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FAIR Commissioning Phase A.1) - Injection and First Turn

Description

  • Commissioning of the last section of the preceding transfer line (matching section + few metres before) and the injection region
  • First commissioning of key beam instrumentation
  • Commissioning of the trajectory acquisition and correction
  • Threading the ring (first turn)
  • Closing the orbit to be ready for phase A.2 Circulating Pilot Beam

Entry Conditions

Entry Condition Special Entry Conditions
YR GS GE 1S CR HR
E.A.1.1 Full Dry-Run and operations check-out performed
E.A.1.2 Technical Services available
.01 Controls network
.02 Electrical network
.03 Cooling and ventilation
.04 Access and safety systems
E.A.1.3 Vacuum systems
.01 Insulating vacuum (where applicable: cryogenic equipment)
.02 Beam vacuum (machine)
.03 Beam vacuum (experiments)
E.A.1.4 Deliverables for the power circuits
.01 Cryogenics (where applicable) X
.02 Cryostat instrumentation (where applicable)
.03 Powering interlocks
.04 QPS and energy extraction
.05 Power converter currents checked
.06 Main lattice circuits (dipoles, quadrupoles) precycled to I_nominal, then powered to I_inj
.07 Correction circuits precycled to I_nominal, then powered to I_inj
.08 Experimental magnets & compensators OFF
E.A.1.5 High level controls
.01 All generic facilities (alarms, cryo, vacuum, ...) provided and tested
.02 Remote control of all equipment from MCR available and checked
.03 Key applications tested and available [note 1]
E.A.1.6 Timing systems
.01 Event distribution to all relevant equipment verified
.02 GMT signals (machine events, 1 Hz coarse timing clock, telegrams, UTC)
.03 Beam Synchronuous Timing (BuTis) signals to experiments and BI
.04 Timing tables available for "commission injection sequence"
.05 Distribution of safe beam parameters and flags (setup-beam-flag, beam-presence-flag, ...)
E.A.1.7 Machine protection subsystems (see detailed reference [#MachineProtection]
.01 FABS fully commissioned without beam to state "ready for pilot injection"
.02 distribution of safe beam parameters of preceding BPC segment fully commissioned
.03 HW setup-beam-flag intensity threshold set to < 2e10 ppb
.04 MCS commissioned for preceding BPC segment fully commissioned
E.A.1.8 Radiation monitoring systems
.01 RadMon Subsystem 1 commissioned (tbc.)
.02 RadMon Subsystem 2 commissioned (tbc.)
E.A.1.9 Pre-Injector and transfer lines
.01 HEST/HEBT commissioned up to last beam absorber/stopper before ring
.02 Transfer line collimators set OUT and verified
.03 last beam absorber/stopper movable and set IN for both transfer lines
E.A.1.10 Injection equipment
.01 Mangetic injection septum commissioned (actual-vs-reference function monitoring checked)
.02 Electro-static injection septum commissioned (actual-vs-reference function monitoring checked)
.03 Injection kicker/bumper pre-pulses commissioned (actual-vs-reference signal monitoring checked)
.04 Beam Injection Permit link to previous machine checked
E.A.1.11 Beam Instrumentation (link to details)
.01 Wire-Grids & beam screen: online display, grids/screens movable, timing, acquisition, applications
.02 DCCTs (ring): timing, calibration, acquisition, application
.03 ICT (TL): timing, calibration, acquisition, application
.04 BPMs: auto-triggering, timing, acquisition, application, (rough) intensity measurement mode
E.A.1.12 RF System
.01 All RF clocks and timing available, including injection kicker/bumper pre-pulse
.02 Low level synchronisation tested and available
E.A.1.13 Beam Dump System (link to details)
.01 Triggering via beam permit, timing system, FBAS signal tested (where applicable)
.02 Reliability run completed
.03 Post-mortem trigger/system tested
E.A.1.14 Collimation
.01 Low level collimator control available and tested
.02 all movable collimators set OUT and verified
E.A.1.15 Experiments
.01 Movable detectors (VELOs, roman pots, ...) OUT and locked OFF
.02 Machine-Experiment data exchange tested
.03 Beam abort (via interlock/timin, FBAS) and extraction interlock channels commissioned and tested

Notes on Entry Conditions

  1. Applications
  2. Beam Instrumentation
    • Wire Grids
      • item assumed to be commissioned before
      • item assumed to be commissioned before
    • DC Current Transformers
      • item assumed to be commissioned before
    • BPMs
      • item assumed to be commissioned before

  3. Machine Protection System
    • Interlock System
    • Fast Beam Abort System

Machine Setup

D efinition of optics, beam parameters, machine patter, and machine protection (MP) equipment that needs to be in place:
  • CRYRING
    • Machine Optics: ion optics -- reference to name in LSA
    • Beam Parameter: tbd.
    • Global Beam Pattern: tbd.
    • Machine Protection: not-applicable
  • SIS18
    • Machine Optics: ion optics -- reference to name in LSA
    • Beam Parameter:
      • preferred: easily available ions (Ar, U28+,...), intensity: 1e8...1e9 ppb, norm. emittance: xx umrad (e.g. single SIS18 turn, multiple SIS18 turns)
      • alternate: protons, 1e9...<1e10 ppb, norm. emittance
    • Global Beam Pattern:
      • high-duty/single cycle, low-duty/interleaved with other BPCs possible, ...
    • Machine Protection:
      • MP items that need to be in place (down-stream absorber blocks, etc.)
      • limits on how much parameters can be pushed (e.g. RP limits, ...)
  • ESR
    • Machine Optics: ion optics -- reference to name in LSA
    • Beam Parameter: tbd.
    • Global Beam Pattern: tbd.
    • Machine Protection: not-applicable
  • SIS100
    • Machine Optics: ion optics -- reference to name in LSA
    • Beam Parameter: tbd.
    • Global Beam Pattern: tbd.
    • Machine Protection: tbd.
  • CR
    • Machine Optics: ion optics -- reference to name in LSA
    • Beam Parameter: tbd.
    • Global Beam Pattern: tbd.
    • Machine Protection: tbd.
  • HESR
    • Machine Optics: ion optics -- reference to name in LSA
    • Beam Parameter: tbd.
    • Global Beam Pattern: tbd.
    • Machine Protection: not-applicable

Procedure

Step Activity Who Priority Special Procedures
YR GS GE 1S CR HR
A.1.1 Commission Injection Region (1 Pilot Bunch)
.01 Commission final metres of preceding TL 1 X
.02 Setup injection elements with beam 1
.03 Beam commissioning injection screens & grids 1
.04 Detailed steering onto moved-in injection collimator (if available -> otherwise vacuum chamber) 1
.05 Power injection kicker/bumper 1
.06 Check stability of transfer lines and trajectory without injection kicker/bumper 2
.07 Check stability of injected trajectory with injection kicker/bumper ON, measure kicker/bumper waveform 2
.08 Beam commissioning Software-Interlock-System (parasitic) 2
.09 Perform aperture scan at magnetic/electro-static injection septa 2
A.1.2 Threading Beam around the Ring
.01 Open injection absorber/collimator (if applicable, or not dumped onto vacuum chamber) 1
.02 Coarse beam commissioning of BPMs (asynch. acquisition/narrow band, if available) 1
.03 Commission trajectory acquisition and correction 1
.04 Threading around ring 1
.05 First measurement of energy mismatch (correction if needed) 1
.06 First BPM and corrector polarity checks and repairs 1
.07 Beam commissioning of DCCTs & ICT 1
.08 Commission BPM intensity measurement mode (parasitic) 2
.09 Systematic BPM and corrector polarity checks and repairs 2
.10 Systematic physical aperture scans, free oscillations and sliding bumps 2
.11 Systematic linear optics checks with kick/response 2
.12 Momentum aperture measurement 2
(N.B. priority definition 1: must, 2: optional, 3: nice to have, if time available -- 2&3: optional items, e.g. for night-time shift or if commissioning delayed by another item)

To be considered: required time - minimum (rough estimate, smallest time quantity 1h, otherwise given in terms of 8h shifts) required time - contingency (rough estimate, subjective at this time but should not reflect worst-case)

Details of activities

N.B. detailed 'cookbook': check list of individual steps (settings, gains, …):

Step A.1.1 Commissioning Injection Region

  • Injection Preparation (link to reference)
    1. check pre-injector intensity limit (should be < 1e10 ppb)
    2. check short- and long-term archiving databases are running (event & periodic triggered data available)
    3. check injection kicker/bumper settings (HV) and waveform
      • inhibit extraction of pre-injector
      • pulse injection kicker/bumper without beam (may need to temporarily override rule in timing master -> check MP issue)
      • verify synchronisation (digitised waveform traces(
      • verify injection kicker/bumper waveform (amplitude and synch)
    4. Move all wire-grids into beam
    5. Set wire-grid application into subscription mode
    6. Set inject-and-dump counter to 1000 turns (automated extraction timing, tbc.)
    7. Move last collimator/beam absorber before injection OUT
    8. Set ring BeamMode from 'No Beam' to 'Pilot'
  • Commission final meters in TL
    1. Close in-ring injection protection (if available)
    2. Power injection kicker/bumper ON, but kick disabled
    3. disable extraction kick in pre-injector
    4. Move last collimator/beam absorber before injection OUT
    5. Check all elements are pulsing/powered
    6. Enable injection kicker/bumper and extracts towards ring
    7. Check BPMs, BLM, wire-grids and screens
    8. Thread beam through the last part of the last part of the TL and injection septa
  • Beam injected into ring
    1. Final checks that all injection and BI systems are operational
    2. Thread beam through injection septa into ring – image beam on wire-grids/screen (if available/applicable)
    3. steer roughly through injection septa -- detailed setup later
    4. Thread through the first quads onto the first wire-grid monitor
  • Optional: Check stability of transfer lines and injected trajectory without injection kicker/bumper (should be done latest in A.x1)
    1. Check shot-by-shot archiving is working and all signals are correctly time stamped and correlated
    2. Run for ~1000 pilot injections without injection kicker/bumper, recording trajectory and screen shots
  • Optional: Check stability of injected trajectory with injection kicker/bumper on, and measure injection kicker/bumper waveform (should be done latest in A.x2)
    1. Check shot-by-shot logging is working and all signals are correctly time stamped and correlated
    2. Run for ~1000 pilot injections with injection kicker/bumper, recording trajectory and screen shots to check stability of injection kicker/bumper (pilot at same location at waveform)
    3. Check flatness/shape of injection kicker/bumper waveform (move pilot beam timing w.r.t. waveform)
  • Optional: Commission Software Interlock System (parasitic) (should be done latest in A.x3)
    1. Checks of beam-related acquisitions
    2. Test injection process with SIS active
  • Optional: Perform aperture scan at injection septa for injected beam
    1. Sliding bumps at septa in both planes, measure transmission (DCCTs) and/or losses (BLMs)
    2. Correct trajectory if not centred and re-measure
    3. Target: to-be-defined

Step A.1.2 Threading Beam around the Ring

  • First injections into ring with ring collimators out
    1. Beam off, move out collimators
    2. Beam on, first injection into ring past septa
  • Coarse beam commissioning of BPMs (asynch. acquisition/narrow band) and BLMs
    1. Check asynchronous/narrow-band acquisition working for first BPMs
    2. Check readback of BLMs, hopefully signals where beam is lost
  • Commission trajectory acquisition and correction
    1. Read-out of operational BPMs via threading application
    2. First steering in injection region
    3. Rough response checks for first correctors
    4. Test acquisition chain to shot-by-shot archiving
  • Threading around ring
    1. Use LEP/LHC strategy: correct over small range (manual BPM rejection) using few correctors
    2. Observe beam on wire-grid/screen (if/where available)
    3. Throughout:
      • Repair faulty BPMs only when into trouble – as long as beam keeps going round, continue
      • Kicks & polarity - first checks as needed
      • Systematic measurement program if we get stuck anywhere
      • Detection of poor BPMs:
        • look at orbit in normalised coordinates
        • compare predicted and achieved correction
        • use experience and/or use your brain
      • Detection of COD errors:
        • Compare predicted and achieved correction
        • Use few CODs per step
        • use experience and/or use your brain
  • First measurement of energy mismatch (correction if needed)
    1. Inject & measure using threading application
      • Accuracy of ~0.1% level should come for “free” from the dispersion trajectory
    2. What is correction threshold? 0.2-0.3%?
      • Probably most efficient to leave to later if possible and beam continues to go round
    3. Correct only if necessary
      • need to agree if to correct the integrated ring (Brho) or extraction/linac energy
  • First BPM and corrector polarity checks and repairs
    1. Some faulty elements will be found during threading
      • Results introduced in configuration file ‘online’ either in the threading/orbit steering application or in LSA
      • Eventually have to fix polarity errors – delay until opportune (first technical stop)
      • Disable faulty/bad BPMs if not needed
      • Repair only where essential (e.g. if crate down)
    2. Systematic checks can be made as needed during threading with kick-response and Loco analysis (lengthy as ~60 seconds per scan point)
      • Perform systematic scans using two correctors
      • get BPM polarity response, corrector polarity response, rough BPM calibration factor, rough corrector calibration factor
      • In general, for this analysis the iterative fitting needs experience…
  • Beam commissioning of DCCTs & ICTs
    1. Check acquisition and read-out
    2. Compare to pre-injector/last BCT readings, recalibration?
  • Commission BPM intensity measurement mode (parasitic)
    • BPMs are used as BCTs in this phase
    • Detailed commissioning will be done in Phase A.3
  • Optional: Systematic BPM and corrector polarity checks and repairs
    • see procedure in A.y1
  • Optional: Systematic physical aperture scans, free oscillations and sliding π bumps
    • checks transmission monitoring, loss sensitivity of BLMs (losses on injection septa ...)
    • see procedure in A.y2
  • Optional: Systematic linear optics checks with kick/response
    • Higher-order multipole polarity checks
    • see procedure in A.y3
  • Optional: Momentum aperture measurement
    • see procedure in A.y4

Problems

List of possible problems and first-order remedies:
  1. Cannot thread beam around – beam lost somewhere
    • Causes: physical aperture (e.g. RF fingers, unidentified lying object, …), misalignment, wrong transfer functions, wrong magnet settings, polarity errors
    • Diagnostic tools: BPM intensity mode, radiation survey stand-by, BLMs (if available/applicable), mobile BLMs and display, survey data, TF reference data, settings information
    • Remedies: Local steering, use smaller εn, update TF data, update settings, realignment, element replacement
    • Issues: Over-activation of components at problem location – cool-down times
  2. BPM errors render threading impossible
    • Causes: Polarity errors, calibration errors, cable inversions, electronic faults
    • Diagnostic tools: Analysis of steering data, systematic polarity/calibration scans, configuration data for connectivity
    • Remedies: Updated configuration, disable affected BPMs, repair
  3. Cannot close beam permit loop / spurious interlocks
    • Causes: Client cannot give beam permit on non-maskable input
    • Diagnostic tools: FBAS/Interlock supervision SW and equipment expert applications
    • Remedies: Change thresholds in case of remotely configurable levels, repair equipment, disconnect and reconfigure DB and retest affected BIC
    • Issues: If reconfigured, scope of tests to be remade after problem diagnosed, authorisation mechanism for interlock disabling
  4. Unstable injection after recycling, cannot reproduce machine
    • Causes: eddy currents, magnet model prediction inaccuracies
    • Diagnostic tools: trajectory analysis, beam loss measurement
    • Remedies: De-Gauss cycle, fixed pattern, longer waiting times/ring running on fixed (constant) injection energy , LSA model modifications, ...
  5. Polarity inversions or confusion of equipment
    • Causes: hardware errors, cabling errors, etc... arising in the control system databases

Exit conditions

clear definition of handover specs

List of systems to be considered “operational” afterwards

Exit Condition
Priority
O.A.1.1 Commissioning of the last section of the preceding transfer line and the injection 1
O.A.1.2 Trajectory acquisition and correction 1
O.A.1.3 Key beam instrumentation
.01 BPMs: acquisition, auto-triggered asynchronous (narrow-band) mode, first polarity checks 1
.02 ICTs (TL): acquisition, auto-triggered asynchronous mode, first rough cross-calibration 1
.03 DCCT (ring): acquisition, first rough cross-calibration with preceding ICTs 1
.04 Wire-grids and screens: acquisition, auto-triggered mode, first polarity checks 1
.05 BLMs: acquisition, first transmission/loss sensitivity measurements 2
O.A.1.4 Measurements
.01 Partial polarity and calibration error checks in correctors and BPMs 1
.02 Dedicated polarity and calibration error checks in correctors and BPMs 2
.03 Dedicated TL & injection region aperture checks 2
.04 Systematic kick/response optics measurements 2
.05 Energy mismatch between pre-injector and ring corrected to 0.1% 2
.06 Higher-order multipole polarity checked 2
O.A.1.5 Machine Protection
.01 Distribution of safe beam parameters and flags (setup-beam-flag, beam-presence-flag, ...) 1
.02 Injection/extraction permit generation and distribution checked with beam 1
O.A.1.6 Controls and Applications
.01 BI data acquisition, applications, displays and archiving 1
.02 Sequencer (mode transitions, beam requests, automatic collimator controls, ...) 1
.03 High-Level control applications: TransmissionMonitoring, BeamThreading, OrbitCorrection 1
.04 Shot-by-shot beam quality check for post mortem commissioned for injection 1
O.A.1.7 Injection Systems
.01 injection kicker/bumper operational with beam at nominal voltage 1
.02 injection kicker/bumper coarse timing and synchronisation 1
.03 Orthogonal steering of injection point across TL/ring interface 1
.04 injection region aperture measured 2
O.A.1.8 Magnets
.01 List of CODs that are found wrong (polarity and coarse calibration) 1
.02 main dipoles: injection settings/coarse energy matching with pre-injector 1/2
.03 main quadrupoles: major errors & polarities disturbing integer tune found and possibly corrected 1
.04 TL magnets, injection kicker/bumper, ring magnets: stability of injection after recyling magnets 2

Notes on Exit Conditions

  1. Applications
  2. Beam Instrumentation
    • Wire Grids
      • item assumed to be operational/working afterwards
      • item assumed to be operational/working afterwards
    • DC Current Transformers
      • item assumed to be operational/working afterwards
    • BPMs
      • item assumed to be operational/working afterwards
  3. Machine Protection System
    • Interlock System
    • Fast Beam Abort System
    • Generation & transmission of setup-beam-flag, beam-presence-flag, injection- and extraction-permit signals

Open Questions & Action Items

things that are not yet discussed, or integrated into the procedure

References

  1. "LHC Beam Commissioning Procedures", LHC Commissioning Working Group, 2003-2008, link to website
  2. FAIR Commissioning & Control WG Strategy & Concepts, Ralph J. Steinhagen, FC2WG #1 & #11, 20th May 2015 (minutes)

Acronyms

Abbreviation alt. English German
BPC BeamProductionChain Beam Production Chain
BPM Beam Position Monitor Strahllage Monitor, Positions Sonde
COD Closed Orbit Dipole (Steerer) Strahllage Korrektur Magnet
DCCT Direct Current (DC) - Curent Transformer

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