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Workshop on Beam-Induced Quenches
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Europe/Zurich
30/7-018 - Kjell Johnsen Auditorium (CERN)
Anton Lechner
(CERN),
Belen Maria Salvachua Ferrando
(CERN),
Bernhard Auchmann
(CERN),
Mariusz Sapinski
(CERN)
Description
Overview:
During Run 1, beam-induced quenches have not yet been a limiting factor in the operation the LHC. After the long shutdown, the LHC will operate with much smaller operational margins, and at two thirds higher beam energy. Losses downstream of collimation, debris from the interaction regions, and, last not least, the occurrence of dust particles crossing the beams in arbitrary locations around the ring (colloquially called U.F.O.s, unidentified falling objects), will make beam-induced quenches a much more likely scenario during Run 2.
In view of this, controlled beam-loss experiments have been carried out before the long shutdown, in order to gather data that allows extrapolating to operation at 6.5 TeV. Detailed analysis of the events has been carried out throughout the long shut down. It has revealed strengths and weaknesses in our understanding of beam-loss events and beam-induced quenches. Based on this experience, we have launched the effort to update the settings of beam-loss monitors around the ring.
It is the aim of this workshop to survey the operational experience of superconducting accelerators and transfer lines, analyze the results and lessons learned of beam-loss experiments at the LHC, scrutinize the status of numerical models for the prediction of quench levels in superconducting accelerator magnets, and review the strategies for beam-loss monitoring in the LHC after the long shutdown. Moreover, we intend to stimulate a discussion on road-maps for the experimental validation of numerical and analytical models for quench- and damage levels for transient beam losses in accelerator magnets.
Organizers: B. Auchmann, A. Lechner, B. Salvachua, M. Sapinski
Proceedings Editor: E. Todesco
Administration: S. Sapountzi
Participants
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Registration 30/7-018 - Kjell Johnsen Auditorium
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Welcome Message 30/7-018 - Kjell Johnsen AuditoriumConvener: Dr Andrzej Siemko (CERN)
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Session 1: Operational Experience with Beam Losses and Beam-Induced Quenches 30/7-018 - Kjell Johnsen Auditorium
In this session the experience with beam-induced quenches in large superconducting accelerators and transfer lines is presented. Topics of interest include: beam loss mechanisms, statistics and analysis of beam-loss events, BLM systems parameters, threshold-setting strategies, and quench-level models as well as damage-level models for transient beam losses in SC magnets.
Conveners: Dr Andrzej Siemko (CERN), Dr Mariusz Sapinski (CERN)- 1
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Beam Losses and beam induced quenches at the LHC 30/7-018 - Kjell Johnsen AuditoriumSpeaker: Belen Maria Salvachua Ferrando (CERN)
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10:40
Coffee 30/7-018 - Kjell Johnsen Auditorium (CERN)
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Beam losses at Hera and Tevatron 30/7-018 - Kjell Johnsen Auditoriumwith contributions from Kay Wittenburg (DESY) and Nikolai Mokhov (FNAL)Speaker: Dr Mariusz Sapinski (CERN)
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SIS100 - Estimations of Systematic and Spurious Beam Losses and Quench Protection 30/7-018 - Kjell Johnsen AuditoriumSpeaker: Carsten Omet (GSI Helmholtzzentrum für Schwerionenforschung mbH)
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Beam-Losses and Beam-Induced Quenches at BNL 30/7-018 - Kjell Johnsen AuditoriumSpeaker: Mei Bai (Brookhaven National Laboratory)
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13:00
Lunch Break
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Session 2: Quench Tests at the LHC 30/7-018 - Kjell Johnsen Auditorium
This session is devoted to a series of controlled beam-loss experiments performed in the LHC during Run1. Loss durations ranged from single-turn losses to over 20-s loss duration. The experimental setup is introduced, followed by the main aspects of BIQ analysis: loss pattern estimation, particle shower simulations, and electro-thermal calculations. Analysis results and possible improvements for future experiments are discussed.
Conveners: Bernd Dehning (CERN), Dr Chiara Bracco (CERN)- 6
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Particle Tracking for Orbit-Bump Quench Tests at LHCSpeaker: Vera Chetvertkova (CERN)
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15:30
Coffee
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19:30
Dinner Halles de l'Ile (Geneva) (Other Institutes)
Halles de l'Ile (Geneva)
Other Institutes
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Session 3: Heat Transfer R&D 30/7-018 - Kjell Johnsen Auditorium
The aim of the session is to present the state of the art in the study of heat transport from superconducting cables to liquid helium. Numerical models will be discussed, as well as the latest results of experimental work. We aim for a lively discussion on future experimental work to validate numerical models in the highly-relevant millisecond-loss regime (UFO losses in the LHC). Moreover, we want to devote one slot to the conception of an experimental program towards validated damage-levels for fast beam-loss events in superconducting accelerator magnets.
Conveners: Bernardo Bordini (CERN), Dr Gerard Willering (CERN)- 12
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Possibilities of Finite Element Modelling for a Better Understanding of Heat Transfer in Rutherford-Type CablesThe results obtained with Finite Element models help to better understand the heat transfer mechanism in complex structures, like Nb-Ti Rutherford type cables. With FE models, it is possible to implement the real geometry with different levels of precision, giving the possibility to take into consideration the properties on interfaces between copper, helium and kapton, as well as phase changes in helium and the strongly non-linear behavior of HeII.Speaker: Erwin Roland Bielert (CERN)
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Modeling heat transfer to helium in the stability analysis of Rutherford cablesThe main experimental results on the transient heat transfer from solid surfaces to liquid helium are summarized. Models of these phenomena in stability analyses of superconducting wires and cables are presented. A focus on the quench analysis of Rutherford cables subjected to the external heat disturbance due to Beam Losses is presented, showing the impact on stability margin of the heat transfer towards interstitial helium and helium bath. The effects of the non-uniformity of the heat disturbance over the cable volume and of the heat and current redistribution between strands are shown by comparing models of increasing complexity.Speaker: Marco Breschi (U)
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10:40
Coffee
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Transient heat and mass transfer to superfluid helium Application to superconducting magnet coolingComprehending the cooling of superconducting magnets with superfluid helium requires the knowledge of heat and mass transfer in different size and time scales. Moreover, steady-state, transient and phase change must be considered in order to cover a wide spectrum of working conditions and thermal events to which these magnets are subjected. Focusing on the transient heat and mass transfer to superfluid helium for superconducting magnets cooling, we present a non-exhaustive review of experimental measurements and modellings in the ms to µs time scale. Heat transfer in different configurations (wire, channel, confined geometries…) will be covered as well as the surface heat transfer and the phase change. Some experimental and numerical studies directly related to the cooling of superconducting magnet in superfluid helium will be discussed in more details.Speakers: Bertrand Baudouy (CEA Saclay), Bertrand Baudouy (IRFU)
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Identification of Damage-Levels of SC Magnets for transient beam losses: Strategy and PlansSpeaker: Dr Daniel Wollmann (CERN)
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13:00
Lunch Break
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Session 4: LHC BLM Thresholds for Run 2 30/7-018 - Kjell Johnsen Auditorium
The aim of this session is to review the strategy for setting the LHC Beam Loss Monitors Thresholds after the long shutdown. The different involved teams will present a proposal for new BLM thresholds. This will cover losses from U.F.O.-type events, collimation-induced losses during proton and ion operation, losses at the triplets, and injection and dump losses.
Conveners: Dr Daniel Wollmann (CERN), Dr Roderik Bruce (CERN)- 19
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15:00
Coffee
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Session 5: Summary 30/7-018 - Kjell Johnsen Auditorium
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Sessions SummarySpeakers: Bernd Dehning (CERN), Dr Chiara Bracco (CERN), Dr Gerard Willering (CERN), Dr Mariusz Sapinski (CERN), Dr Roderik Bruce (CERN)
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Session 6: Experimental Roadmaps - Informal Brainstorming Continued Restaurant 1
Restaurant 1
CERN
For those keenly interested in continuing the discussion on experimental programs, we would like to provide a dinner date in CERN's restaurant 1.
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