IPAC2021 - List of Authors (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
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)