Workshop on Linac Operation with Long Bunch Trains

22 Feb 2010, 09:00 → 24 Feb 2010, 13:05 Europe/Berlin

Sem. R. 1, Bldg. 1 (DESY)

John Carwardine (Argonne), Nicholas Walker (DESY), Siegfried Schreiber (DESY)

Large Superconducting linacs such as the European XFEL and the International Linear Collider will operate with long bunch trains and heavily beam-loaded accelerating cavities. This workshop will address the special challenges of operating such machines. A central feature of the program will be results and lessons learnt from the '9mA studies' at FLASH during September 2009, with one goal of the workshop being to develop plans for future studies at FLASH. The 9mA program was initiated jointly by DESY and ILC-GDE in order to achieve the following objectives:

• Demonstrate bunch-to-bunch beam energy uniformity and pulse to pulse beam energy stability with long pulses at full beam loading
• Characterise performance limitations at gradients approaching quench, including Control requirements for gradient overhead and RF power overhead
• Measure cryogenic loads (HOM absorber studies)

WORKSHOP OBJECTIVES

The workshop will address special issues associated with running long bunch trains in the FLASH linac at DESY. Central to the workshop will be the joint DESY-ILC '9mA studies program' and long bunch-train operation for the FLASH photon users. XFEL-related studies at FLASH will also be considered. Goals for the workshop can be broadly summarized as follows:

1. Review results and lessons learnt from the most recent 9mA studies period in Sept 09.
2. Explore strategies for efficiently re-establishing stable long bunch-train operation with currents from 1mA to 9mA
3. Explore strategies for characterizing LLRF stabilization of beam energy at the limits of RF power and cavity gradient
4. Develop proposals for future studies at FLASH and identify associated preparatory work

The program will include a review of FLASH operation with long bunch-trains for ILC- and XFEL-related accelerator studies and for photon science experiments. A major part of the workshop will be dedicated to working sessions developed around four thematic Working Groups, described below.

Working Groups

A full day of the workshop will be dedicated to working sessions developed around four thematic Working Groups. The working group themes are briefly described below. There will be joint working sessions of the various groups to cover overlapping topics.

Working Group #1: FLASH setup, tuning, and operation (Leaders: B. Faatz, J. Carwardine)

During the September 2009 studies, it took more than 10 shifts of expert tuning to achieve low-loss transmission of several hundred 3nC bunches. To make efficient use of future studies periods, it will be necessary to tune the machine reliably and consistently much more rapidly. This group will consider what is necessary to accomplish that, such as: identifying ‘golden’ working points using detailed information archived in the FLASH DAQ; tuning strategies; procedures and automation; parameter reproducibility and stability; diagnostics; accelerator modeling; extrapolation to XFEL. Differences between 1nC and 3nC bunch charges should be considered.

Working Group #2: FLASH feedback and control (Leaders: H. Schlarb, V. Ayvazyan)

Robust feedback systems are crucial achieving stable and repeatable performance. The LLRF systems regulate the cavity vector sums using feedback within the bunch train and by adjusting the RF drive waveforms pulse-to-pulse (‘adaptive feed forward’). Beam-based feedbacks are used to stabilize the bunch arrival times and compression factors at the end of the bunch compressor chicanes and the beam orbits from injector to beam dump. Topics for this group include: examining the performance and robustness of these feedback systems and considering possible improvements to algorithms and implementation; exception and error handling.

Working Group #3: ILC studies at FLASH (Leaders: N. Solyak, S. Michizono)

The FLASH 9mA study program was jointly initiated by DESY and the ILC Global Design Effort in order to demonstrate and study operation of the Tesla/ILC superconducting accelerating cavities with full beam loading and long bunch trains. The study program is focused on characterizing operations limitations to achieving ILC energy stability requirements for the main linac and bunch compressors: LLRF performance; accelerating cavity gradient operating margins; RF power operating margins. The group will evaluate data from the September studies and develop proposals for future future studies.

Working Group #4: DAQ and data analysis (Leaders: T. Wilksen, N. Arnold)

This working group will focus on tools and techniques for analyzing accelerator data from the FLASH DAQ. The emphasis will be on usage of the DAQ data rather than on detailed DAQ system implementation. Specific analysis use-cases will be developed ahead of time and then refined in collaboration with the other working groups. The group will explore implementation of these use-cases. Requirements for online and operations tools and offline analysis toolkits will be explored.

Working Group 2 Summary WG2_Summary_v2.doc

Working Group 3 Summary LOLB10_WG3_V3.doc

Working Group 4 Summary WG4_Report_v0_2.docx

Monday 22 February

09:00 → 10:30 Plenary I: Welcome and FLASH status

09:00 Welcome remarks

Speaker: Reinhard Brinkmann (DESY)

09:15 Status of long-bunch trains in FLASH

Speaker: Dr Nicholas Walker (DESY)

Slides walker-plenary-22-02-10_v2.pptx

10:00 Outlook for FLASH and FLASH 2

Speaker: Dr Siegfried Schreiber (DESY)

Slides 9mA-meeting-FLASH-schreiber.ppt

10:30 → 11:00 Coffee

11:00 → 12:00 Plenary II: FLASH as a test facility

11:00 ILC goals for FLASH

Speaker: Marc Ross (Fermilab)

Slides WLOLBT_100222_opening_mcr.pptx

11:20 XFEL goals for FLASH

Speaker: Dr Torsten Limberg (DESY)

Slides XFEL_goals_for_FLASH.ppt

11:40 FLASH photon users opportunities for long bunch trains

Speaker: Dr Josef Feldhaus (DESY)

Slides FLASH_User_Requirements.ppt

12:00 → 14:00 Lunch

14:00 → 15:50 Plenary III: September 9mA run

14:00 Data available from 9mA run (DAQ and analysis tools)

Speaker: Tim Wilksen (DESY)

Slides Data_available_from_9_mA_runs.pdf

14:15 Beam stability and beam loss issues

Speaker: John Carwardine (Argonne)

Slides Carwardine_analysis_22Feb10.pptx

14:35 LLRF 9mA operations and data analysis - I

Speaker: Dr Valeri Ayvazyan (DESY)

Slides LLRF_9mA_Operation.pdf LLRF_9mA_Operation.ppt

14:55 LLRF 9mA operations and data analysis - II

Speaker: Gustavo Cancelo (FNAL)

Slides LLRF_9mA_operations_and_data_analysis_-_II.pdf LLRF_9mA_operations_and_data_analysis_-_II.pptx

15:15 Dumpline instrumentation

Speaker: Dr Nicoleta Baboi (DESY)

Slides 2010.02.22_DumplineDiagnostics_FLASHoperationWS.ppt

15:35 Discussion

15:50 → 16:20 Coffee

16:20 → 17:40 Plenary IV: Working Group introductions

16:20 WG 1: FLASH setup, tuning & operations

Speakers: Dr Bart Faatz (HASYLAB), John Carwardine (Argonne)

16:30 WG 2: FLASH Feedback & Control

Speakers: Dr Holger Schlarb (DESY), Dr Valeri Ayvazyan (DESY)

Slides WG2_Intro.ppt

16:40 WG 3: ILC (9mA) Studies at FLASH

Speakers: Nikolay Solyak (Fermilab), Shinichiro Michizono (KEK)

Slides WG3intro.ppt

16:50 WG 4: DAQ & Controls

Speakers: Ned Arnold (Argonne), Tim Wilksen (DESY)

Slides WG4_Intro.ppt

17:00 Discussion

Tuesday 23 February

09:00 → 10:30 Working Group 1: Low-loss tuning experiences

slides WG1charge.pptx

09:00 Session introduction, WG goals

Speaker: Bart Faatz (DESY)

09:05 An operation model for rapid tuning and recovery

Speaker: John Carwardine (Argonne)

09:15 Low-loss tuning issues from 9mA studies

Speaker: Dr Nicholas Walker (DESY)

Slides walker-loss-tuning.pptx

09:35 Injector setup, tuning, matching experience with long bunch trains

Speaker: Siegfried Schreiber (DESY)

Slides 9mA-meeting-wg1-injector-schreiber.ppt

09:50 Discussion

09:00 → 10:30 Working Group 2: LLRF firmware/DOOCS servers

09:00 Summary of structure and functionality of SIMCON firmware and DOOCS

Speaker: Wojciech Jalmuzna (DESY)

Slides Wojciech.Jalmuzna.pdf

09:20 LLRF firmware upgrade for FLASH

Speaker: Waldemar Koprek (DESY)

Slides 9mAWorkshop.ppt

09:40 LLRF front-end server, FSM and beam pattern implementation

Speaker: Olaf Hensler (DESY)

Slides 9mA-Workshop-LLRF.pdf 9mA-Workshop-LLRF.ppt

10:00 Discussion

09:00 → 10:30 Working Group 3: HOM absorbers/rf input limitations

09:00 HOM absorber studies

Speaker: Jacek Sekutowicz (DESY)

Slides BLA-9ma-run-Workshop-2.ppt

09:20 Study of absorber effectiveness in ILC cavities

Speakers: Dr Chris Adolphsen (SLAC), Karl Bane (SLAC)

Slides Adolphsen_HOM_Absorber_Talk_at_DESY_02_22_10.ppt

09:40 Discussion

09:00 → 10:40 Working Group 4

09:00 Introduction to WG4 sessions: scope and goals

Speaker: Ned Arnold (Argonne)

09:10 Review DAQ Survey results: Presentation of results and brief discussion

Speakers: Ned Arnold (Argonne), Tim Wilksen (DESY)

Slides DAQ-Survey-Results.pdf

09:25 Experience with use cases using MATLAB

Speaker: Ned Arnold (Argonne)

09:40 Experience with use cases using SDDS

Speaker: Robert Soliday (ANL)

Slides DAQUseCasesWithSDDS.odp DAQUseCasesWithSDDS.ppt

09:55 Experience with use cases and FLASH DAQ tools

Speaker: Vladimir Rybnikov (DESY)

Slides FLASH_DAQ_experience.pdf

10:10 Discussion

10:40 → 11:00 Coffee

11:00 → 12:40 Working Group 1: Diagnostics, LLRF tuning

11:00 Session introduction

Speaker: Bart Faatz (DESY)

11:05 Single bunch diagnostics

Speaker: Christopher Gerth (DESY)

Slides FLASH9mA_gerth.ppt

11:20 Transverse diagnostics

Speaker: Dr Nicoleta Baboi (DESY)

Slides 2010.02.23_TransvDiag_FLASHoperationWS.ppt

11:35 Energy measurements in the bypass line

Speaker: Raimund Kammering (DESY)

Slides Bypass_energy_measurements.pptx

11:50 LLRF setup and tuning for long bunch trains

Speaker: Dr Valeri Ayvazyan (DESY)

Slides LLRF_setup_tuning.ppt

12:20 Discussion

11:00 → 12:45 Working Group 3

11:00 Latest results on beam loaded experiments at FLASH

Speakers: Chris Adolphsen (SLAC), Shilun Pei

Slides Adolphsen_FLASH_Sept_09_LLRF_Analysis.ppt

11:15 Results of high-gradient study

Speaker: Shinichiro Michizono (KEK)

Slides High_gradientWG3.pdf

11:30 High gradients with 9mA beam

Speaker: Julien Branlard (FNAL)

Slides Branlard_-_High_gradient_with_9mA_beam.pdf Branlard_-_High_gradient_with_9mA_beam.ppt

11:45 Discussion

11:00 → 12:40 Working Group 4

11:00 Continue talks on use case experience (if necessary)

11:20 Discussion and brainstorming usign survey and use case experiences focusing on a) Acquisition of data, b) Auto- or preprocessing of data and c) Tools or accessing and analyzing data

11:50 Option: Join LLRF setup and tuning talk of WG1

Speaker: Dr Valeri Ayvazyan (DESY)

Slides LLRF_setup_tuning.pdf

12:10 Discussion and brainstorming using survey and use case experiences focusing on a) Acquisition of Data, b) Auto- or preprocessing of data and c) Tools or accessing and analyzing data

11:00 → 12:10 Working group 2

11:00 LLRF high-level applications

Speaker: Zheqiao Geng (DESY)

Slides LLRF_High_Level_Applications.ppt

11:20 Stability of Master oscillator + frequency distribution systems

Speaker: Henning-Christof Weddig (DESY)

11:40 Discussion

12:40 → 14:00 Lunch

14:00 → 15:30 Working Group 1: Rapid machine setup and recovery

14:00 Session introduction

Speaker: John Carwardine (Argonne)

14:05 Optics, orbit, dispersion

Speaker: Eduard Prat (DESY)

Slides eprat_9ma.ppt

14:25 FLASH Save/Restore

Speaker: Pedro Castro (DESY)

Slides SR-Sequencer.pdf

14:40 Role of beam-based feedback in machine setup and recovery, eg ACC1 phase/amplitude

Speaker: Dr Christopher Gerth (DESY Hamburg, MPY)

Slides FLASH9mA_gerth_2.ppt

14:55 Discussion

14:00 → 15:30 Working Group 2+3: LLRF experience from 9mA studies

14:00 Piezo tuner experiences from the 9mA studies

Speaker: Mariusz Grecki (DESY)

Slides piezo_mg.pdf

14:15 Cavity resonance frequency measurement

Speaker: Waldemar Koprek (DESY)

Slides WK_CavTun_V2.pdf

14:30 High beam loading operation of 3rd harmonic module

Speaker: Dr Elmar Vogel (DESY)

Slides High_beam_loading_operation_of_3rd_harmonic_module_@_February_2010.pdf

14:45 Consideration on ILC cavity field gradient and the operational margin

Speaker: Akira Yamamoto (KEK)

Slides ILC-SCRF-Gradient-100223a.ppt

14:50 Discussion

14:00 → 15:30 Working Group 4

14:00 Join WG1 (Save/Restore talk and Behrens talk)

15:00 Brainstorming on online DAQ/data use cases - prepare joint WG1 + WG4 session

15:40 → 16:00 Coffee

16:00 → 18:00 Working Group 1+4: Rapid setup, online/offline data analysis

16:00 Session introduction

Speaker: Tim Wilksen (DESY)

Slides wg1and4-session-1DS.pdf

16:15 TINE archiver tool for online operations

Speaker: Mark Lomperski (DESY)

16:30 Online operations use-cases of DAQ

Speakers: Ned Arnold (Argonne), Tim Wilksen (DESY)

16:45 Offline data analysis use-cases of DAQ

Speakers: Ned Arnold (Argonnne National Laboratory), Tim Wilksen (DESY)

Paper Use_Cases.pdf

17:00 Discussion

16:00 → 18:20 Working Group 2+3 (WG3 agenda)

16:00 Study of stability requirements for ILC bunch compressor (best off-crest)

Speaker: Nikolay Solyak (Fermilab)

Slides RF_stability_off-crest_FLASH_Feb23_2010.pptx

16:15 Comparison between ILC spec. and FLASH 9mA study

Speaker: Brian Chase (FNAL)

Slides 9ma_Feb_workshop.ppt

16:30 Future works for long-pulse high beam loading demonstration

Speaker: Gustavo Cancelo (FNAL)

Slides LLRF_9mA_moving_forward_-_WG3.pdf LLRF_9mA_moving_forward_-_WG3.pptx

16:45 Discussion

19:00 → 22:00 Dinner in the DESY Bistro

Wednesday 24 February

09:00 → 10:30 WG 1: summary preparation

09:00 → 10:30 WG 2: summary preparation

09:00 → 10:30 WG 3: summary preparation

09:00 → 10:30 WG 4: summary preparation

10:30 → 11:00 Coffee

11:00 → 13:00 WG summaries

11:00 WG-1 summary

Speakers: Bart Faatz (DESY), John Carwardine (Argonne)

Slides WG1summary.pptx

11:20 WG-2 summary

Speakers: Dr Holger Schlarb (DESY), Dr Valeri Ayvazyan (DESY)

Slides WG2_Summary.ppt

11:40 WG-3 summary

Speakers: Nikolay Solyak (Fermilab), Shinichiro Michizono (KEK)

Slides WG3_2010LTBW_Summary.pptx

12:00 WG-4 summary

Speakers: Ned Arnold (Argonne), Tim Wilksen (DESY)

Slides WG4_Summary.ppt

12:20 Wrap-up (future plans)

Speaker: Dr Siegfried Schreiber (DESY)

Slides wrap-up-9mA-meeting-FLASH-schreiber.ppt

12:50 Closing remarks

13:00 → 13:05 End of Workshop