<?xml version="1.0" encoding="UTF-8"?> <rss version="2.0" xmlns:media="http://search.yahoo.com/mrss/" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:opensearch="http://a9.com/-/spec/opensearch/1.1/"> <channel> <title>CERN Document Server</title> <link>https://cds.cern.ch</link> <description>CERN Document Server latest documents</description> <language>en</language> <pubDate>Thu, 28 Nov 2024 16:49:09 GMT</pubDate> <category></category> <generator>Invenio 1.1.3.1106-62468</generator> <ttl>360</ttl> <atom:link rel="self" href="/rss?f=author&amp;ln=de&amp;p=Namora%2C+V" /> <opensearch:totalResults>15</opensearch:totalResults> <opensearch:startIndex>1</opensearch:startIndex> <opensearch:itemsPerPage>25</opensearch:itemsPerPage> <image> <url>https://cds.cern.ch/img/site_logo_rss.png</url> <title>CERN Document Server</title> <link>https://cds.cern.ch</link> </image> <atom:link rel="search" href="https://cds.cern.ch/opensearchdescription" type="application/opensearchdescription+xml" title="Content Search" /> <textInput> <title>Search </title> <description>Search this site:</description> <name>p</name> <link>https://cds.cern.ch/search</link> </textInput> <item> <title>SPS injection kicker system: 2023 operational experience and upgrade proposals for high-luminosity LHC</title> <link>https://cds.cern.ch/record/2912933</link> <description>The SPS injection kicker system comprises twelve MKP-S (small aperture) modules and four MKP-L (large aperture) modules. An upgraded MKP-L magnet was installed in the SPS, during December 2022, in view of the higher beam intensity needed in the future for High-Luminosity-LHC. The upgrades have significantly reduced the beam coupling impedance and consequent beam induced heating. The improved performance is due to a new beam screen, consisting of silver fingers painted on an alumina chamber, inserted in each magnet’s aperture. Additionally, a surface coating on the chamber's inner surface reduces its secondary electron yield and hence dynamic vacuum activity. The effectiveness of these upgrades was demonstrated during the 2023 operation. This paper provides an in-depth exploration of the initial year of operational experience with the upgraded MKP-L, giving a comparative analysis of dynamic vacuum and beam induced heating with the MKP-S modules. An alternative approach for upgrading the MKP-S modules, to reduce their temperature, is also proposed.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Favia, Giorgia</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Zannini, Carlo</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Standen, Dylan</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Velotti, Francesco</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ducimetière, Laurent</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Feliciano, Luis</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Barnes, Michael</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Diaz Zumel, Miguel</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Trubacova, Pavlina</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Kramer, Thomas</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Stadlbauer, Tobias</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Gomes Namora, Vasco</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Bartmann, Wolfgang</dc:creator> <pubDate>Wed, 09 Oct 2024 13:10:21 GMT</pubDate> <guid>https://cds.cern.ch/record/2912933</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/2912933/files/document.pdf"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">['']</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/"/> </item> <item> <title>Initial operational experience of an LHC injection kicker magnet upgraded for HL-LHC</title> <link>https://cds.cern.ch/record/2912916</link> <description>The intensity of the HL-LHC beam will be twice that of LHC. Hence, an upgrade of the LHC injection kickers (MKIs) is necessary for HL-LHC to avoid excessive beam induced heating of the MKIs. In addition, any newly installed MKI magnet would limit HL-LHC operation for a few hundred hours due to dynamic vacuum activity. Extensive studies have been carried out to identify solutions to address these problems and they have been implemented in an upgraded LHC injection kicker magnet (MKI Cool): the MKI Cool was installed in the LHC during the 2022-23 Year End Technical Stop. Magnet heating has been reduced by redistributing a significant portion of the beam induced power deposition from the ferrite yoke to a ferrite loaded RF Damper, which is not at pulsed high voltage, and by water cooling of the damper. Furthermore, a surface coating, to mitigate dynamic vacuum activity, has been applied. This paper discusses the upgrades, presents results from the initial operational experience, and compares the predicted and ‘measured’ beam induced power deposition.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Barnes, Michael</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Diaz Zumel, Miguel</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Bracco, Chiara</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Standen, Dylan</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Favia, Giorgia</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ducimetière, Laurent</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Trubacova, Pavlina</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Kramer, Thomas</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Stadlbauer, Tobias</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Gomes Namora, Vasco</dc:creator> <pubDate>Wed, 09 Oct 2024 13:10:04 GMT</pubDate> <guid>https://cds.cern.ch/record/2912916</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/2912916/files/document.pdf"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">['']</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/"/> </item> <item> <title>Operational experience of a low beam coupling impedance injection kicker magnet for the CERN SPS ring</title> <link>https://cds.cern.ch/record/2886323</link> <description>The CERN SPS injection kicker magnets (MKP) were developed in the 1970's, before beam power deposition was considered an issue. There are two types of these magnets in the SPS: MKP-S (small aperture) and MKP-L (large aperture) versions. The MKP-L magnets are very lossy from a beam impedance perspective: this would be an issue during SPS operation with the higher intensity beams needed in the future for HL-LHC. Hence, a beam screen has been developed, which is inserted in the aperture of each MKP-L module. The screen consists of silver fingers applied to alumina U-shaped chambers: the fingers have been optimized to achieve both adequately low beam induced power deposition and good high voltage (HV) behaviour. A surface coating, with a low secondary electron yield, is applied to the inner surface of the alumina chambers to reduce dynamic vacuum. The low-impedance MKP-L has been extensively HV tested in the lab before installation in the SPS. This paper briefly presents the design and focuses on the operational experience in the SPS, including heating and vacuum.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Barnes, M J</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Bartmann, W</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Díaz, M</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ducimetière, L</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Favia, G</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Feliciano, L</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Kramer, T</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Namora, V</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Standen, D</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Stadlbauer, T</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Trubacova, P</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Velotti, F</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Zannini, C</dc:creator> <pubDate>Fri, 12 Jan 2024 07:51:05 GMT</pubDate> <guid>https://cds.cern.ch/record/2886323</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/2886323/files/document.pdf"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">['']</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/"/> </item> <item> <title>Mitigation of High Voltage Breakdown of the Beam Screen of a CERN SPS Injection Kicker Magnet</title> <link>https://cds.cern.ch/record/2845881</link> <description>The SPS injection kicker magnets (MKP) were developed in the 1970’s, before beam induced power deposition was considered an issue. These magnets are very lossy from a beam impedance perspective: this is expected to be an issue during SPS operation with the higher intensity beams needed for HL-LHC. A design, with serigraphy applied to an alumina carrier, has been developed to significantly reduce the broadband beam coupling impedance and hence mitigate the heating issues. During high voltage pulse testing there were electrical discharges associated with the serigraphy. Detailed mathematical models have been developed to aid in understanding the transiently induced voltages and to reduce the magnitude and duration of electric field. In this paper, we discuss the solutions implemented to mitigate the electrical discharges while maintaining an adequately low beam-coupling impedance. In addition, the results of high voltage tests are reported. The alumina substrate has a high secondary electron yield and thus electron-cloud could be an issue, with SPS beam, if mitigating measures were not taken: this paper also discusses the measures implemented.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Barnes, Michael</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Bartmann, Wolfgang</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Díaz Zumel, Miguel</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ducimetière, Laurent</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Feliciano, Luis</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Kramer, Thomas</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Namora, Vasco</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Stadlbauer, Tobias</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Standen, Dylan</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Trubacova, Pavlina</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Velotti, Francesco</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Zannini, Carlo</dc:creator> <pubDate>Wed, 11 Jan 2023 05:09:43 GMT</pubDate> <guid>https://cds.cern.ch/record/2845881</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/2845881/files/document.pdf"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">['']</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/"/> </item> <item> <title>SPS Beam Dump System (SBDS) Commissioning After Relocation and Upgrade</title> <link>https://cds.cern.ch/record/2845740</link> <description>In order to overcome several machine limitations, the SBDS has been relocated from LSS1 (Long Straight Section 1) to LSS5 during LS2 (Long Shutdown 2) with an important upgrade of the extraction kicker installation. An additional vertical deflection kicker magnet (MKDV) was produced and installed while the high voltage (HV) pulse generators have been upgraded by changing gas-discharge switches (thyratrons and ignitrons) to semiconductor stacks operating in oil. Furthermore the horizontal sweep generators have been upgraded to allow for a lower kick strengths. The controls, previously consolidated during LS1, went through an additional light consolidation phase with among others the upgrade of the trigger &amp;amp; retrigger distribution system and the installation of a new fast-interlocks detection system. This paper describes the commissioning without and with beam and elaborates on the measured improvements and encountered problems with corrective mitigations.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Van Trappen, Pieter</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Carlier, Etienne</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ducimetière, Laurent</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Namora, Vasco</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Senaj, Viliam</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Velotti, Francesco</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Voumard, Nicolas</dc:creator> <pubDate>Wed, 11 Jan 2023 05:07:58 GMT</pubDate> <guid>https://cds.cern.ch/record/2845740</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/2845740/files/document.pdf"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">['']</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/"/> </item> <item> <title>Studies for Mitigating Flashover of CERN-LHC Dilution Kicker Magnets</title> <link>https://cds.cern.ch/record/2810000</link> <description>The LHC beam dump system is used for extracting beam from the LHC and, as such, is a safety critical system whose proper functionality must be assured. Dilution kicker magnets (MKBs) sweep the extracted beam over the cross-sectional area of a dump block as the energy density would otherwise be too high and damage the block. In 2018, a high voltage flashover occurred in a vertical MKB (MKBV) vacuum tank, during a beam dump, which resulted in non-ideal sweep of the beam over the block. The location of the flashover could not be identified during a subsequent inspection of the magnet. Hence, electrical field simulations have been carried out to identify potentially critical regions, to determine the most probable region of the flashover. One potentially critical region is a rectangular beam pipe (RBP) between the end of the tank and the MKBV magnet, whose purpose is to reduce plasma propagation to the adjacent tank in the event of a flashover. Mitigating measures were studied and are reported in this paper.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Loebner, Alina M</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Barnes, Michael J</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Bartmann, Wolfgang</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Bracco, Chiara</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ducimetière, Laurent</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Namora, Vasco</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Senaj, Viliam</dc:creator> <pubDate>Sat, 21 May 2022 04:07:13 GMT</pubDate> <guid>https://cds.cern.ch/record/2810000</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/2810000/files/document.pdf"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">['']</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/"/> </item> <item> <title>Machine protection aspects of high-voltage flashovers of the LHC beam dump dilution kickers</title> <link>https://cds.cern.ch/record/2693721</link> <description>The LHC Beam Dump System is required to safely dispose of the energy of the stored beam. In order to reduce the energy density deposited in the beam dump, a dedicated dilution system is installed. On July 14, 2018, during a regular beam dump at 6.5 TeV beam energy, a high-voltage flashover of two vertical dilution kickers was observed, leading to a voltage breakdown and reduced dilution in the vertical plane. It was the first incident of this type since the start of LHC beam operation. In this paper, the flashover event is described and the implications analysed. Circuit simulations of the current in the magnet coil as well as simulations of the resulting beam sweep pattern are presented and compared with the measurements. The criticality of the event is assessed and implications for future failure scenarios are discussed.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Wiesner, Christoph</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Bartmann, Wolfgang</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Bracco, Chiara</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Calviani, Marco</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Carlier, Etienne</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ducimetière, Laurent</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Frankl, Matthias</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fraser, Matthew</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Gilardoni, Simone</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Goddard, Brennan</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Namora, Vasco</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Kramer, Thomas</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Lechner, Anton</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Magnin, Nicolas</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Meddahi, Malika</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Perillo-Marcone, Antonio</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Polzin, Tobias</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Richtmann, Lea</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Rizzoglio, Valeria</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Senaj, Viliam</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ferreira Somoza, Jose</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Wollmann, Daniel</dc:creator> <pubDate>Wed, 16 Oct 2019 05:35:59 GMT</pubDate> <guid>https://cds.cern.ch/record/2693721</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/2693721/files/wepmp040.pdf"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">['']</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/"/> </item> <item> <title>Eradication of Mercury Ignitron from the 400 kA Magnetic Horn Pulse Generator for CERN Antiproton Decelerator</title> <link>https://cds.cern.ch/record/2672526</link> <description>The CERN Antiproton Decelerator (AD) produces low-energy antiprotons for studies of antimatter. A 26 GeV proton beam impacts the AD production target which produces secondary particles including antiprotons. A magnetic Horn (AD-Horn) in the AD target area is used to focus the diverging antiproton beam and increase the antiproton yield enormously. The horn is pulsed with a current of 400 kA, generated by capacitor discharge type generators equipped with ignitrons. These mercury-filled devices present a serious danger of environmental pollution in case of accident and safety constraints. An alternative has been developed using solid-state switches and diodes. Similar technology was already implemented at CERN for ignitron eradication in the SPS Horizontal beam dump in the early 2000s. A project was launched to design and set up a full-scale test-bench, to install and test a dedicated solid-state solution. Following the positive results obtained from the test-bench, the replacement of ignitrons by solid-state devices in the operational AD-Horn facility is currently under preparation. This paper describes the test-bench design and results obtained for this very high current pulser.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Namora, Vasco</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Calviani, Marco</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ducimetière, Laurent</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Faure, Patrick</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Fernandez, Luis</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Grawer, Gregor</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Senaj, Viliam</dc:creator> <pubDate>Thu, 25 Apr 2019 04:31:12 GMT</pubDate> <guid>https://cds.cern.ch/record/2672526</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/2672526/files/wepmf086.pdf"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">['']</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/"/> </item> <item> <title>Instabilities and beam induced heating in 2015</title> <link>https://cds.cern.ch/record/2294522</link> <description>Instabilities were observed during operation at injection, flat top and during the betatron squeeze. This resulted in high chromaticities and octupole currents in all stages of the machine cycle. A series of dedicated measurements at flat top and end of squeeze of the instability threshold was performed which can shine a light on expected performance in 2016. Beam induced rf heating will also be reported on, with emphasis placed on the performance of the MKI kicker and the effect of the bunch length.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Carver, L R</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Arduini, G</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Astapovych, D</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Barnes, M</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Barranco, J</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Biancacci, N</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Buffat, X</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Day, H</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Hofle, W</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Iadarola, G</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Kotzian, G</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Levens, T</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Li, K</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Métral, E</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Namora, V</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Persson, T</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Pieloni, T</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Rumolo, G</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Salvant, B</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Schenk, M</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Tambasco, C</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Tómas, R</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Valuch, D</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Vega Cid, L</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Wang, N</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Weterings, W</dc:creator> <pubDate>Tue, 28 Nov 2017 06:03:07 GMT</pubDate> <guid>https://cds.cern.ch/record/2294522</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/2294522/files/1637016_95-100.pdf"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">['']</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/"/> </item> <item> <title>Operational Experience of the Upgraded LHC Injection Kicker Magnets</title> <link>https://cds.cern.ch/record/2207462</link> <description>During Run 1 of the LHC the injection kicker magnets caused occasional operational delays due to beam induced heating with high bunch intensity and short bunch lengths. In addition, sometimes there were also sporadic issues with microscopic unidentified falling objects, vacuum activity and electrical flashover of the injection kickers. An extensive program of studies was launched and significant upgrades were carried out during long shutdown 1. These upgrades include a new design of a beam screen to both reduce the beam coupling impedance of the kicker magnet, and to significantly reduce the electric field associated with the screen conductors, hence decreasing the probability of electrical breakdown in this region. In addition new cleaning procedures were implemented and equipment adjacent to the injection kickers and various vacuum components were modified. This paper presents operational experience of the injection kicker magnets during Run 2 of the LHC and assesses the effectiveness of the various upgrades.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Barnes, Michael</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Adraktas, Antonios</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Bregliozzi, Giuseppe</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Calatroni, Sergio</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Day, Hugo</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ducimetière, Laurent</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Goddard, Brennan</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Gomes Namora, Vasco</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Mertens, Volker</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Salvant, Benoit</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Uythoven, Jan</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Vega Cid, Lorena</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Weterings, Wim</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Yin Vallgren, Christina</dc:creator> <pubDate>Fri, 12 Aug 2016 04:32:41 GMT</pubDate> <guid>https://cds.cern.ch/record/2207462</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/2207462/files/thpmw033.pdf"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">['']</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/"/> </item> <item> <title>High Voltage Performance of the Beam Screen of the LHC Injection Kicker Magnets</title> <link>https://cds.cern.ch/record/1966020</link> <description>The LHC injection kicker magnets include beam screens to shield the ferrite yokes against wakefields resulting from the high intensity beam. The screening is provided by conductors lodged in the inner wall of a ceramic support tube. The design of the beam screen has been upgraded to overcome limitations and permit LHC operation with increasingly higher bunch intensity and short bunch lengths: the new design also significantly reduces the electric field associated with the screen conductors, decreasing the probability of electrical breakdown. The high voltage conditioning process for the upgraded kicker magnets is presented and discussed. In addition a test setup has been utilized to study flashover, on the inner wall of the ceramic tube, as a function of both applied voltage and vacuum pressure: results from the test setup are presented.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Barnes, MJ</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Adraktas, P</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Bregliozzi, G</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Calatroni, S</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Costa Pinto, P</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Day, H</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ducimetière, L</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Kramer, T</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Namora, V</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Mertens, V</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Taborelli, M</dc:creator> <pubDate>Thu, 30 Oct 2014 15:50:01 GMT</pubDate> <dc:date xmlns:dc="http://purl.org/dc/elements/1.1/">30 Oct 2014</dc:date> <dc:source xmlns:dc="http://purl.org/dc/elements/1.1/">CERN-ACC-2014-0242</dc:source> <guid>https://cds.cern.ch/record/1966020</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/1966020/files/CERN-ACC-2014-0242.pdf"/> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/1966020/files/CERN-ACC-2014-0242.pdf?subformat=pdfa"/> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://accelconf.web.cern.ch/IPAC2014/papers/mopme074.pdf"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">2014</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/">0242</dc:hasVersion> </item> <item> <title>Cooling of the LHC Injection Kicker Magnet Ferrite Yoke: Measurements and Future Proposals</title> <link>https://cds.cern.ch/record/1966019</link> <description>LHC operation with high intensity beam, stable for many hours, resulted in significant heating of the ferrite yoke of the LHC Injection Kicker Magnets. For one kicker magnet the ferrite yoke approached its Curie temperature. As a result of a long thermal time-constant the yoke can require several hours to cool sufficiently to allow re-injection of beam, thus limiting the running efficiency of the LHC. The beam screen, which screens the ferrite yoke from wakefields, has been upgraded to limit ferrite heating. In addition it is important to improve the cooling of the ferrite yoke: one method is to increase the internal emissivity of the cylindrical vacuum tank, in which the kicker magnet is installed. This paper describes a method developed for measuring the emissivity of the inside of the tanks, which has been benchmarked against measurements of the ferrite yoke temperature during heat treatment in an oven and transient thermal simulations. Conclusions are drawn regarding an ion bombardment technique evaluated for improving emissivity without degrading vacuum properties. In addition initial concepts for improved cooling are presented.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Sobiech, Z</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Barnes, MJ</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Bouleghlimat, S</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ducimetière, L</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Garlaschè, M</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Kramer, T</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Namora, V</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Noulibos, R</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Sillanoli, Y</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Weterings, W</dc:creator> <pubDate>Thu, 30 Oct 2014 15:39:55 GMT</pubDate> <dc:date xmlns:dc="http://purl.org/dc/elements/1.1/">30 Oct 2014</dc:date> <dc:source xmlns:dc="http://purl.org/dc/elements/1.1/">CERN-ACC-2014-0241</dc:source> <guid>https://cds.cern.ch/record/1966019</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/1966019/files/CERN-ACC-2014-0241.pdf"/> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/1966019/files/CERN-ACC-2014-0241.pdf?subformat=pdfa"/> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://accelconf.web.cern.ch/IPAC2014/papers/mopme075.pdf"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">2014</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/">0241</dc:hasVersion> </item> <item> <title>Upgrade of the LHC Injection Kicker Magnets</title> <link>https://cds.cern.ch/record/1574598</link> <description>Two LHC injection kicker systems, each comprising 4 magnets per ring, produce a kick of 1.3 T·m with a rise-time of less than 900 ns and a flattop ripple of less than ±0.5%. A beam screen is placed in the aperture of each magnet, to provide a path for the image current of the LHC beam and screen the ferrite yoke against wake fields. The screen consists of a ceramic tube with conductors in the inner wall. The initially implemented beam screen ensured a low rate of electrical breakdowns and an adequately low beam coupling impedance. Operation with increasingly higher intensity beams, stable for many hours at a time, has resulted in substantial heating of the ferrite yoke, sometimes requiring cool-down over several hours before the LHC can be refilled. During the long shutdown in 2013/2014 all eight kicker magnets will be upgraded with an improved beam screen and an increased emissivity of the vacuum tank. In addition equipment adjacent to the injection kickers and various vacuum components will be modified to reduce the vacuum pressure near to the kickers during high-intensity operation. This paper discusses the upgrades.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Adraktas, P</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Baglin, V</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Bregliozzi, G</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Caspers, F</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Calatroni, S</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Day, H</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ducimetière, L</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Garlaschè, M</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Gomes Namora, V</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Jimenez, J M</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Magnin, N</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Mertens, V</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Métral, E</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Salvant, B</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Taborelli, M</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Uythoven, J</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Weterings, W</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Barnes, M J</dc:creator> <pubDate>Wed, 14 Aug 2013 09:33:23 GMT</pubDate> <dc:date xmlns:dc="http://purl.org/dc/elements/1.1/">31 Jul 2013</dc:date> <dc:source xmlns:dc="http://purl.org/dc/elements/1.1/">CERN-ACC-2013-0077</dc:source> <guid>https://cds.cern.ch/record/1574598</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/1574598/files/CERN-ACC-2013-0077.pdf"/> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/1574598/files/CERN-ACC-2013-0077.pdf?subformat=pdfa"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">2013</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/">0077</dc:hasVersion> </item> <item> <title>Reduction of Surface Flashover of the Beam Screen of the LHC Injection Kickers</title> <link>https://cds.cern.ch/record/1574591</link> <description>The LHC injection kicker magnets include beam screens to shield the ferrite yokes against wake fields resulting from the high intensity beam. The screening is provided by conductors lodged in the inner wall of a ceramic support tube. LHC operation with increasingly higher bunch intensity and short bunch lengths, requires improved ferrite screening. This will be implemented by additional conductors; however these must not compromise the good high-voltage behaviour of the kicker magnets. Extensive studies have been carried out to better satisfy the often conflicting requirements for low beam coupling impedance, fast magnetic field rise-time, ultra-high vacuum and good high voltage behaviour. A new design is proposed which significantly reduces the electric field associated with the screen conductors. Results of high voltage tests are also presented.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Adraktas, P</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Calatroni, S</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Caspers, F</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ducimetière, L</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Gomes Namora, V</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Mertens, V</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Noulibos, R</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Taborelli, M</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Teissandier, B</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Uythoven, J</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Weterings, W</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Barnes, M J</dc:creator> <pubDate>Wed, 14 Aug 2013 09:08:42 GMT</pubDate> <dc:date xmlns:dc="http://purl.org/dc/elements/1.1/">31 Jul 2013</dc:date> <dc:source xmlns:dc="http://purl.org/dc/elements/1.1/">CERN-ACC-2013-0075</dc:source> <guid>https://cds.cern.ch/record/1574591</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/1574591/files/CERN-ACC-2013-0075.pdf"/> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/1574591/files/CERN-ACC-2013-0075.pdf?subformat=pdfa"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">2013</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/">0075</dc:hasVersion> </item> <item> <title>Beam Induced Ferrite Heating of the LHC Injection Kickers and Proposals for Improved Cooling</title> <link>https://cds.cern.ch/record/1574588</link> <description>The two LHC injection kicker systems produce an integrated field strength of 1.3 T·m with a flattop duration variable up to 7860 ns, and rise and fall times of less than 900 ns and 3000 ns, respectively. A beam screen is placed in the aperture of each magnet, which consists of a ceramic tube with conductors in the inner wall. The conductors provide a path for the beam image current and screen the ferrite yoke against wakefields. Recent LHC operation, with high intensity beam stable for many hours, resulted in significant heating of both the ferrite yoke and beam impedance reduction ferrites. For one kicker magnet the ferrite yoke approached its Curie temperature. As a result of a long thermal time-constant the ferrite yoke can require several hours to cool sufficiently to allow re-injection of beam, thus limiting the running efficiency of the LHC. Thermal measurement data has been analysed, a thermal model developed and emissivity measurements carried out. Various measures to improve the ferrite cooling have been simulated, including an improved emissivity of the vacuum tank and active cooling on the outside of the tank.</description> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Caspers, F</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Calatroni, S</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Day, H</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Ducimetière, L</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Garlaschè, M</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Gomes Namora, V</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Mertens, V</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Sobiech, Z</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Taborelli, M</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Uythoven, J</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Weterings, W</dc:creator> <dc:creator xmlns:dc="http://purl.org/dc/elements/1.1/">Barnes, M J</dc:creator> <pubDate>Wed, 14 Aug 2013 08:59:59 GMT</pubDate> <dc:date xmlns:dc="http://purl.org/dc/elements/1.1/">31 Jul 2013</dc:date> <dc:source xmlns:dc="http://purl.org/dc/elements/1.1/">CERN-ACC-2013-0073</dc:source> <guid>https://cds.cern.ch/record/1574588</guid> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/1574588/files/CERN-ACC-2013-0073.pdf"/> <media:content xmlns:media="http://search.yahoo.com/mrss/" url="https://cds.cern.ch/record/1574588/files/CERN-ACC-2013-0073.pdf?subformat=pdfa"/> <dc:title xmlns:dc="http://purl.org/dc/elements/1.1/" xml:lang="fr"/> <dc:hasPart xmlns:dc="http://purl.org/dc/elements/1.1/">2013</dc:hasPart> <dc:hasVersion xmlns:dc="http://purl.org/dc/elements/1.1/">0073</dc:hasVersion> </item> </channel> </rss>