Collimator ControlsReadiness of collimators control from bottom to topState of automated collimator positioning

Extended LTCSession 6 - Readiness of ControlsFriday07March2008 14h302008/03/07 MJJ

Collimator Controls

Primary Actors (from bottom to top)Alessandro Masi, Mathieu Donze, Arnaud Brielmann, Jerome Lendaro, Roberto LositoJacky Brahy, Enrique Blanco VinuelaGuy Surback, Roland Chery, Nicolas Zaganidis Stefano Redaelli, Eric Veyrunes, Delphine JacquetSupport from LSA team, AB/CO-DM, M.Lamont

OutlineInstallation statusArchitecture evolutionFunctional StatusEnvironmental SurveyPositioning & SurveyApplication LayerAutomatic Collimator Positioning (Beam Based Optimisation)

Baseline Architecture (as decided in 2005)BLM system

Control room software:Management of settings (LSA)Preparation for rampAssistance in collimator tuningBased on standard LSA componentsDedicated graphical interface for collimator control and tuningOP responsibilityCollimator Supervisor System (CSS):Environmental Supervision through standard PVSS classSupport building, VME / FESAFesa Gateway to Control Room SoftwareSynchronization of movementsBeam Based Alignment primitivesTakes action on position errors (FB)Receives timing, send sync signals over fiber to low level (Ramp & Beam Based Alignment)Synchronization and communication (udp) with BLMCO responsibilityLow level control systems3 distinct systemsMotor drive PXI Position readout and survey PXI Environment Survey PLCATB responsibility & CO for EnvironmentOPCOCOATBATB

HW Installation statusToday some 75 Collimators are installed.== 92 by April !Details in talk of O.Aberle

HW Installation statusTemperature readoutAll PLCs in placeAll installed collimators connectedAll temperature gauges tested except in IP7Very few surprisesIP7: waiting for 220V power connections

HW Installation statusPXI installationAll PXI systems installedTest in progress: stagesPre-CommissioningTest signal connectivityNo motor movementAll done (IP7 finished yesterday)Commissioning 1Requires tunnel access for visual confirmation of mechanical movements, swichtches etc.IP5, IP6 in progress, followed by IP2, IP8, IP1 (constrained by tunnel access), then IP3, IP7.First LVDT-CalibrationCommissioning 2Remote testsIncluding PC-gateway & synch-signalLVDT-reCalibration, autoretraction, mechanical playFinished by last week of May

HW Installation statusCSS related hardwarePC Gateways installed in all points except BA7Fibers connectivity for synchronisation signals:Ready in IP1, IP2, IP3, IP6, IP7IP8, IP5 before end of March

Temperature monitoringBased on standard UNICOS / PVSS control environmentLogging DBPVSS ClientAlarm SystemPVSS ClientJapc ClientsJapc ClientsJapc ClientsJapc ClientsPLC programs automatically generated from excel files(excel files are extracted from Collimation Configuration tables in the DB with additional dump and alarm limits per temperature sensorCollimation ConfigurationPLC supervised by standard PVSS serverInternal store (Months of data)Feeds various clients (LoggingDb, Alarm, JapC, Configurable PVSS clients,)

Configurable PVSS clients

Temperature monitoring

Architecture EvolutionOnly considering Position control: 3 LayersFor various reasons (responsibility delimitation) the architecture grew more complex with 4 layers.A low level Fesa Server was introducedLonger Execution PathMore resources, more maintenanceDuplicated functionalityFor not much benefitAnd a complication for MCSLow Level Fesa Server taking more and more responsibility (calibration, expert access, )What is the solution ?Make Low Level Fesa Server to implement the same property interface as CSSSuggest to include also synchronisation control in the Low Level Fesa Server.

Low Level FesaCSS

Architecture (as evolved after 2007 runs)Machine TimingMachine Timing DistributionSynchronisationFan outATB kindly agreed to include the synchronisation control in the Low Level FesaLow Level Fesa Server became de facto the CSSCentral Collimator Application can (almost) talk directly to ATB CSS implementation as if it was the CO CSS implementationMany thanks to A.Masi for this 2007 Christmas present.

Position Readout and Survey

PXICollimator Supervisory System

(one or two per LHC point)ATB

Architecture (to be completed in 2008)Machine TimingMachine Timing DistributionSynchronisationFan outATB kindly agreed to include the synchronisation control in the Low Level FesaLow Level Fesa Server became de facto the CSSCentral Collimator Application can (almost) talk directly to ATB CSS implementation as if it was the CO CSS implementation

Missing functionalityCSS is now reporting asynchronously to requests. (i.e. more work for Stefano).Beam Based optimisation primitives not providedNeed an independent process that runs on the PC gateway

Position Readout and Survey

PXIBLM system

Beam Based Optimisation

(one or two per LHC point)Collimator Supervisory System

(one or two per LHC point)Optimisation Application

PXI and CSSAll functionality defined and ~implemented on PXI (except multi movement option for fast optimisation)Merge of Fesa Servers

Expert application for LVDT-CalibrationInteracts with Fesa Server to calibrateCalibration stored in MCSUpdates under control of RBACFesa device delivery toolTakes information fromCollimation Configuration DBPXI configuration DBFeed Fesa Configuration DB

RWA, LHC MAC 12/07*PXI: Tracking Jaw PositionsSettingReadingGenerally excellent resolution and performance.In the tunnel at some locations pickup noise.Being analyzed.S. Redaelli

PXI and CSSTo be finalized and testedFunction driven executionMachine protection functionalityWarning and Dump limitsMachine Protection limits (MCS) depending on EnergySynchronisationReception of Energy and other Machine ParametersInteraction with applications layer (trim and Sequencer)New functionality to be commisioned in April.Actual priority is HW commissioning in the tunnel.

Stefano has provided a lot of work in collaboration with Eric and DelphineDatabase Table definitions to store collimator configurationWEB interfaceCollimator configuration database populationCollimator Control ApplicationDefinition of parameter space to control collimators settings and limits.Adaptation of trim editor (with CO/AP) to visualize more conveniently the collimators following the Beam-IP-family hierarchy

Application Layer

*Collimation Configuration

Collimator Control Application

Collimator Parameter SpaceHigh level Trim parameter is expressed in Ns

Absolute values are obtained by folding in the beam based sbeam Xbeam

sbeam is obtained from Momentum, ebeam and bcoll.ebeam is the nominal emmittance for which the machine is protected. It is a collimator specific parameter. Measured e must be < ebeambcoll can be trimmed based on beam based alignment, to correct for local b-beating

Same hierachy for warning and dump limits.

Collimator Function Trim

Automated Collimator Positioning94 (up to 160 in final upgrade) collimators, to protect against machine damage and magnet quenches.The collimation process is a multi-staged process that require precise (0.1 beam) setting of the jaws with respect to the beam envelope. Goal for positioning accuracy is 20 m (0.1 beam at 7 TeV).Actual beam envelope (position and size) may change (from fill to fill ?, by how much?) Adapt to changing beam parameters to guarantee machine protection and to keep good cleaning efficiency

There are 376 degrees of freedom (4 motors per collimator) (188 if not considering the angle of the jaws)

30 seconds per degree of freedom (a very efficient operator) still requires about 3 hours.

We need automated tools and procedures

Beam ProbingBeam Loss MonitorBeam Loss MonitorTraditional method to establish the beam position, angle and size by touching the actual beam. (Required with new optics or after substantial changes of beam parameters)Starts with producing a well-defined cut-off in the beam distribution.Each collimator jaw is moved until the beam edge is touched. This step defines an absolute reference position for each jaw. (and angle if two motors are moved independently)Note: Best done from the last element in the cleaning insertion to the firstCollimators may stay in placeMachine is better protected against quenchesDisadvantages:Only possible with low intensity beam (i.e. 5 bunches, extrapolation from 5 to 3000 ??).Slow if done manually (188 positions )Delicate (e.g. moving a collimator too far changes the cut-off in the beam distribution).

Fast beam based setupBeam Loss MonitorBeam Loss MonitorComplements the traditional set-up method (possible with nominal beam intensity).Adjust positions to reproduce known beam loss pattern.Based on experience of other accelerators: Collimation efficiency is more closely related to beam loss patterns than to absolute collimator positions, which are sensitive to orbit deviations, beta beat, etc.Move jaws in hierarchical order into the beam halo up to the point where a specified beam loss level is recorded in the adjacent beam loss monitors.Fast if implemented as an automated procedure:Start at a fixed offset relative to a previously known position (only have to move short distances, no need to be retracted.Two beam can be tuned in parallel in the two cleaning insertions IR3 and IR7

Fast beam based setupProcedure in practice:The collimators are set at 1.5 retracted with respect to the last optimised value.The jaws are optimised one by one in a precise order.Optimization by moving in steps of 0.05 until the associated set of Beam Loss Monitors (BLM) detects a predefined value of beam loss. The BLM reference levels are found empirically and may be updated from fill to fill.

Timing implications:Starting position 1.5 , step size of 0.05 (50 m @ 450 GeV) 30 steps/motor 9600 steps in total (only position, no angles, final upgrade).Available time 5 min. two rings in parallel 60 ms per step (16 Hz)@ 2mm/s 50 m 25 ms per step needed for motor movement=> 35 ms for driving, data collection, reading BLM, deciding

Fast Optimisation PrimitivesCollimator Supervisory System (CSS)Send a trigger to adjacent BLM system on every motor movementBLM system sends a short transient data to the CSSOptimization primitive command (on CSS)Move until BLM-levelParametersMotors and step sizeBLM signals and limitsRepetition frequencyMaximum stepsExample:Move Jaw-left in steps of 10 um every 30 ms until BL signal reaches 103

This optimization primitive can be used by a central application forBeam ProbingFast beam based optimizationBeam Loss Monitor

The real chalengeLong tails after collimator movement,Large noise componentsIf these effect are also present in the LHC, optimisation will me more challenging.During the SPS MD, not able to make clean cut in the beam distributionBeam-dynamics: Re-poppulatution of tails over several 100th of ms.50, 150, 300, 450 &600 Hz noise

Fast Optimisation ImplementationTo be developed this year.Implement Multi-Step movements at Low LevelDevelopment of Optimiser ProcessBeam Based Optimisation PrimitiveAlready useful for operator assisted collimator setup.Development of Central Optimisation Control ProcessSequencing the optimisation of the individual jaw positionsDriven by a DB configuration, able to react intelligently if there is unexpected behaviour.Initially simple, improve by learning.Doctoral student ?The challengesConvince BI/SW that transfer of 600 bytes @ 30Hz is sustainable (when used occasionally for a single BLM crate at the time).Understanding the beam loss response

ConclusionsCollimation controls is ready to set the collimators for the first beam.

Still to be demonstratedFunction driven control.Machine protection functionality still to be tested.

Collimation position setup will be challenging.Development of tools and applications required

*****LHC-MAC 2007 06 15M.Jonker*From back to the front, first the tungsten jaws are moved in, then the secondary and finally the primaryOperationally more robust, to protect the cold aperture in the arcsOther techniques to repopulate the beam by blow up*While we optimise one beam in IR3, we can optimise the other beam in IR7*Change colors green on blue*Plot with LVDT reading (stop movement when becoming unsafe)Message: control system which is powerfullwe can remove reliableWe get fast BLM signalTools are available in the control system,Limits are in the understanding of the beam dynamicsTop level manula beam movement for beam probingTesting and implementation

Need good understanding of beam dynamics