| Paper | Title | Page |
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| MOPMF062 | Upgrade of the Dilution System for HL-LHC | 261 |
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| The LHC Beam Dump System is one of the most critical systems for reliable and safe operation of the LHC. A dedicated dilution system is required to sweep the beam over the front face of the graphite dump core in order to reduce the deposited energy density. The High Luminosity Large Hadron Collider (HL-LHC) project foresees to increase the total beam intensity in the ring by nearly a factor of two, resulting in a correspondingly higher energy deposition in the dump core. In this paper, the beam sweep pattern and energy deposition for the case of normal dilution as well as for the relevant failure cases are presented. The implications as well as possible mitigations and upgrade measures for the dilution system, such as decreasing the pulse-generator voltage, adding two additional kickers, and implementing a retrigger system, are discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF062 | |
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| MOPMF063 | Asynchronous Beam Dump Tests at LHC | 265 |
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| The detailed understanding of the beam-loss pattern in case of an asynchronous beam dump is essential for the safe operation of the future High Luminosity LHC (HL-LHC) with nearly twice the nominal LHC beam intensity, leading to correspondingly higher energy deposition on the protection elements. An asynchronous beam dump is provoked when the rise time of the extraction kickers is not synchronized to the 3 us long particle-free abort gap. Thus, particles that are not absorbed by dedicated protection elements can be lost on the machine aperture. Since asynchronous beam dumps are among the most critical failure cases of the LHC, experimental tests at low intensity are performed routinely. This paper reviews recent asynchronous beam dump tests performed in the LHC. It describes the test conditions, discusses the beam-loss behaviour and presents simulation and measurement results. In particular, it examines a test event from May 2016, which led to the quench of four superconducting magnets in the extraction region and which was studied by a dedicated beam experiment in December 2017. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF063 | |
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| TUPAF028 | Energy Deposition Studies and Analysis of the Quench Behavior in the Case of Asynchronous Dumps During 6.5 TeV LHC Proton Beam Operation | 736 |
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| The CERN LHC beam dumping system comprises a series of septa and fast-pulsed kicker magnets for extracting the stored proton beams to the external beam dumps. Different absorbers in the extraction region protect superconducting magnets and other machine elements in case of abnormal beam aborts, where bunches are swept across the machine aperture. During Run 2 of the LHC, controlled beam loss experiments were carried out at 6.5 TeV probing the particle leakage from protection devices under realistic operation conditions. This paper presents particle shower simulations analyzing the energy deposition in superconducting coils and assessing if the observed magnet quenches are compatible with the presently known quench limits. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF028 | |
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| WEPMF071 | Dynamic Testing and Characterization of Advanced Materials in a New Experiment at CERN HiRadMat Facility | 2534 |
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Funding: This work has received funding from the European Union's Horizon 2020 Research and Innovation programme under Grant Agreement No 730871. An innovative and comprehensive experiment (named "Multimat") was successfully carried out at CERN HiRadMat facility on 18 different materials relevant for Collimators and Beam Intercepting Devices. Material samples, tested under high intensity proton pulses of 440 GeV/c, exceeding the energy density expected in HL-LHC, ranged from very light carbon foams to tungsten heavy alloys, including novel composites as graphite/carbides and metal/diamond without and with thin-film coatings. Experimental data were acquired relying on extensive integrated instrumentation (strain gauges, temperature sensors, radiation-hard camera) and on laser Doppler vibrometer. This allows investigating relatively unexplored and fundamental phenomena as dynamic strength, internal energy dispersion, nonlinearities due to inelasticity and inhomogeneity, strength and delamination of coatings and surfaces. By benchmarking sophisticated numerical simulations against these results, it is possible to establish or update material constitutive models, which are of paramount importance for the design of devices exposed to interaction with particle beams in high energy accelerators such as the HL-LHC or FCC-hh. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF071 | |
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