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Field Description of the LHCFiDeL - Status and Plan
Presented by L. Bottura
based on contributions of many
MARIC 28.02.2007
and LHCCWG 28.02.2007
Outline Objective of FiDeL Some details on the Field Model Interface to LSA (LHC control) Interface to off-line LHC model (through
WISE to MAD) Status and plan Milestones of validation
Objective and targets of FiDeL The Field Description of the LHC (FiDeL) aims at predicting
the magnetic state of any magnet, magnet assembly or magnet circuit in the LHC, following arbitrary operating cycles, to an agreed accuracy, as practical for accelerator control and beam dynamics studies
FiDeL clients: The high-level LHC control software (LSA), requires a
parameterization of transfer function and harmonics of the main magnet and corrector circuits to
Prepare machine settings for injection, define the ramp, and reach coast conditions
Provide trims for correction circuits during constant current plateaus, and especially to follow the field drift at injection
Provide trims for correction currents during the energy ramp, and especially during the snap-back at the beginning of the acceleration
The off-line LHC model (MAD), through WISE, requires a snap-shot of the deviations from nominal optics (field errors) in all magnets at an arbitrary time to perform studies on the LHC beams
Magnet normalization cycles to be defined in the operation and recovery procedures
An overall view and FiDeL scope
AB
TS-IC
AT-MASAT-MELAT-MTM
AT-MASAT-MTM
TS-SU
TS-SU
AB-OP
AT
AB-ABP
FiDeL scope
FiDeL field model concept Parametric model
Unified description of the field and field errors Cn applicable to all LHC magnets
Set of parametric equations for 7 physical components
Geometric (+ BS offset) Persistent Saturation Residual magnetization Decay Snap-back Ramp
Field parameters Adapt the parametric equations
to fit the measured or expected behaviours of the magnets
Set of ≈20 parameters, classified in 2 categories:
Shape parameters, equal for all magnets of the same type and family (e.g. all MB’s with inner cable 01B)
Amplitude parameters, specific to each magnet (e.g. geometric Cn)
Field Model
Phys.Rev. Special Topics, Accelerators and Beams, 9, 012402, 2006
Field model “components”
Seven components of different physical origin to describe the field and field errors
In addition: residual magnetization and ramp (not visible above)
The same model applies to single magnets and to string of magnets
Interface to LSA
Produce calibration functions (reproducible components)
Set ramp
Compute and correct dynamic errors in real-time (non-reproducible components)
Java implementation of FiDeL field model (AB-OP)
Field model parameters for all LHC circuits
(AT, AB-OP triggers import
of new configuration)
Feed-back from operation (AB-OP, AT consulted)
Oracle database of circuit parameters
(AB-OP)
Interface to MADSimulate LHC at the best of our knowledge of magnetic field and alignment
Quantify effect of systematic and random errors
Oracle database of magnet parameters,
included in the database of circuit
parameters (AB-OP)
magnet parameters (AT)
implementation of FiDeL field model substitutes present link to magnetic data extraction
Status Proposal of 1 year ago:
Mandate the FQWG to Complete the definition of the
project (interfaces, responsibilities, deliverables)
Compile above in a RDD to be agreed with AB-OP (LHC controls) and AB-ABP (MAD)
Propose participation of AT groups (MEL/MAS(*)/MTM are natural candidates)
Provide the structure for coordination and follow-up of progress
Spin-off the team that will be in charge of the LHC magnetics
We had 6 formal meetings (several informal) to:
Agree on an implementation proposal with participation from three groups in AT and AB-OP
Bond in a team the core of people concerned with and by the work
Define and pursue the data selection, sorting and re-analysis
Identify critical issues in the definition of the interfaces (configuration and cycle databases, sign conventions)(*) Now MCS
Project information
www.cern.ch/fidel
Scope of the workMinutes of meetingsMailing listDocumentation
Data repository (!)
Implementation plan
Task HR needed
(man-month)
Due Done
(%)
Model Specification 1 31/3/2007
Create FiDeL data structures 3 31/3/2007 ≈ 30
Implement FiDeL Engine 4 31/3/2007 test
30/9/2007 stable
Normalisation cycles 2 30/4/2007 ≈ 25
Magnetic data consolidation 20 30/6/2007 ≈ 50
MB/MQ/correctors powering and tracking test
6 30/6/2007
Sector powering test 3 6/2007 sector 78
9/2007 sector 45
Adapt WISE interface to FiDeL 2 30/9/2007
Magnetic data consolidation
Verify the validity of magnet acceptance data (i.e. ID cards)
Select from measurement databases the (additional) data necessary to the field model (e.g. current values between injection and flat-top)
Perform data reduction using uniform (standard) methods
Store results in a web-based repository
MB warm (AT-MCS) done, cold (AT-MTM) 90 %
MQ warm (AT-MCS) and cold (AT-MTM) done
MQM warm (AT-MEL+AT-MCS) done, cold (AT-MTM) in
progress MQY
warm (AT-MEL) and cold (AT-MTM) in progress MQTL
warm (AT-MEL) and cold (AT-MTM) in progress MQXA, MQXB
warm and cold data recovered (AT-MCS) for MQXA, to be done for MQXB
Correctors Warm (AT-MEL) and cold (AT-MTM) in progress
D1…D4 (TBD) NC magnets (TBD) Experimental magnets (TBD)
Issues for the coming 3 months Reference frames and conventions (beam direction vs.
measurement frame) Magnetic data
MQY warm (permeability correction, on-going) MQXB (inquiries sent, not clear what is and will be available) Normal-conducting magnets (data sources and formats are
very diverse) Experimental magnets (TBD)
Modeling Synthesis of magnetic data to the level relevant for modeling
(build integrals over series connected circuits) Implement semi-automated fitting procedures for massive data
treatment Verification of the quality and (if needed) adapt the parametric
model
Tracking tests in SM-18
What is the test ? Equip spare magnets (2 MB’s
+ 1 or 2 MQ’s) with existing field measurement instrumentation
Generate nominal (7 TeV) ramps in the main magnets and in the correctors using LSA and the FiDeL field model
Run the ramp and measure field and field errors
Diagnose result (B1 vs. specified ramp, B2/B1 tracking, b3 and b5 correction)
Where and when ? In the existing SM-18 test
benches (Jun 2007)
Why is it useful ? Detailed study of the
accuracy of the field model Test of the prediction
capability for different powering cycles
Difference among series tests and LHC, e.g. the issue of precycles at 50 A/s (series tests) vs. 10 A/s (LHC)
Effect of deviation from nominal operating conditions (e.g. waiting times)
Effectiveness of recovery procedures (yet to be defined)
Test LHC ramps during HC
What is the test ? Generate the nominal ramp in
all power circuits of a sector (commissioned) using LSA and the FiDeL field model
Run the ramp from CCC through LSA
Diagnose result (current and expected field tracking vs. specified ramp)
Where and when ? 7-8 (May-Jun 2007)
Maximum energy < 7 TeV 4-5 and/or 8-1 (Aug-Sep 2007)
7 TeV ramp+squeeze, RT trims
Why is it useful ? Proof of readiness for the
data structures and implementation
Early feed-back on ramp down-load and real-time trim mechanisms (LSA)
Verification of hardware limits, especially on corrector circuits (voltage swings) and quench protection hardware (voltage thresholds)
Scope of FiDeL discussion
AB
TS-IC
AT-MASAT-MELAT-MTM
AT-MASAT-MTM
TS-SU
TS-SU
AB-OP
AT
AB-ABPFiDeL scope
FiDeL range
A FiDeL project team ?
So far we have worked as an informal interdepartmental team, fostered by the FQWG
The resources required by this work are significant: A team of ≈ 10 people working part-time The estimate is ≈ 40 man-months for the work up to the main
deliverable, mainly in AT About 1/3 have been engaged to date Opinions are discordant as to the adequacy of the estimate The estimate does not consider adjustments and maintenance, which will be
a natural follow-up of the work The validation milestones have hardware implications, mainly in SM-18
This is a good time to have a formal assignment of the work-packages, and consolidate the framework of this
collaboration
Acknowledgements It is a pleasure to work with a motivated and
committed team: Laurent Deniau (secretary for the team), Mario Di
Castro, Per Hagen, Vittorio Remondino, David Sernelius, Nicholas Sammut, Stephane Sanfilippo, Ezio Todesco, Walter Venturini-Delsolaro
in collaboration with our colleagues in AB: Ilya Agapov, Massimo Giovannozzi, Mike Lamont,
Frank Schmidt, Marek Strzelczyk with the advice of some old wise men:
Jean-Pierre Koutchouk, Louis Walckiers, Rob Wolf