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