333 research outputs found
Beam-Induced Damage Mechanisms and their Calculation
The rapid interaction of highly energetic particle beams with matter induces
dynamic responses in the impacted component. If the beam pulse is sufficiently
intense, extreme conditions can be reached, such as very high pressures,
changes of material density, phase transitions, intense stress waves, material
fragmentation and explosions. Even at lower intensities and longer time-scales,
significant effects may be induced, such as vibrations, large oscillations, and
permanent deformation of the impacted components. These lectures provide an
introduction to the mechanisms that govern the thermomechanical phenomena
induced by the interaction between particle beams and solids and to the
analytical and numerical methods that are available for assessing the response
of impacted components. An overview of the design principles of such devices is
also provided, along with descriptions of material selection guidelines and the
experimental tests that are required to validate materials and components
exposed to interactions with energetic particle beams.Comment: 69 pages, contribution to the 2014 Joint International Accelerator
School: Beam Loss and Accelerator Protection, Newport Beach, CA, USA , 5-14
Nov 201
ANALYSIS AND DESIGN OF THE ACTUATION SYSTEM FOR THE LHC COLLIMATORS (PHASE I)
In order to cope with the highly destructive particle beam of the LHC, the cleaning and collimation system must fulfill very severe requirements. The actuation system of the LHC Collimators is a key element to meet the specifications, particularly in terms of precision and reliability. Each collimator jaw has to be moved with a very high accuracy to place the active surface at the required position with respect to the proton beam; at the same time the system must be adjustable and flexible to adapt to the uncertainties and variations in the beam tuning. In this note the general design of the actuation system for the various collimator designs is presented and particular emphasis is given to the analysis of the torque which the stepper motors must provide to move the jaws in and back and to the dynamical behaviour of the system in the event of malfunctioning when auto-retraction of the jaws is required. In the appendix, details are given on the estimated performances of the actuation system for different collimator types and orientations
On the application of piezolaminated composites to diaphragm micropumps
This paper deals with the numerical simulation of piezolaminated microplates adopted as actuators in micropumps. The performances of piezoelectric actuation is critically assessed by means of comparisons with devices based on the electrostatic force
Numerical simulations of tungsten targets hit by LHC proton beam
The unprecedented energy intensities of modern hadron accelerators yield special
problems with the materials that are placed close to or into the high intensity beams. The
energy stored in a single beam of LHC particle accelerator is equivalent to about 80 kg of
TNT explosive, stored in a transverse beam area with a typical value of 0.2 mmĂ—0.2 mm. The
materials placed close to the beam are used at, or even beyond, their damage limits. However,
it is very difficult to predict structural efficiency and robustness accurately: beam-induced
damage for high energy and high intensity occurs in a regime where practical experience does
not exist. The interaction between high energy particle beams and metals induces a sudden
non uniform temperature increase. This provokes a dynamic response of the structure
entailing thermal stress waves and thermally induced vibrations or even the failure of the
component. This study is performed in order to estimate the damage on a tungsten component
due to the impact with a proton beam generated by LHC. The solved problems represent some
accidental cases consequent to an abnormal release of the beam: the energy delivered on the
components is calculated using the FLUKA code and then used as input in the numerical
simulations, that are carried out via the FEM code LS-DYNA
Summary of the CERN Workshop on Materials for Collimators and Beam Absorbers
The main focus of the workshop was on collimators and beam absorbers for (mainly) High Energy Hadron Accelerators, with the energy stored in the beams far above damage limit. The objective was to better understand the technological limits imposed by mechanisms related to beam impact on materials. The idea to organise this workshop came up during the High Intensity High Brightness Hadron Beams, ICFA-HB2006 in Japan [1]. The workshop was organised 3-5 September 2007 at CERN, with about 60 participants, including 20 from outside CERN. About 30 presentations were given [2]. The event was driven by the LHC challenge, with more than 360 MJoule stored in each proton beam. The entire beam or its fraction will interact with LHC collimators and beam absorbers, and with the LHC beam dump blocks. Collimators and beam absorbers are also of the interest for other labs and accelerators: - CERN: for the CNGS target, for SPS beam absorbers (extraction protection) and collimators for protecting the transfer line between SPS and LHC - GSI: SIS18 and SIS 100/200, Super-FRS target, HED experiments, Antiproton target, etc. - Fermilab: Tevatron and Main Injector collimation systems; neutrino production targets (MINOS, SNuMI, NOVA); antiproton production targets; pion production targets and beam absorbers for neutrino factories and muon colliders - ILC: positron production targets, beam absorbers and collimators for a beam delivery system
Measurements of heavy ion beam losses from collimation
The collimation efficiency for Pb ion beams in the LHC is predicted to be
lower than requirements. Nuclear fragmentation and electromagnetic dissociation
in the primary collimators create fragments with a wide range of Z/A ratios,
which are not intercepted by the secondary collimators but lost where the
dispersion has grown sufficiently large. In this article we present
measurements and simulations of loss patterns generated by a prototype LHC
collimator in the CERN SPS. Measurements were performed at two different
energies and angles of the collimator. We also compare with proton loss maps
and find a qualitative difference between Pb ions and protons, with the maximum
loss rate observed at different places in the ring. This behavior was predicted
by simulations and provides a valuable benchmark of our understanding of ion
beam losses caused by collimation.Comment: 12 pages, 20 figure
Mechanical robustness of HL-LHC collimator designs
Two new absorbing materials were developed as collimator inserts to fulfil the requirements of HL-LHC higher brightness beams: molybdenum-carbide graphite (MoGr) and copper-diamond (CuCD). These materials were tested under intense beam impacts at CERN HiRadMat facility in 2015, when full jaw prototypes were irradiated. Additional tests in HiRadMat were performed in 2017 on another series of material samples, including also improved grades of MoGr and CuCD, and different coating solutions. This paper summarizes the main results of the two experiments, with a main focus on the behaviour of the novel composite blocks, the metallic housing, as well as the cooling circuit. The experimental campaign confirmed the final choice for the materials and the design solutions for HL-LHC collimators, and constituted a unique chance of benchmarking numerical models. In particular, the tests validated the selection of MoGr for primary and secondary collimators, and CuCD as a valid solution for robust tertiary collimators
The "Multimat" experiment at CERN HiRadMat facility: advanced testing of novel materials and instrumentation for HL-LHC collimators
The increase of the stored beam energy in future particle accelerators, such as the HL-LHC and the FCC, calls for a radical upgrade in the design, materials and instrumentation of Beam Intercepting Devices (BID), such as collimators Following successful tests in 2015
that validated new composite materials and a novel jaw design conceived for the HL-LHC collimators, a new HiRadMat experiment, named “HRMT36-MultiMat”, is scheduled for autumn 2017. Its objective is to determine the behaviour under high intensity proton beams of a broad range of materials relevant for collimators and beam intercepting devices, thin-film coatings and advanced equipment. The test bench features 16 separate target stations, each hosting various specimens, allowing the exploration of complex phenomena such as dynamic strength, internal damping, nonlinearities due to anisotropic inelasticity and inhomogeneity, effects of energy deposition and radiation on coatings. This paper details the main technical solutions and engineering
calculations for the design of the test bench and of the specimens, the candidate target materials and the instrumentation system
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