101,923 research outputs found
Influence of Atmospheric Humidity and Grain Size on the Friction and Wear of High Nitrogen Austenitic Stainless Steel
No full textFriction and wear behaviour of AISI 304 austenitic stainless steel: influence of atmospheric humidity, load range and grain size
No full textAmorphous Carbon Coatings at Cryogenic Temperatures with LHC Type Beams: First Results with the COLDEX Experiment
No full textExtrapolations of electron cloud data from the Large Hadron Collider (LHC) Run 1 to the High Luminosity upgrade (HL-LHC) beam parameters predict an intolerable increase of heat load on the beam screens of the inner triplets. Amorphous carbon (a-C) coating of the beam screen surface is proposed to reduce electron cloud production, thereby minimising its dissipated power. To validate this solution, the COLDEX experiment has been re-commissioned. Such equipment mimics the performance of the LHC cold bore and beam screen cryogenic vacuum system in presence of LHC beams in the Super Proton Synchrotron (SPS). The main objective of the study is the performance evaluation of a-C coatings while operating the beam screen in the 10 to 60 K temperature range and cold bore below 3 K. This paper reviews the status of COLDEX and the results obtained during its first experimental runs
Measurement of NEG Coating Performance Variation in the LHC after the First Long Shutdown
No full textDuring the Long Shutdown 1 (LS1) of the Large Hadron Collider, 90% of the Non-Evaporable Getter (NEG) coated beam pipes in the Long Straight Sections (LSS) were vented to undertake the planned upgrade and consolidation programmes. After each intervention, an additional bake-out and NEG activation were performed to reach the vacuum requirements. An analysis of the coating performance variation after the additional activation cycle has been carried out by using ultimate pressure and pressure build-up measurements. In addition, laboratory measurements have been carried out to mimic the LHC coated beam pipe behaviour. The experimental data have been compared with calculation obtained by Molflow+
Fluorinated amorphous carbon thin films: Analysis of the role of the plasma excitation mode on the structural and mechanical properties
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Microtribological investigations on fluorocarbon thin films deposited in continuous and modulated C2F4 RF glow discharges
No full textEffect of load range, relative humidity and grain size on the microfriction behaviour of AISI 304 austenitic stainless steel
No full textUltra-high vacuum characterization of molybdenum-carbide graphite for HL-LHC collimators
No full textIn view of the High-Luminosity upgrade of the Large Hadron Collider (LHC) collimation system, a family of novel molybdenum-carbide graphite (MoGr) composites was developed to meet the challenging requirements of HL-LHC beam-halo collimation, in particular the electrical conductivity and thermo-mechanical performances. The Ultra-High Vacuum (UHV) behaviour of this material was extensively characterized to assess its compatibility with the accelerator’s specifications. The results presented in this paper correlate the outgassing behaviour with the microscopic features of MoGr compared to other graphite-based materials. Residual gas analysis (RGA) was exploited to optimize post-production treatments
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