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Collimator Controls
• Readiness of collimators control – from bottom to top• State of automated collimator positioning
Extended LTCSession 6 - Readiness of Controls
Friday 07 March 2008 14h30
2008/03/07 MJJ
Collimator Controls
Primary Actors(from bottom – to top)– Alessandro Masi, Mathieu Donze, Arnaud Brielmann, Jerome Lendaro,
Roberto Losito
– Jacky Brahy, Enrique Blanco Vinuela
– Guy Surback, Roland Chery, Nicolas Zaganidis
– Stefano Redaelli, Eric Veyrunes, Delphine Jacquet
Support from LSA team, AB/CO-DM, M.Lamont
Outline
Installation statusArchitecture evolutionFunctional Status
• Environmental Survey• Positioning & Survey• Application Layer
Automatic Collimator Positioning (Beam Based Optimisation)
LHC tunnel
Underground, low radiation area
Surface support building
Control room
Baseline Architecture (as decided in 2005)
Collimator Supervisory System(one or two per LHC point)
Collimator Supervisory System(one or two per LHC point)
BLM system
Beam Permit
Central Collimation ApplicationCentral Collimation Application
Ethernet
Controls Network Data Base
Actual Machine Parameters
Data Base
Critical Settings
. . .
Machine Timing
Machine Timing Distribution
Synchronisation
Fan out
Control room software:• Management of settings (LSA)• Preparation for ramp• Assistance in collimator tuning
– Based on standard LSA components– Dedicated graphical interface for collimator control and
tuning– OP responsibility
Collimator Supervisor System (CSS):– Environmental Supervision through standard PVSS class– Support building, VME / FESA
• Fesa Gateway to Control Room Software• Synchronization of movements• Beam Based Alignment primitives• Takes action on position errors (FB)
– Receives timing, send sync signals over fiber to low level (Ramp & Beam Based Alignment)
– Synchronization and communication (udp) with BLM– CO responsibility
Low level control systems– 3 distinct systems
• Motor drive PXI • Position readout and survey PXI • Environment Survey PLC
– ATB responsibility & CO for Environment
Local Ethernet Segment
Motor Drive ControlMotor Drive Control
PXIPosition Readout and Survey
Position Readout and Survey
PXIEnvironment Survey
Environment Survey
PLC
OP
CO
COATBATB
HW Installation status
Today some 75 Collimators are installed.== 92 by April !Details in talk of O.Aberle
HW Installation status
Temperature readout– All PLC’s in place– All installed collimators
connected– All temperature gauges
tested except in IP7• Very few surprises• IP7: waiting for 220V
power connections
HW Installation statusPXI installation– All PXI systems installed– Test in progress: stages
• Pre-Commissioning– Test signal connectivity– No motor movement– All done (IP7 finished yesterday)
• Commissioning 1– Requires 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-Calibration
• Commissioning 2– Remote tests– Including PC-gateway & synch-signal– LVDT-reCalibration, autoretraction, mechanical play
– Finished by last week of May
HW Installation status
CSS related hardware– PC Gateways installed in all points except BA7– Fibers connectivity for synchronisation signals:
• Ready in IP1, IP2, IP3, IP6, IP7• IP8, IP5 before end of March
Temperature monitoringBased on standard UNICOS / PVSS control environment
PVSSServer
PLC PLC PLC
Logging DB
PVSS Client
Alarm System
PVSS Client
Japc ClientsJapc Clients
Japc ClientsJapc Clients
PLC 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 sensor
Collimation Configuration
PLC supervised by standard PVSS server• Internal store (Months of data)• Feeds various clients (LoggingDb, Alarm, JapC, Configurable PVSS clients,)
Configurable PVSS clients
Temperature monitoring
Collimator Supervisory System(one or two per LHC point)
Collimator Supervisory System(one or two per LHC point)
Beam Permit
Central Collimation ApplicationCentral Collimation Application
Ethernet
Controls Network Data Base
Actual Machine Parameters
Data Base
Critical SettingsMachine Timing
Machine Timing Distribution
Synchronisation
Fan out
Local Ethernet Segment
Motor Drive ControlMotor Drive Control
PXIPosition Readout and Survey
Position Readout and Survey
PXI
Collimator Supervisory System(one or two per LHC point)
Collimator Supervisory System(one or two per LHC point)
Beam Permit
Central Collimation ApplicationCentral Collimation Application
Ethernet
Controls Network Data Base
Actual Machine Parameters
Data Base
Critical SettingsMachine Timing
Machine Timing Distribution
Synchronisation
Fan out
Local Ethernet Segment
Motor Drive ControlMotor Drive Control
PXIPosition Readout and Survey
Position Readout and Survey
PXI
Low Level Fesa(one or two per LHC point)
Low Level Fesa(one or two per LHC point)
Architecture Evolution
Only considering Position control: 3 Layers
For various reasons (responsibility delimitation) the architecture grew more complex with 4 layers.
A low level Fesa Server was introduced• Longer Execution Path• More resources, more maintenance• Duplicated functionality• For not much benefit• And a complication for MCS
Low 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 CSS
Suggest to include also synchronisation control in the Low Level Fesa Server.
Low Level Fesa
CSS
Architecture (as evolved after 2007 runs)
Beam Permit
Central Collimation ApplicationCentral Collimation Application
Ethernet
Controls Network Data Base
Actual Machine Parameters
Data Base
Critical SettingsMachine Timing
Machine Timing Distribution
Synchronisation
Fan out
ATB kindly agreed to include the synchronisation control in the Low Level Fesa
Low Level Fesa Server became de facto the CSS
Central Collimator Application can (almost) talk directly to ATB CSS implementation as if it was the CO CSS implementation
Many thanks to A.Masi for this 2007 Christmas present.
Local Ethernet Segment
Motor Drive ControlMotor Drive Control
PXIPosition Readout and Survey
Position Readout and Survey
PXI
Collimator Supervisory System(one or two per LHC point)
Collimator Supervisory System(one or two per LHC point)
ATB
Architecture (to be completed in 2008)
Beam Permit
Central Collimation ApplicationCentral Collimation Application
Ethernet
Controls Network Data Base
Actual Machine Parameters
Data Base
Critical SettingsMachine Timing
Machine Timing Distribution
Synchronisation
Fan out
ATB kindly agreed to include the synchronisation control in the Low Level Fesa
Low Level Fesa Server became de facto the CSS
Central Collimator Application can (almost) talk directly to ATB CSS implementation as if it was the CO CSS implementation
Missing functionality
•CSS is now reporting asynchronously to requests. (i.e. more work for Stefano).
•Beam Based optimisation primitives not provided
Need an independent process that runs on the PC gatewayLocal Ethernet Segment
Motor Drive ControlMotor Drive Control
PXIPosition Readout and Survey
Position Readout and Survey
PXI
BLM system
Beam Based Optimisation(one or two per LHC point)
Beam Based Optimisation(one or two per LHC point)
Collimator Supervisory System(one or two per LHC point)
Collimator Supervisory System(one or two per LHC point)
Optimisation ApplicationOptimisation 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-Calibration• Interacts with Fesa Server to calibrate• Calibration stored in MCS• Updates under control of RBAC
Fesa device delivery tool• Takes information from
• Collimation Configuration DB• PXI configuration DB
• Feed Fesa Configuration DB
RWA, LHC MAC 12/07 15
PXI: Tracking Jaw PositionsSetting
Reading
50 m
20 s
20 s
50 m
Setting
Reading
10 m
20 s
Generally excellent resolution and
performance.
In the tunnel at some locations pickup noise.
Being analyzed.
S. Redaelli
PXI and CSS
To be finalized and tested• Function driven execution• Machine protection functionality
• Warning and Dump limits• Machine Protection limits (MCS) depending on Energy
• Synchronisation• Reception of Energy and other Machine Parameters• Interaction 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 Delphine
• Database Table definitions to store collimator configuration• WEB interface• Collimator configuration database population
• Collimator Control Application• Definition 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
18
Collimation Configuration
Collimator Control Application
Collimator Parameter SpaceHigh level Trim parameter is expressed in N
Absolute values are obtained by folding in the beam based beam
Xbeam
beamis obtained from Momentum,
beam and coll.
• beam is the nominal emmittance for which the machine is protected. It is a collimator specific parameter.
Measured must be < beam
• coll can be trimmed based on beam
based alignment, to correct for local 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
by Chiara Bracco
12 minutes for two positions
Beam Probing
Beam Loss Monitor Beam Loss Monitor
Traditional 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 first• Collimators may stay in place
• Machine is better protected against quenches
Disadvantages:• 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 setup
Beam Loss Monitor Beam Loss Monitor
Complements 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 σ 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 σ 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 σ, step size of 0.05 σ (50 μm @ 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 μm 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 movement
– BLM system sends a short “transient” data to the CSS
– Optimization primitive command (on CSS)
Move until BLM-levelParameters• Motors and step size• BLM signals and limits• Repetition frequency• Maximum steps
– Example: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 for– Beam Probing
– Fast beam based optimization
Collimator Supervisory System(one or two per LHC point)
Collimator Supervisory System(one or two per LHC point)
BLM system
Synchronisation
Fan outLocal Ethernet Segment
Motor Drive ControlMotor Drive Control
PXIPosition Readout and Survey
Position Readout and Survey
PXI
Beam Loss Monitor
The real chalengeMotor movement
10ms (20m)
Long tails after collimator movement,
Large noise components
If 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 distribution
Beam-dynamics: Re-poppulatution of tails over several 100th of ms.
Motor movement
50ms (25m)
(70 Hz)
50, 150, 300, 450 &
600 Hz noise
Loss tails with echo
12 sec
Fast Optimisation Implementation
To be developed this year.• Implement Multi-Step movements at Low Level• Development of Optimiser Process
− Beam Based Optimisation Primitive− Already useful for operator assisted collimator setup.
• Development of Central Optimisation Control Process− Sequencing the optimisation of the individual jaw positions− Driven by a DB configuration, able to react intelligently if there is
unexpected behaviour.− Initially simple, improve by learning.Doctoral student ?
The challenges• Convince 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
Conclusions
Collimation controls is ready to set the collimators for the first beam.
Still to be demonstrated• Function driven control.• Machine protection functionality still to be tested.
Collimation position setup will be challenging.• Development of tools and applications required
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