IPAC2014 - Classification: 07 Accelerator Technology Main Systems / T23 Machine Protection

Paper	Title	Page
THPRO126	Implementation of Machine Protection System for the Taiwan Photon Source	3189
	C.Y. Liao, J. Chen, Y.-S. Cheng, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Wu NSRRC, Hsinchu, Taiwan
	The Taiwan Photon Source (TPS) is being constructed at the campus of the NSRRC (National Synchrotron Radiation Research Center) and commissioning expected in 2014. In order to prevent damage to accelerator components induced by various events, a global machine protection system (MPS) was installed and implemented. The MPS collect interlocks and beam dump requests from various system (thermo/flow of magnets, front-end, vacuum system, and orbit excursion interlock), perform decision, transmit dump beam request to E-Gun or RF system. The PLC based system with embedded EPICS IOC was used as a slow MPS which can delivery less than 8 msec reaction time. The fast MPS was dependent on event based timing system to deliver response time less than 5 μs. Trigger signal for post-mortem will also be distributed by the fast MPS. To ensure alive of the system, several self-diagnostics mechanisms include heartbeat and transient capture were implemented and tested. The MPS architecture, installation, and validation test results were presented in this report.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO126
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THPRI021	Implementation of a Direct Link between the LHC Beam Interlock System and the LHC Beam Dumping System Re-triggering Lines	3810
	S. Gabourin, E. Carlier, R. Denz, N. Magnin, J.A. Uythoven, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland M. Bartholdt, B. Bertsche, V. Vatansever, P. Zeiler Universität Stuttgart, Stuttgart, Germany
	To avoid damage of accelerator equipment due to impacting beam, the controlled removal of the LHC beams from the collider rings towards the dump blocks must be guaranteed at all times. When a beam dump is demanded, the Beam Interlock System communicates this request to the Trigger Synchronisation and Distribution System of the LHC Beam Dumping System. Both systems were built according to high reliability standards. To further reduce the risk of incapability to dump the beams in case of correlated failures in the Trigger Synchronisation and Distribution System, a new direct link from the Beam Interlock System to the re-triggering lines of the LHC Beam Dumping System will be implemented for the start-up with beam in 2015. The link represents a diverse redundancy to the current implementation, which should neither significantly increase the risk for so-called asynchronous beam dumps nor compromise machine availability. This paper describes the implementation choices of this link. Furthermore the results of a reliability analysis to quantify its impact on LHC machine availability are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI021
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THPRI091	Machine Protection Considerations for BERLinPro	3985
	S. Wesch, M. Abo-Bakr, M. Dirsat, G. Klemz, P. Kuske, A. Neumann, J. Rahn, T. Schneegans HZB, Berlin, Germany
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association The Berlin energy-recovery-linac project BERLinPro at the HZB is a 50 MeV ERL test facility, which addresses physical and technological questions for future superconducting rf based high brightness, high current electron beam sources. The combination of a 100 mA cw beam, electron bunches with normalized emittances lower than 1 mm mrad and the magnet optics of BERLinPro leads to power densities capable to harm the accelerator components within microseconds if total beam loss occurs. Furthermore, continuous beam loss on the level of 10^-5 has to be controlled to avoid activation and to protect the SRF, beam diagnostics and other infrastructure components. In this paper, we present the evaluation of the required key parameters of the BERLinPro machine protection system and present its first conceptual design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI091
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THPRI093	CSCM: EXPERIMENTAL AND SIMULATION RESULTS	3988
	S. Rowan, B. Auchmann, K. Brodzinski, Z. Charifoulline, R. Denz, V. Roger, I. Romera, R. Schmidt, A.P. Siemko, J. Steckert, H. Thiesen, A.P. Verweij, G.P. Willering, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland H. Pfeffer Fermilab, Batavia, Illinois, USA
	The copper-stabilizer continuity measurement - or CSCM - was devised to obtain a direct and complete qualification of the continuity in the 13 kA bypass circuits of the LHC, especially in the copper-stabilizer of the busbar joints and the bolted connections in the diode-leads. The circuit under test is brought to ~20 K, a voltage is applied to open the diodes, and the low-inductance circuit is powered with a pre-defined series of current profiles. The profiles are designed to successively increase the thermal load on the busbar joints up to a level that corresponds to worst-case operating conditions at nominal energy. In this way, the circuit is tested for thermal runaways in the joints - the very process that could prove catastrophic if it occurred under nominal conditions with the full circuit energy. Surveillance software and a numerical model were devised to carry out the analysis and ensure complete protection of the circuit from over-heating. A type test of the CSCM was successfully carried out in April 2013 on one main dipole and one main quadrupole circuit of the LHC. This paper describes the analysis procedure, the numerical model, and results of this first type test.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI093
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THPRI094	MadX Tracking Simulations to Determine the Beam loss Distributions for the LHC Quench Tests with ADT Excitation	3991
	V. Chetvertkova, B. Auchmann, T. Bär, W. Höfle, A. Priebe, M. Sapinski, R. Schmidt, A.P. Verweij, D. Wollmann CERN, Geneva, Switzerland
	Quench tests with stored beam were performed in 2013 with one of the LHC main focusing quadrupoles to experimentally verify the quench levels for beam losses in the time scales from a few milliseconds to several seconds. A novel technique combining a 3-corrector orbital bump and transverse-damper kicks was used for inducing the beam losses. MadX tracking simulations were an essential step for determining the spatial and angular beam loss distributions during the experiment. These were then used as input for further energy-deposition and quench-level calculations. In this paper the simulated beam-loss distributions for the respective time scales and experimental parameters are presented. Furthermore the sensitivity of the obtained loss-distributions to the variation of key input parameters, which were measured during the experiment, is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI094
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THPRI095	Testing Quality and Metrics for the LHC Magnet Powering System throughout Past and Future Commissioning	3995
	D. Anderson, M. Audrain, Z. Charifoulline, M. Dragu, K. Fuchsberger, J.C. Garnier, A.A. Gorzawski, M. Koza, K.H. Krol, S. Rowan, K. Stamos, M. Zerlauth CERN, Geneva, Switzerland
	The LHC magnet powering system is comprised of thousands of individual components to assure a safe operation when operating with stored energies as high as 10GJ in the superconducting LHC magnets. Each of these components has to be thoroughly commissioned following interventions and machine shutdown periods to assure their protection function in case of powering failures. As well as a dependable tracking of test executions it is vital that the executed commissioning steps and applied analysis criteria adequately represent the operational state of each component. The Accelerator Testing (AccTesting) framework in combination with a domain specific analysis language provides the means to quantify and improve the quality of analysis for future campaigns. Dedicated tools were developed to analyse in detail the reasons for failures and success of commissioning steps in past campaigns and to compare the results with newly developed quality metrics. Observed shortcomings and discrepancies are used to propose additional verification and mitigation for future campaigns in an effort to improve the testing quality and hence assure the overall dependability of subsequent operational periods.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI095
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THPRI096	Use of Silicon Carbide as Beam Intercepting Device Material: Tests, Issues and Numerical Simulations	3998
	C. Maglioni, M. Delonca, M. Gil Costa, A. Vacca CERN, Geneva, Switzerland
	Silicon Carbide (SiC) stands as one of the most promising ceramic material with respect to its thermal shock resistance and mechanical strengths. It has hence been considered as candidate material for the development of higher performance beam intercepting devices at CERN. Its brazing with a metal counterpart has been tested and characterized by means of microstructural and ultrasound techniques. Despite the very positive results, its use has to be evaluated with care, due to the strong evidence in literature of large and permanent volumetric expansion, called swelling, under the effect of neutron and ion irradiation. This may cause premature and sudden failure of components, and can be mitigated to some extent by operating at high temperature. For this reason limited information is available for irradiation below 100°C, which is the typical temperature reached in intercepting devices like dumps or collimators. This paper describes the brazing campaign carried out at CERN, the results, and the theoretical and numerical approach used to characterize the extent of the swelling phenomenon with radiation, as well as the p⁺ irradiation test program to be conducted in the next future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI096
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THPRI097	A Retrospective View to the Magnet Interlock Systems at CERN	4001
	I. Romera, P. Dahlen, R. Mompo, B. Puccio, M. Zerlauth CERN, Geneva, Switzerland
	Several thousands of both, superconducting and normal conducting magnets are in charge of guiding the particle beams in CERN’s accelerator complex. In order to protect the magnet and powering equipment from damage, dedicated magnet interlock and protection systems are deployed throughout the various accelerators and transfer lines. These systems have worked extremely well during the first years of LHC operation, providing highly dependable interlocking of magnet powering based on industrial COTS components. This paper reviews the performance of the more than 70 individual installations during the first LHC running period and compares the operational experience with the initial expectations of dependability. Additional improvements required to address specific operational needs and observed shortcomings are presented. Finally, we review the existing magnet interlock infrastructure in the LHC injector complex and the ongoing renovation works during the first long shutdown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI097
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THPRI098	Brazing and Helium Leaking Test for High Heat Load Components in the Taiwan Photon Source	4004
	P.A. Lin, C.K. Kuan, T.Y. Lee, H.Y. Lin, I.C. Sheng NSRRC, Hsinchu, Taiwan
	Taiwan Photon Source is the second accelerator constructed by National Synchrotron Radiation Research Center (NSRRC). With 3GeV, 500mA, this facility will generate extremely high synchrotron radiation and most of the power load will be shadowed at front end in order to shape final confining beam size for beam lines users. The high heat load components are known to be the critical parts to absorb the unwanted energy. In order to practically distribute high density power along each high heat load components, several absorbers are introduced. Namely, primary mask, main mask, photon absorber and slits. The manufacturing process such as UHV chemical cleaning, brazing and helium leaking test will be described in this report.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI098
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Paper

Title

Page

Implementation of Machine Protection System for the Taiwan Photon Source

3189

C.Y. Liao, J. Chen, Y.-S. Cheng, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Wu
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source (TPS) is being constructed at the campus of the NSRRC (National Synchrotron Radiation Research Center) and commissioning expected in 2014. In order to prevent damage to accelerator components induced by various events, a global machine protection system (MPS) was installed and implemented. The MPS collect interlocks and beam dump requests from various system (thermo/flow of magnets, front-end, vacuum system, and orbit excursion interlock), perform decision, transmit dump beam request to E-Gun or RF system. The PLC based system with embedded EPICS IOC was used as a slow MPS which can delivery less than 8 msec reaction time. The fast MPS was dependent on event based timing system to deliver response time less than 5 μs. Trigger signal for post-mortem will also be distributed by the fast MPS. To ensure alive of the system, several self-diagnostics mechanisms include heartbeat and transient capture were implemented and tested. The MPS architecture, installation, and validation test results were presented in this report.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO126

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THPRI021

Implementation of a Direct Link between the LHC Beam Interlock System and the LHC Beam Dumping System Re-triggering Lines

3810

S. Gabourin, E. Carlier, R. Denz, N. Magnin, J.A. Uythoven, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland
M. Bartholdt, B. Bertsche, V. Vatansever, P. Zeiler
Universität Stuttgart, Stuttgart, Germany

To avoid damage of accelerator equipment due to impacting beam, the controlled removal of the LHC beams from the collider rings towards the dump blocks must be guaranteed at all times. When a beam dump is demanded, the Beam Interlock System communicates this request to the Trigger Synchronisation and Distribution System of the LHC Beam Dumping System. Both systems were built according to high reliability standards. To further reduce the risk of incapability to dump the beams in case of correlated failures in the Trigger Synchronisation and Distribution System, a new direct link from the Beam Interlock System to the re-triggering lines of the LHC Beam Dumping System will be implemented for the start-up with beam in 2015. The link represents a diverse redundancy to the current implementation, which should neither significantly increase the risk for so-called asynchronous beam dumps nor compromise machine availability. This paper describes the implementation choices of this link. Furthermore the results of a reliability analysis to quantify its impact on LHC machine availability are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI021

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THPRI091

Machine Protection Considerations for BERLinPro

3985

S. Wesch, M. Abo-Bakr, M. Dirsat, G. Klemz, P. Kuske, A. Neumann, J. Rahn, T. Schneegans
HZB, Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association
The Berlin energy-recovery-linac project BERLinPro at the HZB is a 50 MeV ERL test facility, which addresses physical and technological questions for future superconducting rf based high brightness, high current electron beam sources. The combination of a 100 mA cw beam, electron bunches with normalized emittances lower than 1 mm mrad and the magnet optics of BERLinPro leads to power densities capable to harm the accelerator components within microseconds if total beam loss occurs. Furthermore, continuous beam loss on the level of 10^-5 has to be controlled to avoid activation and to protect the SRF, beam diagnostics and other infrastructure components. In this paper, we present the evaluation of the required key parameters of the BERLinPro machine protection system and present its first conceptual design.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI091

Export •

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

THPRI093

CSCM: EXPERIMENTAL AND SIMULATION RESULTS

3988

S. Rowan, B. Auchmann, K. Brodzinski, Z. Charifoulline, R. Denz, V. Roger, I. Romera, R. Schmidt, A.P. Siemko, J. Steckert, H. Thiesen, A.P. Verweij, G.P. Willering, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland
H. Pfeffer
Fermilab, Batavia, Illinois, USA

The copper-stabilizer continuity measurement - or CSCM - was devised to obtain a direct and complete qualification of the continuity in the 13 kA bypass circuits of the LHC, especially in the copper-stabilizer of the busbar joints and the bolted connections in the diode-leads. The circuit under test is brought to ~20 K, a voltage is applied to open the diodes, and the low-inductance circuit is powered with a pre-defined series of current profiles. The profiles are designed to successively increase the thermal load on the busbar joints up to a level that corresponds to worst-case operating conditions at nominal energy. In this way, the circuit is tested for thermal runaways in the joints - the very process that could prove catastrophic if it occurred under nominal conditions with the full circuit energy. Surveillance software and a numerical model were devised to carry out the analysis and ensure complete protection of the circuit from over-heating. A type test of the CSCM was successfully carried out in April 2013 on one main dipole and one main quadrupole circuit of the LHC. This paper describes the analysis procedure, the numerical model, and results of this first type test.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI093

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

THPRI094

MadX Tracking Simulations to Determine the Beam loss Distributions for the LHC Quench Tests with ADT Excitation

3991

V. Chetvertkova, B. Auchmann, T. Bär, W. Höfle, A. Priebe, M. Sapinski, R. Schmidt, A.P. Verweij, D. Wollmann
CERN, Geneva, Switzerland

Quench tests with stored beam were performed in 2013 with one of the LHC main focusing quadrupoles to experimentally verify the quench levels for beam losses in the time scales from a few milliseconds to several seconds. A novel technique combining a 3-corrector orbital bump and transverse-damper kicks was used for inducing the beam losses. MadX tracking simulations were an essential step for determining the spatial and angular beam loss distributions during the experiment. These were then used as input for further energy-deposition and quench-level calculations. In this paper the simulated beam-loss distributions for the respective time scales and experimental parameters are presented. Furthermore the sensitivity of the obtained loss-distributions to the variation of key input parameters, which were measured during the experiment, is discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI094

Export •

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

THPRI095

Testing Quality and Metrics for the LHC Magnet Powering System throughout Past and Future Commissioning

3995

D. Anderson, M. Audrain, Z. Charifoulline, M. Dragu, K. Fuchsberger, J.C. Garnier, A.A. Gorzawski, M. Koza, K.H. Krol, S. Rowan, K. Stamos, M. Zerlauth
CERN, Geneva, Switzerland

The LHC magnet powering system is comprised of thousands of individual components to assure a safe operation when operating with stored energies as high as 10GJ in the superconducting LHC magnets. Each of these components has to be thoroughly commissioned following interventions and machine shutdown periods to assure their protection function in case of powering failures. As well as a dependable tracking of test executions it is vital that the executed commissioning steps and applied analysis criteria adequately represent the operational state of each component. The Accelerator Testing (AccTesting) framework in combination with a domain specific analysis language provides the means to quantify and improve the quality of analysis for future campaigns. Dedicated tools were developed to analyse in detail the reasons for failures and success of commissioning steps in past campaigns and to compare the results with newly developed quality metrics. Observed shortcomings and discrepancies are used to propose additional verification and mitigation for future campaigns in an effort to improve the testing quality and hence assure the overall dependability of subsequent operational periods.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI095

Export •

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

THPRI096

Use of Silicon Carbide as Beam Intercepting Device Material: Tests, Issues and Numerical Simulations

3998

C. Maglioni, M. Delonca, M. Gil Costa, A. Vacca
CERN, Geneva, Switzerland

Silicon Carbide (SiC) stands as one of the most promising ceramic material with respect to its thermal shock resistance and mechanical strengths. It has hence been considered as candidate material for the development of higher performance beam intercepting devices at CERN. Its brazing with a metal counterpart has been tested and characterized by means of microstructural and ultrasound techniques. Despite the very positive results, its use has to be evaluated with care, due to the strong evidence in literature of large and permanent volumetric expansion, called swelling, under the effect of neutron and ion irradiation. This may cause premature and sudden failure of components, and can be mitigated to some extent by operating at high temperature. For this reason limited information is available for irradiation below 100°C, which is the typical temperature reached in intercepting devices like dumps or collimators. This paper describes the brazing campaign carried out at CERN, the results, and the theoretical and numerical approach used to characterize the extent of the swelling phenomenon with radiation, as well as the p⁺ irradiation test program to be conducted in the next future.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI096

Export •

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

THPRI097

A Retrospective View to the Magnet Interlock Systems at CERN

4001

I. Romera, P. Dahlen, R. Mompo, B. Puccio, M. Zerlauth
CERN, Geneva, Switzerland

Several thousands of both, superconducting and normal conducting magnets are in charge of guiding the particle beams in CERN’s accelerator complex. In order to protect the magnet and powering equipment from damage, dedicated magnet interlock and protection systems are deployed throughout the various accelerators and transfer lines. These systems have worked extremely well during the first years of LHC operation, providing highly dependable interlocking of magnet powering based on industrial COTS components. This paper reviews the performance of the more than 70 individual installations during the first LHC running period and compares the operational experience with the initial expectations of dependability. Additional improvements required to address specific operational needs and observed shortcomings are presented. Finally, we review the existing magnet interlock infrastructure in the LHC injector complex and the ongoing renovation works during the first long shutdown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI097

Export •

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

THPRI098

Brazing and Helium Leaking Test for High Heat Load Components in the Taiwan Photon Source

4004

P.A. Lin, C.K. Kuan, T.Y. Lee, H.Y. Lin, I.C. Sheng
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source is the second accelerator constructed by National Synchrotron Radiation Research Center (NSRRC). With 3GeV, 500mA, this facility will generate extremely high synchrotron radiation and most of the power load will be shadowed at front end in order to shape final confining beam size for beam lines users. The high heat load components are known to be the critical parts to absorb the unwanted energy. In order to practically distribute high density power along each high heat load components, several absorbers are introduced. Namely, primary mask, main mask, photon absorber and slits. The manufacturing process such as UHV chemical cleaning, brazing and helium leaking test will be described in this report.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI098

Export •

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