IPAC2016 - List of Authors (Wollmann, D.)

Paper	Title	Page
MOPMR031	Investigation of Injection Losses at the Large Hadron Collider with Diamond Based Particle Detectors	310
	O. Stein, W. Bartmann, F. Burkart, B. Dehning, V. Kain, R. Schmidt, D. Wollmann CERN, Geneva, Switzerland E. Griesmayer CIVIDEC Instrumentation, Wien, Austria
	During the operation of the Large Hadron Collider (LHC) in 2015, increased injection losses were observed. To minimize stress on accelerator components in the injection regions of the LHC and to guarantee an efficient operation these losses needed to be understood and possible mitigation techniques should be studied. Measurements with diamond particle detectors revealed the loss structure with ns-resolution for the first time. Based on these measurements, recaptured beam from the Super Proton Synchrotron (SPS) surrounding the nominal bunch train was identified as the major contributor to the injection loss signals. Methods to reduce the recaptured beam in the SPS were successfully tested and verified with the diamond particle detectors. In this paper the detection and classification of LHC injection losses are described. The methods to reduce these losses and verification measurements are presented and discussed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR031
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TUPMB038	Degradation of the Insulation of the LHC Main Dipole Cable when Exposed to High Temperatures	1186
	V. Raginel, B. Auchmann, D. Kleiven, R. Schmidt, A.P. Verweij, D. Wollmann CERN, Geneva, Switzerland
	Funding: Research supported by the High Luminosity LHC project The energy stored in the LHC beams is substantial and requires a complex machine protection system to protect the equipment. Despite efficient beam absorbers, several failure modes lead to some limited beam impact on superconducting magnets. Thus it is required to understand the damage mechanisms and limits of superconducting magnets due to instantaneous beam impact. This becomes even more important due to the future upgrade of CERNs injector chain for the LHC that will lead to an increase of the beam brightness. A roadmap to perform damage tests on magnet parts has been presented previously. The polyimide insulation of the superconducting cable is identified as one of the critical elements of the magnet. In this contribution, the experimental setup to measure the insulation degradation of LHC main dipole cables due to exposure to high temperature is described. Compressed stacks of insulated Nb-Ti cables have been exposed to a heat treatment within an Argon atmosphere. After each heat treatment, high-voltage measurements verified the dielectric strength of the insulation. The results of this experiment provide an upper damage limit of superconducting magnets due to beam impact. Experimental Setups to Determine the Damage Limit of Superconducting Magnets for Instantaneous Beam Losses, V. Raginel et al, IPAC'15
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB038
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TUPMB040	LHC Accelerator Fault Tracker - First Experience	1190
	A. Apollonio, L. Ponce, C. Roderick, R. Schmidt, B. Todd, D. Wollmann CERN, Geneva, Switzerland
	Availability is one of the key performance indicators of LHC operation, being directly correlated with integrated luminosity production. An effective tool for availability tracking is a necessity to ensure a coherent capture of fault information and relevant dependencies on operational modes and beam parameters. At the beginning of LHC Run 2 in 2015, the Accelerator Fault Tracking (AFT) tool was deployed at CERN to track faults or events affecting LHC operation. Information derived from the AFT is crucial for the identification of areas to improve LHC availability, and hence LHC physics production. For the 2015 run, the AFT has been used by members of the CERN Availability Working Group, LHC Machine coordinators and equipment owners to identify the main contributors to downtime and to understand the evolution of LHC availability throughout the year. In this paper the 2015 experience with the AFT for availability tracking is summarised and an overview of the first results as well as an outlook to future developments is given.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB040
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THPOY044	Experimental Setup to Measure the Damage Limits of Superconducting Magnets due to Beam Impact at CERN's HiRadMat Facility	4200
	D. Kleiven Kleiven, David, Geneva, Switzerland B. Auchmann, V. Raginel, R. Schmidt, A.P. Verweij, D. Wollmann CERN, Geneva, Switzerland
	Funding: Research supported by the High Luminosity LHC project The future upgrade of CERN's injector chain for the Large Hadron Collider (LHC) will lead to an increase of the beam brightness in the LHC. Beam absorbers are capturing missteered beams, but some limited beam impact on superconducting magnets can hardly be avoided. Therefore, it is planned to measure the damage limits of superconducting magnet components due to beam impact at CERN's HiRad- Mat facility using the 440 GeV proton beam from the Super Proton Synchrotron. Two experiments are proposed. One at ambient and one at cryogenic temperatures, where several pre-stressed stacks of LHC main dipole Nb-Ti cables and some single strands will be irradiated with varying beam intensities. The electrical integrity and the degradation of critical current will be measured after the removal from the HiRadMat facility. In the cold experiment some sample magnets will be added and the degradation of performance will be monitored online. In this contribution the experimental setup of the first experiment, including the sample container and cable stacks, is presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY044
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THPOY045	Commissioning of the Machine Protection Systems of the Large Hadron Collider Following its First Long Shutdown	4203
	D. Wollmann, R. Schmidt, J.A. Uythoven, J. Wenninger, M. Zerlauth CERN, Geneva, Switzerland
	During the first long shutdown of the Large Hadron Collider (LHC) extending for more than 18 months, most Machine Protection Systems (MPS) have undergone significant changes, and upgrades. A full re-commissioning of the MPS was performed at the end of the shutdown and during the LHC beam commissioning in 2015. To verify the correct functioning of all protection-relevant systems with beam, a step-wise intensity ramp-up was performed, reaching at the end of 2015 a record stored beam energy of ~280 MJ per beam, nearly 80% of the value in the design report. This contribution summarizes the results of the MPS commissioning, the intensity ramp-up and the continuous follow-up during operation, focusing mainly on near misses and false triggers and their proposed mitigations. A strategy to minimize risks during machine development periods for future operation of the LHC, when the protection parameters are modified for several tests, is discussed. The machine protection strategy for the LHC run in 2016 is presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY045
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Paper

Title

Page

Investigation of Injection Losses at the Large Hadron Collider with Diamond Based Particle Detectors

310

O. Stein, W. Bartmann, F. Burkart, B. Dehning, V. Kain, R. Schmidt, D. Wollmann
CERN, Geneva, Switzerland
E. Griesmayer
CIVIDEC Instrumentation, Wien, Austria

During the operation of the Large Hadron Collider (LHC) in 2015, increased injection losses were observed. To minimize stress on accelerator components in the injection regions of the LHC and to guarantee an efficient operation these losses needed to be understood and possible mitigation techniques should be studied. Measurements with diamond particle detectors revealed the loss structure with ns-resolution for the first time. Based on these measurements, recaptured beam from the Super Proton Synchrotron (SPS) surrounding the nominal bunch train was identified as the major contributor to the injection loss signals. Methods to reduce the recaptured beam in the SPS were successfully tested and verified with the diamond particle detectors. In this paper the detection and classification of LHC injection losses are described. The methods to reduce these losses and verification measurements are presented and discussed.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR031

Export •

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

TUPMB038

Degradation of the Insulation of the LHC Main Dipole Cable when Exposed to High Temperatures

1186

V. Raginel, B. Auchmann, D. Kleiven, R. Schmidt, A.P. Verweij, D. Wollmann
CERN, Geneva, Switzerland

Funding: Research supported by the High Luminosity LHC project
The energy stored in the LHC beams is substantial and requires a complex machine protection system to protect the equipment. Despite efficient beam absorbers, several failure modes lead to some limited beam impact on superconducting magnets. Thus it is required to understand the damage mechanisms and limits of superconducting magnets due to instantaneous beam impact. This becomes even more important due to the future upgrade of CERNs injector chain for the LHC that will lead to an increase of the beam brightness. A roadmap to perform damage tests on magnet parts has been presented previously*. The polyimide insulation of the superconducting cable is identified as one of the critical elements of the magnet. In this contribution, the experimental setup to measure the insulation degradation of LHC main dipole cables due to exposure to high temperature is described. Compressed stacks of insulated Nb-Ti cables have been exposed to a heat treatment within an Argon atmosphere. After each heat treatment, high-voltage measurements verified the dielectric strength of the insulation. The results of this experiment provide an upper damage limit of superconducting magnets due to beam impact.
* Experimental Setups to Determine the Damage Limit of Superconducting Magnets for Instantaneous Beam Losses, V. Raginel et al, IPAC'15

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB038

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TUPMB040

LHC Accelerator Fault Tracker - First Experience

1190

A. Apollonio, L. Ponce, C. Roderick, R. Schmidt, B. Todd, D. Wollmann
CERN, Geneva, Switzerland

Availability is one of the key performance indicators of LHC operation, being directly correlated with integrated luminosity production. An effective tool for availability tracking is a necessity to ensure a coherent capture of fault information and relevant dependencies on operational modes and beam parameters. At the beginning of LHC Run 2 in 2015, the Accelerator Fault Tracking (AFT) tool was deployed at CERN to track faults or events affecting LHC operation. Information derived from the AFT is crucial for the identification of areas to improve LHC availability, and hence LHC physics production. For the 2015 run, the AFT has been used by members of the CERN Availability Working Group, LHC Machine coordinators and equipment owners to identify the main contributors to downtime and to understand the evolution of LHC availability throughout the year. In this paper the 2015 experience with the AFT for availability tracking is summarised and an overview of the first results as well as an outlook to future developments is given.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB040

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THPOY044

Experimental Setup to Measure the Damage Limits of Superconducting Magnets due to Beam Impact at CERN's HiRadMat Facility

4200

D. Kleiven
Kleiven, David, Geneva, Switzerland
B. Auchmann, V. Raginel, R. Schmidt, A.P. Verweij, D. Wollmann
CERN, Geneva, Switzerland

Funding: Research supported by the High Luminosity LHC project
The future upgrade of CERN's injector chain for the Large Hadron Collider (LHC) will lead to an increase of the beam brightness in the LHC. Beam absorbers are capturing missteered beams, but some limited beam impact on superconducting magnets can hardly be avoided. Therefore, it is planned to measure the damage limits of superconducting magnet components due to beam impact at CERN's HiRad- Mat facility using the 440 GeV proton beam from the Super Proton Synchrotron. Two experiments are proposed. One at ambient and one at cryogenic temperatures, where several pre-stressed stacks of LHC main dipole Nb-Ti cables and some single strands will be irradiated with varying beam intensities. The electrical integrity and the degradation of critical current will be measured after the removal from the HiRadMat facility. In the cold experiment some sample magnets will be added and the degradation of performance will be monitored online. In this contribution the experimental setup of the first experiment, including the sample container and cable stacks, is presented.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY044

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THPOY045

Commissioning of the Machine Protection Systems of the Large Hadron Collider Following its First Long Shutdown

4203

D. Wollmann, R. Schmidt, J.A. Uythoven, J. Wenninger, M. Zerlauth
CERN, Geneva, Switzerland

During the first long shutdown of the Large Hadron Collider (LHC) extending for more than 18 months, most Machine Protection Systems (MPS) have undergone significant changes, and upgrades. A full re-commissioning of the MPS was performed at the end of the shutdown and during the LHC beam commissioning in 2015. To verify the correct functioning of all protection-relevant systems with beam, a step-wise intensity ramp-up was performed, reaching at the end of 2015 a record stored beam energy of ~280 MJ per beam, nearly 80% of the value in the design report. This contribution summarizes the results of the MPS commissioning, the intensity ramp-up and the continuous follow-up during operation, focusing mainly on near misses and false triggers and their proposed mitigations. A strategy to minimize risks during machine development periods for future operation of the LHC, when the protection parameters are modified for several tests, is discussed. The machine protection strategy for the LHC run in 2016 is presented.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY045

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