IPAC2018 - List of Authors (Senaj, V.)

Paper	Title	Page
MOPMF062	Upgrade of the Dilution System for HL-LHC	261
	C. Wiesner, W. Bartmann, C. Bracco, M. Calviani, E. Carlier, L. Ducimetière, M.I. Frankl, M.A. Fraser, S.S. Gilardoni, B. Goddard, T. Kramer, A. Lechner, N. Magnin, A. Perillo-Marcone, T. Polzin, E. Renner, V. Senaj CERN, Geneva, Switzerland
	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
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF063	Asynchronous Beam Dump Tests at LHC	265
	C. Wiesner, W. Bartmann, C. Bracco, E. Carlier, L. Ducimetière, M.I. Frankl, M.A. Fraser, B. Goddard, C. Heßler, T. Kramer, A. Lechner, N. Magnin, V. Senaj, D. Wollmann CERN, Geneva, Switzerland
	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
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF058	Optimization of the FCC-hh Beam Extraction System Regarding Failure Avoidance and Mitigation	850
	E. Renner, M.J. Barnes, W. Bartmann, F. Burkart, E. Carlier, L. Ducimetière, B. Goddard, T. Kramer, A. Lechner, N. Magnin, V. Senaj, J.A. Uythoven, P. Van Trappen, C. Wiesner CERN, Geneva, Switzerland
	A core part of the Future Circular Collider (FCC) study is a high energy hadron-hadron collider with a circumference of nearly 100~km and a center of mass beam energy of 100~TeV. The energy stored in one beam at top energy is 8.3~GJ, more than 20 times that of the LHC beams. Due to the large damage potential of the FCC-hh beam, the design of the beam extraction system is dominated by machine protection considerations and the requirement of avoiding any material damage in case of an asynchronous beam dump. Erratic operation of one or more extraction kickers is a main contributor to asynchronous beam dumps. The presented study shows ways to reduce the probability and mitigate the impact of erratic kicker switching. Key proposals to achieve this include layout considerations, different hardware options and alternative reaction strategies in case of erratic extraction kicker occurrence. Based on these concepts, different solutions are evaluated and an optimized design for the FCC-hh extraction system is proposed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF058
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF060	Injection and Dump Systems for a 13.5 TeV Hadron Synchrotron HE-LHC	858
	W. Bartmann, M.J. Barnes, L. Ducimetière, B. Goddard, M. Hofer, T. Kramer, A. Lechner, E. Renner, A. Sanz Ull, V. Senaj, L.S. Stoel, C. Wiesner CERN, Geneva, Switzerland
	One option for a future circular collider at CERN is to build a 13.5 TeV hadron synchrotron, or High Energy LHC (HE-LHC) in the LHC tunnel. Injection and dump systems will have to be upgraded to cope with the higher beam rigidity and increased damage potential of the beam. The required modifications of the beam transfer hardware are highlighted in view of technology advancements in the field of kicker switch technology. An optimised straight section optics is shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF060
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF086	Eradication of Mercury Ignitron from the 400 kA Magnetic Horn Pulse Generator for CERN Antiproton Decelerator	2586
	V. Namora, M. Calviani, L. Ducimetière, P. Faure, L.E. Fernandez, G. Gräwer, V. Senaj CERN, Geneva, Switzerland
	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF086
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Upgrade of the Dilution System for HL-LHC

261

C. Wiesner, W. Bartmann, C. Bracco, M. Calviani, E. Carlier, L. Ducimetière, M.I. Frankl, M.A. Fraser, S.S. Gilardoni, B. Goddard, T. Kramer, A. Lechner, N. Magnin, A. Perillo-Marcone, T. Polzin, E. Renner, V. Senaj
CERN, Geneva, Switzerland

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

Export •

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

MOPMF063

Asynchronous Beam Dump Tests at LHC

265

C. Wiesner, W. Bartmann, C. Bracco, E. Carlier, L. Ducimetière, M.I. Frankl, M.A. Fraser, B. Goddard, C. Heßler, T. Kramer, A. Lechner, N. Magnin, V. Senaj, D. Wollmann
CERN, Geneva, Switzerland

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

Export •

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

TUPAF058

Optimization of the FCC-hh Beam Extraction System Regarding Failure Avoidance and Mitigation

850

E. Renner, M.J. Barnes, W. Bartmann, F. Burkart, E. Carlier, L. Ducimetière, B. Goddard, T. Kramer, A. Lechner, N. Magnin, V. Senaj, J.A. Uythoven, P. Van Trappen, C. Wiesner
CERN, Geneva, Switzerland

A core part of the Future Circular Collider (FCC) study is a high energy hadron-hadron collider with a circumference of nearly 100~km and a center of mass beam energy of 100~TeV. The energy stored in one beam at top energy is 8.3~GJ, more than 20 times that of the LHC beams. Due to the large damage potential of the FCC-hh beam, the design of the beam extraction system is dominated by machine protection considerations and the requirement of avoiding any material damage in case of an asynchronous beam dump. Erratic operation of one or more extraction kickers is a main contributor to asynchronous beam dumps. The presented study shows ways to reduce the probability and mitigate the impact of erratic kicker switching. Key proposals to achieve this include layout considerations, different hardware options and alternative reaction strategies in case of erratic extraction kicker occurrence. Based on these concepts, different solutions are evaluated and an optimized design for the FCC-hh extraction system is proposed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF058

Export •

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

TUPAF060

Injection and Dump Systems for a 13.5 TeV Hadron Synchrotron HE-LHC

858

W. Bartmann, M.J. Barnes, L. Ducimetière, B. Goddard, M. Hofer, T. Kramer, A. Lechner, E. Renner, A. Sanz Ull, V. Senaj, L.S. Stoel, C. Wiesner
CERN, Geneva, Switzerland

One option for a future circular collider at CERN is to build a 13.5 TeV hadron synchrotron, or High Energy LHC (HE-LHC) in the LHC tunnel. Injection and dump systems will have to be upgraded to cope with the higher beam rigidity and increased damage potential of the beam. The required modifications of the beam transfer hardware are highlighted in view of technology advancements in the field of kicker switch technology. An optimised straight section optics is shown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF060

Export •

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

WEPMF086

Eradication of Mercury Ignitron from the 400 kA Magnetic Horn Pulse Generator for CERN Antiproton Decelerator

2586

V. Namora, M. Calviani, L. Ducimetière, P. Faure, L.E. Fernandez, G. Gräwer, V. Senaj
CERN, Geneva, Switzerland

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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF086

Export •

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