apollonio [email protected]
DESCRIPTION
ESS : Machine Protection considerations and BIS architecture. Apollonio [email protected]. Acknowledgments: D. Curry, A. Nordt , R. Schmidt. Outline. Introduction to ESS Linac4 Comparison ESS MPS and BIS Architecture Conclusions. Outline. Introduction to ESS - PowerPoint PPT PresentationTRANSCRIPT
ESS: Machine Protection considerations and BIS
architecture
Acknowledgments: D. Curry, A. Nordt, R. Schmidt
CERN
Andrea Apollonio page 2
Outline
• Introduction to ESS
• Linac4 Comparison
• ESS MPS and BIS Architecture
• Conclusions
CERN
Andrea Apollonio page 3
Outline
• Introduction to ESS
• Linac4 Comparison
• ESS MPS and BIS Architecture
• Conclusions
CERN
Andrea Apollonio page 4
Overview
● The European Spallation Source (ESS) will house the most powerful proton linac ever built. The average beam power will be 5 MW
which is five times greater than SNS. The peak beam power will be 125 MW
which is over seven times greater than SNS
● ESS is located in southern Sweden adjacent to MAX-IV (A 4th generation light source)
● To provide a world-class material research center for Europe Lund (Sweden)
[1]
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What is ESS?● ESS is a neutron spallation source for neutron scattering
measurements.● Neutron scattering offers a complementary view of matter
in comparison to other probes such as x-rays from synchrotron light sources.
The scattering cross section of many elements can be much larger for neutrons than for photons.
[1]
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Neutron Scattering● Neutron scattering can reveal the molecular and magnetic
structure and behavior of materials, such as: Structural biology and biotechnology, magnetism and superconductivity,
chemical and engineering materials, nanotechnology, complex fluids, and others
X-Ray Image
Neutron radiograph
Neutron radiograph of a flower corsage
Neutron scattering of hydrogen in a
metal organic framework
[1]
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What is Different About ESS?
● The average proton beam power will be 5 MW Average neutron flux is
proportional to average beam power
5 MW is five times greater than SNS beam power
● The total proton energy per pulse will be 360 kJ Beam brightness (neutrons
per pulse) is proportional to total proton energy per pulse
360 kJ is over 20 times greater than SNS total proton energy per pulse
[1]
= 62.5 mA * 2 GeV * 14 Hz * 2.86 ms
Average Linac
Current
Output Energy
Repetition Rate
Pulse Length
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Outline
• Introduction to ESS
• Linac4 Comparison
• ESS MPS and BIS Architecture
• Conclusions
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Linac4: Layout
CCDTL PIMSMEBTRFQH-Source DTLLEBT45keV 3MeV 50MeV 100MeV 160MeV
Transfer Line
RFQ DTL PiMS
Low Energy Beam Transfer
Radio-FrequencyQuadrupole
Medium Energy Beam Transfer
DriftTubeLinac
CoupledCellDriftTubeLinac
PiModeStructure
acceleration acceleration
Courtesy L. Hein
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Linac4 MPS: requirementsFocus of Linac4 MPS:• Availability: target >95%• Activation: above 10 MeV in case of beam losses [2]• Damage: very low risk of significant damage in case of ‘single
pulse losses’• Optimization of proton delivery to the different destinations
MPS requirements:• Highly dependable (almost same HW as LHC BIS)• Reaction time within the same pulse (<400us)• Allow for flexible operation (SIS + External Conditions)
MPS requirements during commissioning depend on:• Energy reached• Bunch intensity• Users availability
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LINAC4 BIS: Architecture
[3]
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BIS ACTIONS
‘SOURCE RF’ MASTER BIC:• Action on the Source
RF in order to inhibit the RF voltage
• For redundancy, action on the Pre-chopper in order to deflect the beam at 45 keV
‘CHOPPERS’ MASTER BIC:• Action on the Pre-
chopper at 45 keV• For redundancy,
action on the chopper at 3 MeV
• In addition, the PSB RF is disabled in case some beam still reaches the PSB
‘PSB EJECTION’ MASTER BIC• disable the
extraction kickers• magnet current
acquisitions at extraction time surveyed in addition via the SIS
To preserve the Linac4 Source stability, it is always better to act on the choppers to stop the beam, when possible
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Outline
• Introduction to ESS
• Linac4 Comparison
• ESS MPS and BIS Architecture
• Conclusions
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ESS: Layout and Parameters
Power of 5000 kW
Drift tube linac with
4 tanks
Low energy beam
transport
Medium energy beam
transport
Super-conducting cavities High energy beam transport
RFQ352.2 MHz
75 keV 3 MeV 78 MeV 200 MeV 628 MeV 2000 MeV
Source LEBT RFQ MEBT DTL Spokes High β
Medium β
HEBT & Upgrade
2.4 m 4.0 m 3.6 m 32.4 m 58.5 m 113.9 m xxx.0 m
352.21 MHz 704.42 MHz
DumpDogleg
Target
ESS Linac4
Proton beam energy
2.0 GeV 160 MeV
Pulse length 2.86 ms 400 usPulse repetition
rate14 Hz 1.1 Hz
Average beam power
5 MW 5.1 kW
Average beam current
62.5 mA 40 mA
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ESS: Target
Courtesy A. Nordt
Tungsten target with rotating wheel 33 sectors with cooling channels (Helium)Synchronized to 14 Hz
2mm gap
Wheel
He flow around slices
Angular sectors
Proton Beam Window
Target Monolithr=6m, h=10m
Beam Ports
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2 Weeks at ESS: MPS Activities• A risk analysis on a system basis had already been carried out• Several meetings per day with different system experts to
investigate possible failures and failure effects• Use of Jira + personal notes to keep trace of work progress• ‘Spread’ the idea of a Beam Interlock System• Define competences of MPS and responsibilities of User systems
Outcomes:• Failure modes and effects system by system• System dependencies• Identification of signals required for MPS (type and number)• Definition of Beam modes and Machine modes• Ideas for the commissioning phase• Definition of a suitable BIS architecture• Document on outcomes of the work
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Example: Warm Linac
Source Solenoids Steerers Quadrupoles BCTs BLMs BPMs Faraday Cups
Wire Scanners Absorbers Collimators Iris Choppers Vacuum Valves RF cavities
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Linac Interlocks and ActuatorsNo “LHC-type” beam dump (kickers + dump line)• The beam has to be stopped in the Linac at the lowest possible
energy by the actuators• Actuators are typically: Source and Choppers• No way to cut the portion of beam downstream the MEBT• Reaction time of the BIS has to be within the same pulse when a
failure occurs
Some peculiar Linac Interlocks:• BCMs current difference
Measures the transmission between two points Alternative to BLMs (only option at low energy)
• IRIS 8 blades, variable aperture to change beam current Complex device, cooling monitored
• BI moving devices (e.g. Faraday Cups): Position has to be interlocked
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ESS MPS: requirementsFocus of ESS MPS:• Availability: target 95%• Activation: above 10 MeV in case of beam losses• Damage: risk of significant damage in case of ‘single pulse losses’ even at low energy• Synchronization with the Target• ‘Errant Beams’ [4]
MPS requirements:• Highly dependable • Reaction time within: 10 us• Allow for operation up to different sections of the Linac
Actuators response times:• Source: 100 us• LEBT chopper: 100 ns• MEBT chopper: 10 ns
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ESS BIS: Architecture
ESS Source can be switched OFF without losing stability (always activated)
Cou
rtesy
A. N
ordt
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ESS BIS: Architecture
One more actuator could be represented by the RF of the RFQ (SNS)
Cou
rtesy
A. N
ordt
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ESS BIS: MASTER LEVEL 1
The Iris will be a critical component (design and interlock) Damage potential already in the LEBT (0.5 kW beam power) 1st beam destination: LEBT FC Input from Master Level 2 Input monitoring the effect of the chopper (ChON + current in BCM2 =
failure)
Ch 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 OUT
Interlock Element
SIS
Source Status
Iris status (cooling)
Solenoid 1 + Steerer 1 status
Solenoid 2 + Steerer 2 status
LEBT
Chopper statu
s
LEBT
Faraday Cup IN
LEBT
Faraday Cup OUT
EMU position?
Control Room Button
Radiation Monitors (PSS)
From Destination Master
LEBT Vacuum
TSS
Button
BCM2 +
Chopper
status
Master 1: Beam_Permi
t
1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 x 1
1 1 1 1 x 1 1 0 x 1 1 x 1 x x x 1
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ESS BIS: MASTER LEVEL 2
Monitors Beam destinations (FCs + Dump + Target) Current in the dogleg monitored and correlated with the beam destination Definition of destinations for the commissioning and test phases
Ch 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 OUT
Interlock
Element
MEBT OK
Farada
y Cup MEBT IN
Farada
y Cup MEBT OUT
DTL OK
Farada
y Cup DTL IN
Farada
y Cup DTL OUT
Spokes +
Mbeta1 OK
Farada
y Cup Mbeta 1 IN
Farada
y Cup MBeta 1
OUT
Mbeta 2
+ HBeta
OK
Current TARGET OK
Target Line
OK
Current DUMP OK
Dump Line
OK
Master 2: Bea
m_Permit
1 1 0 x x x x x x x x x x x x 1 Beam to MEBT FC 1 0 1 1 1 0 x x x x x x x x x 1 Beam to DTL FC 1 0 1 1 0 1 1 1 0 x x x x x x 1 Beam to MBeta FC 1 0 1 1 0 1 1 0 1 1 0 x 1 1 x 1 Beam to Dump
1 0 1 1 0 1 1 0 1 1 1 1 0 x x 1 Beam to Target
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ESS BIS: SLAVE MEBT
RFQ absorber and Chopper Dump: damage risk already at low energy BCMs current differences (transmission): main tool to detect losses at low
energy (below BLMs sensitivity) RF interlocks: 1 per RF cell Chopper: both User and Actuator
Ch 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 OUT
Interlock Element
SIS
RFQ absorber (cooling + secondary e
mission)
RFQ RF
RFQ trans
mission (BCM3-BCM2)
MEBT Chopper status
MEBT Collimators
status (cooling,
charge, position)
MEBT Chopper Dump
MEBT
Vacuum
BCM2 + Chopper status (from ti
ming)
BCM4 - BCM3
Slave 1: Beam_Permi
t
1 1 1 1 1 1 1 1 1 1 x x x x x x 1
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ESS BIS: SLAVE SPOKES + MBETA1
BLMs start to be in their sensitivity rangeCryo OK signal for start up (as LHC)Possiblility of fast losses due to power supplies failures of the
steerers
Ch 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 OUT
Interlock Element
SIS
RF OK (x #RF cells)
Spokes * MBeta
Vacuum
Steerers
BCMs
difference (tbd, BCM10 – BCM9?)
Cryo
OK (x
#Cryomodules)
BLMs
Slave 3: Beam_Permi
t
1 1 1 1 1 1 1 x x x x x x x x x 1
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Availability Model: IsographFailure rates and recovery times from the failure catalogue: ~99% availability
Work in progress: ESS Availability Model in Isograph
Benchmark for Linac4 Availability Model
Paper to IPAC’14 in collaboration with ESS
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Outline
• Introduction to ESS
• Linac4 Comparison
• ESS MPS and BIS Architecture
• Conclusions
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Conclusions
• A possible architecture for the ESS BIS was designed
• A document will soon be released summarizing these studies
• ESS availability model is under work (benchmark for Linac4 availability model)
Personal remarks:
• Previous experience with Linac4 was a fundamental starting point
• this very intensive way of working was very fruitful and allowed reaching an ambitious goal in a very short time
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THANKS A LOT FOR YOUR ATTENTION!
References:[1] slides 4-7: “The European Spallation Source”, D. McGinnis, PLC Workshop 2013.[2] “Predictions of induced radioactivity and residual dose rates in Linac4” F. P. Della Torre, M. Silari, EDMS 1304119 (2013)[3] “Beam Interlock specifications for Linac4, transfer lines and PS Booster with Linac4”, B. Mikulec et al. EDMS 1016233 (2013). [4] “Errant Beam Update”, Accelerator Advisory Committee, C. Peters, Accelerator Operations Machine Specialist, 7 May 2013
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Why is errant beam important● Errant beam mechanism
Beam hitting cavity surface desorbs gas or particulates creating an environment for arcing
● Super Conducting Linac (SCL) cavity performance degrades over timeSCL cavities do not trip with every errant beam pulse, but the probability
for a trip increases with timeCavity fields have been lowered and cavities have been turned off which
results in lower beam energy● SCL cavity performance degradation from errant beam can be
restored (except for cavity 06c)Requires cavity warm up during a long shutdown and then RF
conditioning before beginning beam operationCryomodules have been removed from the tunnel for cavity RF coupler
repairs but this takes months[3]
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SLAVE 2: DTLCh 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 OU
T
Interlock Element
SIS (BPM, BSM?)
RF OK (x #RF cells)
DTL Vacuum (fast valves?)
Steerers
BCM9 – BCM4
Standalone
BCM?
Slave 2:
Beam_Permit
1 1 1 1 1 1 x x x x x x x x x x 1
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SLAVE 3: Spokes + MBetaCh 0 1 2 3 4 5 6 7 8 9 10 11 1
213
14
15
OUT
Interlock Element
SIS
RF OK (x #RF cells)
Spokes * MBeta
Vacuum
Steerers
BCMs
difference (tbd, BCM10 – BCM9?)
Cryo
OK (x
#Cryomodules)
BLMs
Slave 3:
Beam_Permit
1 1 1 1 1 1 1 x x x x x x x x x 1
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SLAVE 4: Mbeta + HBetaCh 0 1 2 3 4 5 6 7 8 9 10 11 1
213
14
15
OUT
Interlock Element
SIS
RF OK (x #RF cells)
Mbeta * HBeta
Vacuum
Steerers
BCM11 – BCM10
Cryo
OK (x
#Cryomodules)
BLMs
Slave 4:
Beam_Permit
1 1 1 1 1 1 1 x x x x x x x x x 1
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SLAVE 5: Dump LineCh 0 1 2 3 4 5 6 7 8 9 10 11 1
213
14
15
OUT
Interlock Element
SIS
Dump status OK
BCMs
difference (before
and
after the
dogleg)
Magnets (Quads,
…)
Dump Line Vacuum (Fast
valves?)
BLMs
Slave 5:
Beam_Permit
1 1 1 1 1 1 x x x x x x x x x x 1
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SLAVE 6: Target LineCh 0 1 2 3 4 5 6 7 8 9 10 11 1
213
14
15
OUT
Interlock Element
SIS
Target status (slow)
Target (Rotating motor)
Magnets (Quads,
…)
BCMs
difference (before
and
after the
dogleg)
Target Line
Vacuum
(Fast valves?)
BLMs
Raster Magnet
Raster Beam instrumentation
Neutron Instrumentation
Collimator proton beam window
Slave 6:
Beam_Permit
1 1 1 1 1 1 1 1 1 1 1 x x x x x 1
• Collimators in front to proton beam window interlocked?• Rastering can be off for low intensity
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Example of Input Signal to the MISMagnet current surveillance:
Operational Mode
I(t)
0 A
100 ABeam to the target
Beam to the dump
Beam to the dump
Current Bend_DUMP = 0Current Bend_TARGET = 1
Current Bend_DUMP = 1Current Bend_TARGET = 0
Current Bend_DUMP = 0Current Bend_TARGET = 0