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Experience with Libera During PETRA III Commissioning at DESY

This presentation details the commissioning experience of the Libera BPM system during the PETRA III project at DESY. Key points include system setup, parameters like a circumference of 2304 m and an energy of 6 GeV, as well as the configuration of diagnostics including 228 BPMs, current monitors, and feedback systems. Critical issues addressed involve the integration of new technologies, latency reductions in data streams, and temperature stabilization methods adopted. The session aims to share insights gained from this process and highlight advancements in beam diagnostics to improve the efficiency and performance of the PETRA III light source.

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Experience with Libera During PETRA III Commissioning at DESY

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  1. Experience with Liberas during PETRA III commissioning Gero Kube, Igor Krouptchenkov, Frank Schmidt-Föhre DESY / MDI • Introduction • BPM System • Commissioning Experience • Critical Issues

  2. PETRA III @ DESY Parameters: • circumference:2304 m • energy: 6 GeV • emittance: 1 nmrad • emittance coupling : 1% (10 pmrad!) • current: 100 (200) mA • # bunches: 40 / 960 • straight sections: 9 • undulators: 14 • undulator length: 2, 5, 10 (20) m • supplement to X-FEL •  cost effective! Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  3. PETRA III @ DESY Damping Wiggler Sections new Experimental Hall PETRA III: Conversion of the former storage ring PETRA II into a light source C=2304m !!! Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  4. PETRA III Diagnostics • PETRA III: • 228 BPMs • → 226 for Orbit • → 227 Libera Brilliance • 6 Current Monitors • 2 Stripline-BPMs and • 2 Button-BPMs for • Multibunch Feedback • 1 Button-BPM for longi- • tudinal Feedback • 1 Wall Gap Monitor • 1 Laser-Wirescanner • 2 Beamlines for Emit- • tance Diagnostics • 3 Screens • Transfer Lines: • 20 BPMs • 10 Current Monitors • 4 Wall Gap Monitors • 11 Screens Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  5. Libera Brilliance for PETRA • → software release 1.82 BPM System • Overview Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  6. usual • DESY Console Console Server (TINE) CSPI Interface Server (Tango, EPICS,…) Server (Tango, EPICS,…) Server (Tango, EPICS,…) 1:1 1:N x CSPI Interface CSPI Interface CSPI Interface Libera Libera Libera Libera Libera Libera Pickup Pickup BPM System: Differences • Fast Data Stream (FOFB) • latency of standard FA data stream • → O(270 μsec) • new data output: Molex • → reduced latency O(130 μsec) • → in-house processing of raw data → not in use until now • Server Architecture Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  7. accelerator sections • different vacuum chamber cross-sections • → 8 different pickup types • large circumference N:2 • scattered infrastructure • → located in 8 „old“ experimental halls • and the new experimental hall NW: 2 NE: 2 EXP: 10 W: 2 E: 2 SE: 2 SW: 2 S: 2 number of racks in hall Accelerator Geometry: Implications • cable lengths (10 m … 200 m) • → 3 different cable types for loss compensation • (RFA 1/2´´-, 3/8 ´´-, 7/8´´-50) → 227 individual gain settings Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  8. OOArc OOStr NOOct UNEnt / UNExt DWRac DWOct UNCtd Pickup Types Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  9. UNExt DWRac OOArc UNCtd NOOct OOStr Pickup Types Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  10. Temperature Stabilization • old 7 octants • Liberas in temperature-stabilized hutches (together with feedback electronics) • → ± 1° C • new experimental hall • hall itself is temperature-stabilized • → ± 0.1° C Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  11. Read-Out Electronics • Electronic Racks Libera Brilliance Fiber Links (for FOFB) Signal-Combiner Libera Clock-Splitter Libera Brilliance Ethernet Switches (for Liberas) Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  12. Strategy • triggered data on demand (DD) acquisition (→ injection trigger) • observation of BPM sum signal • → fix gain setting (-55 dBm), but AGC works well • timing: adjust hardware trigger delay • → maximum of sum signal appears in same turn • → ADC signal in same channels • fine tuning via machine time (MT) phase delay • → optimize intensity of sum signal wrt. neighbour turns Beam Steering • Conditions • only one screen monitor behind injection • → beam steering depends on reliability of BPM system Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  13. BPM sum signal injection point • April 12: first turns • April 13: first stored beam • → single bunch, 20 μA (~ 109 particles) current monitor signal Beam Steering (2) • Milestones • April 3: first beam in PETRA • April 10: all magnet power supplies available Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  14. Result injection point not connected Libera Trigger Delays • individual adjustment • required for first turn (DD) measurements • adjusting via hardware trigger delay • → ADC signal from single bunch in samechannel • fine tuning via MT phase delay Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  15. tune settings integer part: SA acquisition fractional part: DD acquisition • adjustment of injection kicker strength • DD mode • → reduce • oscillation • amplitude Commissioning • correction of closed orbit • SA mode: AGC & DSC & switching on Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  16. Commissioning (2) • high level applications (examples) Dispersion (hor.) Dispersion (vert.) BBA ORM Tests Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  17. Beam Current Dependency • dependency on position readout • single bunch (→ real beam) • SA acquisition: • →DSC on, crossbar switching on • 100 samples for each bunch current • → mean and variance of pos. readout attenuator switching Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  18. offset tune: +400 Offset Tune • test measurement with „ideal“ beam • 40 bunches, I ≈ 16-20 mA • (with several re-injections) • AGC on • → Gain: -37…-39 dBm • SA acquisition: • →DSC on, crossbar switching on • compensation tune on/off • 500 samples for each offset tune • → mean and variance of pos. readout Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  19. Reliability: Fault Finding • monitoring of health parameters • resolution • ADC data • q-value Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  20. defect fan Fault Finding: Examples • defect bit on digital board Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  21. Faults • Libera fault statistics → Σ = 28 • further inconvenience • unstable synchronization wrt. system clock • problem of Libera or system clock? → under investigation Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

  22. Summary & Acknowledgment • description of PETRA III – BPM system • machine commissioning worked well & straight forward • → extensive use of TbT capability in combination with high precision in • SA mode • fine tuning of monitor resolution together with investigation of • resolution dependent influences recently started • unexpected high failure rate • → 28 out of 246 devices! • thanks • … to Kees Scheidt (ESRF) and Günther Rehm (Diamond) for fruitful discussions • and important hints concerning Libera functionality and commissioning experience. • … to Andrej Kosicek, Peter Leban, and Ales Bardorfer (I-Tech) for their support . Libera User Meeting, June 22, 2009 Gero Kube, DESY / MDI

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