Author: Wiesner, C.
Paper Title Page
MOPAB022 FailSim: A Numerical Toolbox for the Study of Fast Failures and Their Impact on Machine Protection at the CERN Large Hadron Collider 111
 
  • C. Hernalsteens, G. Sterbini, O.K. Tuormaa, C. Wiesner, D. Wollmann
    CERN, Geneva, Switzerland
  
  The High Lu­mi­nos­ity LHC (HL-LHC) fore­sees to reach a nom­i­nal, lev­elled lu­mi­nos­ity of 5·1034 cm-2 s−1 through a higher beam bright­ness and by using new equip­ment, such as larger aper­ture final fo­cus­ing quadru­pole mag­nets. The HL-LHC up­grade has crit­i­cal im­pacts on the ma­chine pro­tec­tion strat­egy, as the stored beam en­ergy reaches 700 MJ for each of the two beams. Some fail­ure modes of the novel ac­tive su­per­con­duct­ing mag­net pro­tec­tion sys­tem of the inner triplet mag­nets, namely the Cou­pling-Loss In­duced Quench (CLIQ) sys­tems, have been iden­ti­fied as crit­i­cal. This paper re­ports on Fail­Sim, a Python-lan­guage frame­work de­vel­oped to study the ma­chine pro­tec­tion im­pact of fail­ure cases and their pro­posed mit­i­ga­tion. It pro­vides seam­less in­te­gra­tion of the suc­ces­sive phases re­quired by the sim­u­la­tion stud­ies, i.e., ver­i­fy­ing the op­tics, prepar­ing and run­ning a MAD-X in­stance for mul­ti­ple par­ti­cle track­ing, pro­cess­ing and analysing the sim­u­la­tion re­sults and sum­maris­ing them with the rel­e­vant plots to pro­vide a solid es­ti­mate of the beam losses, their lo­ca­tion and time evo­lu­tion. The paper also pre­sents and dis­cusses the re­sult of its ap­pli­ca­tion on the spu­ri­ous dis­charge of a CLIQ unit.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB022  
About • paper received ※ 18 May 2021       paper accepted ※ 31 May 2021       issue date ※ 18 August 2021  
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MOPAB023 Experimental Test of a New Method to Verify Retraction Margins Between Dump Absorbers and Tertiary Collimators at the LHC 115
 
  • C. Wiesner, W. Bartmann, C. Bracco, R. Bruce, J. Molson, M. Schaumann, C. Staufenbiel, J.A. Uythoven, M. Valette, J. Wenninger, D. Wollmann, M. Zerlauth
    CERN, Meyrin, Switzerland
  
  The pro­tec­tion of the ter­tiary col­li­ma­tors (TCTs) and the LHC triplet aper­ture in case of a so-called asyn­chro­nous beam dump re­lies on the cor­rect re­trac­tion be­tween the TCTs and the dump re­gion ab­sorbers. A new method to val­i­date this re­trac­tion has been pro­posed, and a proof-of-prin­ci­ple ex­per­i­ment was per­formed at the LHC. The method uses a long orbit bump to mimic the change of the beam tra­jec­tory caused by an asyn­chro­nous fir­ing of the ex­trac­tion kick­ers. It can, thus, be per­formed with cir­cu­lat­ing beam. This paper re­ports on the per­formed beam mea­sure­ments, com­pares them with ex­pec­ta­tions and dis­cusses the po­ten­tial ben­e­fits of the new method for ma­chine pro­tec­tion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB023  
About • paper received ※ 19 May 2021       paper accepted ※ 25 August 2021       issue date ※ 24 August 2021  
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MOPAB024 Efficient Coupling of Hydrodynamic and Energy-Deposition Codes for Hydrodynamic-Tunnelling Studies on High-Energy Particle Accelerators 119
 
  • C. Wiesner, F. Carra, J. Kruse-Hansen, M. Masci, D. Wollmann
    CERN, Meyrin, Switzerland
  • Y. Nie
    KIT, Karlsruhe, Germany
  
  The ma­chine-pro­tec­tion eval­u­a­tion of high-en­ergy ac­cel­er­a­tors com­prises the study of be­yond-de­sign fail­ures, in­clud­ing the di­rect beam im­pact onto ma­chine el­e­ments. In case of a di­rect im­pact, the nom­i­nal beam of the Large Hadron Col­lider (LHC) would pen­e­trate more than 30 me­ters into a solid cop­per tar­get. The pen­e­tra­tion depth due to the time struc­ture of the par­ti­cle beam is, thus, sig­nif­i­cantly longer than pre­dicted from purely sta­tic en­ergy-de­po­si­tion sim­u­la­tions with 7 TeV pro­tons. This ef­fect, known as hy­dro­dy­namic tun­nelling, is caused by the beam-in­duced den­sity de­ple­tion of the ma­te­r­ial at the tar­get axis, which al­lows sub­se­quent bunches to pen­e­trate deeper into the tar­get. Its proper sim­u­la­tion re­quires, there­fore, to se­quen­tially cou­ple an en­ergy-de­po­si­tion code and a hy­dro­dy­namic code for the dif­fer­ent tar­get den­si­ties. This paper de­scribes a method to ef­fi­ciently cou­ple the sim­u­la­tions codes Au­to­dyn and FLUKA based on au­to­matic den­sity as­sign­ment and input file gen­er­a­tion, and pre­sents the re­sults achieved for a sam­ple case.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB024  
About • paper received ※ 19 May 2021       paper accepted ※ 05 July 2021       issue date ※ 28 August 2021  
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