Y.C. Yang, B.Y. Chen, J.-R. Chen, Z.W. Chen, J. -Y. Chuang, G.-Y. Hsiung, T.Y. Lee
NSRRC, Hsinchu, Taiwan

The vacuum interlock and monitor systems of Taiwan Photon Source are designed to maintain the ultra-high vacuum condition and to protect the vacuum devices. The pressure readings of ionization gauges are taken as the judgment logic to control the opening and closing of sector gate valves so as to protect the ultra-high vacuum condition. Monitors of the water-cooling system and the chamber temperature serve to protect vacuum devices from radiation hazards. The preparation, installation and status of the interlock and monitor systems are presented in this paper.

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WEPME052

The Installation of TPS Booster Vacuum System

2390

C.M. Cheng, B.Y. Chen, J.-R. Chen, G.-Y. Hsiung, S-N. Hsu, T.Y. Lee, Y.C. Yang
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

The booster of Taiwan Photon Source (TPS) is designed for 3GeV full energy injection ramped up from 150MeV. It is a synchrotron accelerator of 496.8m. The major vacuum system is elliptical tube made of 304 stainless steel. The inner cross section is 35*20 mm with 0.7 mm thickness. The elliptical tubes were chemical cleaned and ozonated water cleaned before installation. The bending tube was assembled and aligned into dipole magnet at laboratory. The BPM support and pumping chamber support was aligned with 0.3 mm deviation. The BPM chamber and pumping chamber was assembled firstly. The elliptical tube and bellows was installed to connect BPM, pumping chamber and bending chamber. The cold cathode gauge and TMP was mounted on pumping chamber. The pressure data and residual gas analysis will be described in the paper.

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WEPME054

Design and Fabrication of the Novel-type Ceramic Chamber

2393

L.H. Wu, C.K. Chan, J.-R. Chen, G.-Y. Hsiung, S-N. Hsu, T.Y. Lee
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

A ceramic chamber of novel type has been designed and fabricated. The uniformity of its inner thin film of deposited metal is improved to have a thickness error about 1 %. The average straightness error of the chamber (length 550 mm) is developed to be less than 55 μm. To fabricate the ceramic chamber of novel type, we first cleaned and joined the two halves; the metal films were deposited by sputtering. These two halves were next sealed with a glass powder colloid to become a ceramic tube. The rate of outgassing of this colloid is 3.57×10^-12 Torr L s⁻¹ cm^-2 after baking. The ceramic tube was connected to a stainless-steel flange with the aid of a glass powder colloid and TIG welding. This ceramic test chamber will be installed in the experimental system to analyze the residual gas.

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WEPME055

Residual Gas in the 14 m-long Aluminium Vacuum System of the Storage Ring of Taiwan Photon Source: toward Ultra-high Vacuum

2396

T.Y. Lee, C.K. Chan, C.H. Chang, C.-C. Chang, S.W. Chang, Y.P. Chang, B.Y. Chen, J.-R. Chen, Z.W. Chen, C.M. Cheng, Y.T. Cheng, G.-Y. Hsiung, S-N. Hsu, H.P. Hsueh, C.S. Huang, Y.T. Huang, L.H. Wu, Y.C. Yang
NSRRC, Hsinchu, Taiwan

In the Taiwan Photon Source project, the storage ring includes 24 sectors (each of length 14 m) of an aluminium vacuum chamber system. The design, manufacture, cleaning, welding and assembly of the vacuum components were undertaken by the NSRRC vacuum group. The ultimate objective is to attain a leak-tight, ultra-high vacuum and a vacuum system with a small rate of outgassing. In this work, we used a residual-gas analyzer (RGA) to analyze the variation of residual gas during proceeding toward ultra-high vacuum. This process, which led the pressure down to ~10^-11 torr, includes baking, operation of ion pumps, degassing of hot cathode gauges and activation of NEG pumps. When a sufficiently small low pressure is attained, the ion pumps are turned off to test the building up of pressure. The outgassing property and the variation of the residual gas of the aluminium chamber and the ion pumps can be measured.

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WEPME056

Further Optimisation of NEG Coatings for Accelerator Beam Chamber

2399

O.B. Malyshev, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The non-evaporable getter (NEG) coating, invented at CERN in 90s, is used nowadays in many accelerators around the world. The main advantages of using NEG coatings are evenly distributed pumping speed, low thermal outgassing rates and low photon and electron stimulated gas desorption. The only downside of the NEG is its selective pumping: it pumps H2, CO, CO2 and some other gas species, but does not pump noble gases and hydrocarbons. However, in the accelerators where NEG coating could be beneficial, there is synchrotron radiation and photoelectrons that bombard vacuum chamber walls, it was found in our study that hydrocarbons can be pumped by NEG coating under electron and, most likely, photon bombardment. The detail and the results of this study are reported in this paper.

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WEPME057

The Secondary Electron Yield from Transition Metals

2403

S. Wang, M.D. Cropper
Loughborough University, Loughborough, Leicestershire, United Kingdom
O.B. Malyshev, E.A. Seddon, R. Valizadeh, S. Wang
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Non-evaporable getter thin films, which are currently being used in the ultra-high vacuum system of the Large Hadron Collider, normally consist of Ti, Zr and V, deposited by physical vapour deposition. In this study, the secondary electron yield (SEY) of bulk Ti, Zr, V and Hf have been investigated as a function of electron conditioning. The maximum SEYs of as-received Ti, Zr, V and Hf, are respectively 1.96, 2.34, 1.72 and 2.32, these reduce to 1.14, 1.13, 1.44 and 1.18 after electron conditioning. Surface chemical composition was studied by X-ray photoelectron spectroscopy which revealed that surface conditioning by electron bombardment promotes the growth of a thin carbon layer on the surface and consequently reduces the SEY of the surface as a function of electron dose. Heating a vanadium sample to 250°C resulted in diffusion of oxygen into the bulk and induced formation of metal carbide at the surface. However, the SEY stays the same even after heat-induced surface chemistry modification. Prolonged electron conditioning increases the surface oxygen but the surface is still predominantly covered with a thin graphitic layer and hence the SEY stays approximately constant.

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WEPME059

Conceptual Design of a Storage Ring Vacuum System Compatible with Implementation of a Seven Bend Achromat Lattice at the APS

2409

B.K. Stillwell, B. Brajuskovic, H. Cease, D.L. Fallin, J. R. Noonan, M.M. O'Neill
ANL, Argonne, Ilinois, USA

A conceptual design is presented for a storage ring vacuum system at the Advanced Photon Source (APS) which is compatible with a multi-bend achromat (MBA) lattice under development for the APS Upgrade (APS-U) project [1]. Together, the interface with the magnets, required quantity and stability of beam position monitors, synchrotron radiation loading, and beam physics requirements place a demanding set of constraints on the vacuum system design. However, the requirements can be satisfied with a hybrid system which combines conventional extruded aluminum chambers incorporating “antechambers” with a variety of simpler tubular chambers made variously of copper-plated stainless steel, NEG-coated copper, and bare aluminum. This hybrid system has advantages over an all NEG-coated copper system with regard to overall project risk, required installation time, and maintainability.

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WEPRI043

Implementation of Carbon Thin Film Coatings in the Super Proton Synchrotron (SPS) for Electron Cloud Mitigation

2574

P. Costa Pinto, T.C. Basso, A. Bellunato, P. Edwards, M. Mensi, A. Sublet, M. Taborelli
CERN, Geneva, Switzerland

Low Secondary Electron Yield (SEY) carbon thin films get rid of electron multipacting in accelerator beam pipes. Two magnetic cells of the SPS were coated with such material and installed. In total more than forty vacuum vessels and magnet interconnections were treated. The feasibility of the coating process was validated. The performance of the carbon thin film will be tested with LHC nominal beams after the end of the long shutdown 1. Particular attention will be drawn to the long term behaviour. This paper presents the sputtering techniques used to coat the different components; their characterization (SEY measurements on coupons, RF multipacting tests and pump down curves); and the technology to etch the carbon film in case of a faulty coating. The strategy to coat the entire SPS will also be exposed.

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