injection and associated protection devices€¦ · injected beam: check stability of injection...
TRANSCRIPT
Injection and Associated Protection Devices
V.Kain, B.Goddard, W. Hofle, V.Mertens,
Protection DevicesS. Redaelli, J.Uythoven, J.Wenninger
V. Kain – eLTC – 5March08 1
Scope - ContentsScope:
– Stage A: limit 43 x 43, 156 x 156 with 9 x 1010 p+ per bunch
– Only commissioning steps which require set-up with beamOnly commissioning steps which require set up with beam
• Injection/SPS extraction interlocking not covered
– Commissioning steps are described for one beam
• other beam requires repetition of same steps
– Time estimate per step in general: 1 – 2 shifts maximum
– Not very specific yet about exact values of target parameters
Contents:I j ti i i i d i h A 1– Injection commissioning during phase A.1
– Injection commissioning during phase A.2-A.3
– Injection commissioning during phase A.4
V. Kain – eLTC – 5March08 2
– Injection commissioning during phase A.5
*target parameters need to be properly defined
Injection Region
TCDDKickerMKI
LEFT OF IP2 (H plane)
TCDITDI
MKI +90˚
MKISeptum
MSI
TCDI
TCLIBTCLIA
RIGHT OF IP2 (H plane)TCLIM
TCLIB
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V. Kain – eLTC – 5March08 4
Preparation Phase A.1, pilot intensity, OP/BT
Requirements:– Orthogonal steering available for MSI and MKI– Settings generated for TDI (out, coarse, protect) g g ( , , p )– Shot-by-shot logging configured– Timing tables verified (BI capture events)– Remove extraction permit at SPSp– Transfer line re-commissioned with beam
• With TED in, then TED moved out
– All TCDIs/TCLIs out– TDI masked (completely IN)– TCDD in point 2 IN– MKI ON, kick disabled
• Soft-start done– All screens in, downstream of TED
and downstream of MSI BTVSS: first screen in the LHC
V. Kain – eLTC – 5March08 5
• Cameras on
First Injections – MKI NOT pulsing Phase A.1, pilot intensity, OP/BT
Enable extraction permit
Injection (MKI disabled):Injection (MKI disabled):– Beam should arrive at TDI, off-center– Steer if required
• orthogonal steering at MSI and MKI already implemented in YASP• orthogonal steering at MSI and MKI already implemented in YASP– Check signals at screens and BPMs (BLMs no losses)
• BTVSS, BTVSI1, BTVSI2, BPTX, BPMW, BTVST (in front of TDI)Steer to have correct offset at TDI on screen– Steer to have correct offset at TDI on screen
• ~ + 30 mm
Verify BLM readings on TDI:Verify BLM readings on TDI:– Triggered acquisition of BLM readings
• Calibrate parasitically (mGy vs. intensity lost)
Th h ld h ld i
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– Thresholds should not trigger
Screen in front of TDI
First Injections – MKI pulsing Phase A.1, pilot intensity, OP/BT
Remove extraction permit – enable MKI, pulseEnable extraction permitInject
Adjust delay such that beam is in middle of waveform
Verify vertical position on BTVST in front of TDI
– Steer MKI angleBeware of BETS constraints– Beware of BETS constraints
Move TDI to PROTECT position– +/- 7 mm– Remove BIC mask on TDI
Start threading around ring…
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(Move out injection screens)
Circulating beam – 450 GeV initial commissioning (BI, beam dump,…)
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Injection re-steeringPhase A.2, pilot intensity, OP; Phase A.3, 3 x 1010, OP
Phase A.2: after establishing closed orbit:– Inject & circulate– Inject & circulate
– Initial optimisation of injection oscillations: re-steer injections
Phase A.3: high precision orbit measurements:– Inject & circulate
– Optimisation of injection oscillations: re-steer injections
• Minimise to… Δe < 0.5 σ (results in 12 % emittance growth without damping)
V. Kain – eLTC – 5March08 9*target parameters need to be properly defined
450 GeV optics measurements
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Injection stability - reproducibility Phase A.4, 3 x 1010, OP
Injected beam: check stability of injection point– Transfer line and MKI effects– Transfer line and MKI effects
– Inject & dump
– 1000 shots
U BPM d BTV i i j ti i BPM d BTV b f MSI i t f– Use BPMs and BTVs in injection region + BPMs and BTVs before MSI in transfer line
– Shot-by-shot, restarting after a couple of days (temperatures, MKI soft-start, …)
Circulating beam at injection– Orbit at injection point/TDI
– Beam sizes at injection point/TDI
– Looking at nominal cycle only…
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g y y
– Parasitically every time we fill
Aperture in injection region (1) Phase A.4, pilot intensity – 3 x 1010, OP/BT
Aperture bottlenecks in the LHC injection regions:– MSI, Q5, MKI, D2
– → Q5 tilted→ Q5 tilted• + 1 mm on IP side
• - 2 mm on IP side
IP2 (n1) IP8 (n1)IP2 (n1) IP8 (n1)
MSI ~ 5.5 ( 2 mm trajectory tol.)
~ 5.5 ( 2 mm trajectory tol.)
Q5 8.7 6.2
MKI 6 8/5 4 6 3/6 1
Injected non-kicked beam
MKI 6.8/5.4 6.3/6.1
D2 4.9/4.2 6.7/5.1 J. UythovenJ. Uythoven: InjWG 07-05
Q5 tight under nominal conditions – n1 = 6.2
MKI and D2 tight for – Non-kicked injected beam
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Non kicked injected beam
– Kicked circulating beam → beam in the injection kicker rise time gap (~ 0.9 μs)
Aperture in injection region (2) Phase A.4, 3 x 1010, OP/BT
Aperture measurement: MSI and Q5– Use injected beam → inject & dump, TDI out
• BLMs triggered acquisition modeBLMs triggered acquisition mode
• FBCTs in point 4/point 6
– Transfer line knobs in sigma to measure aperture
Li it d b t f MSI– Limited by aperture of MSI
– Calibrate BLMs at MSI (on TCDIM and MSIs)
Aperture measurement: MKI and D2– Use circulating beam → circulate & dump, TDI needs to be in PROTECT
– Kick circulating beam + scan bump at D2 or MKIKick circulating beam scan bump at D2 or MKI
• BLMs triggered acquisition mode
– (Take out bumps at the end)
V. Kain – eLTC – 5March08 13
Scan MKI waveform Phase A.4, 3 x 1010, BT/OP
Scan MKI waveform:– Inject & dump
– Use screen at TDI (90º downstream)Use screen at TDI (90 downstream)
– Scan kicker delay
Example: LHC extraction commissioning – SPS LSS6 – 2006a p e C e t act o co ss o g S S SS6 006kick delay was changed, position measured with screen.
V. Kain – eLTC – 5March08 14
Injection Matching (1) Phase A.4, 3 x 1010
Mismatch possibilities – leads to emittance growth and tail repopulation
Emittance growth:– Betatron dispersion mismatch – measurement of twiss parameters at injection point– Betatron, dispersion mismatch – measurement of twiss parameters at injection point
– Energy mismatch – verify with BPMs around the ring → see Jorg’s talk
– Geometry
Tail repopulation: verify with scraped beam from SPS and scrapers in the LHC → stage B
R lt f i l ti D i t ff t b t t d di i i t hResults from simulations: Dominant effect: betatron and dispersion mismatch
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Injection Matching (2)Phase A.4, 3 x 1010, OP/ABP
Oscillation of image on matching screen indicates mismatch– Matching screen in point 3 (will not be there for 2008)
LHC optics needs to be measuredTo measure twiss parameters at injection point (dispersion, betas and alfas)
– Matching screen turn-by-turnS i i j ti i– Screens in injection region
Eventually (= stage B) need to control better than: – Betatron mismatch: λ < 1.15 – Dispersion: maximum mismatch of 10 cm 0 001 radDispersion: maximum mismatch of 10 cm, 0.001 rad
Screen matching application:used for TI 2: • 2 D fit for beam sizes• optics calculated at any point in the
line• same application can be used for
LHC
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LHC
*target parameters need to be properly defined
Increasing intensity4 bunches max injected for 43 x 4316 bunches max injected for 156 x 156
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Operational States?In this phase injection protection starts to play a role
The systems will be commissioned for a certain envelopeThe systems will be commissioned for a certain envelope – Optics
– Emittance
Crossing /separation angle experimental magnet polarity– Crossing-/separation angle, experimental magnet polarity
– Maximum injected intensity
– …
What/who makes sure that the systems are not used outside these “operational states” without re-commissioning or adjusting?
V. Kain – eLTC – 5March08 18
Multi-bunch injectionPhase A.5, 4 x 3 x 1010 or 16 x 3 x 1010, OP/BT
Multi-bunch injection: – Adjust delay for MKI kick
For 16 x 3 x 1010: – Only after setting up the TDI
– For 4 x 3 x 1010: TDI roughly set upg y p
• Optics knowledge from phase A.4
• Centered
Example:
V. Kain – eLTC – 5March08 19
Example: LSS4/LSS6 extraction
Setting-up of TDIPhase A.5, 3 x 1010 – 4 x 3 x 1010, BT/collimation team/OP
The required setting of the moveable passive protection devices depends on the LHC aperture. Assume 7.5 σ.
TDI:TDI:– ~ 4m long, ~ 10 m upstream of D1, additional mask in front of
D1 (TCDD)– Protects machine against MKI failures
Required setting: 6 8 σ– Required setting: 6.8 σ
TDI – setting-up– At this stage independent of cleaning collimators– Setting-up like cleaning collimators: covered by Ralph’s talk
• Centering, alignment, beam size measurement
– Test of synchronized (automated) setting-up with the beam cleaning collimators– Verify fill-to-fill reproducibility, orbit feedback
Verify aperture for second beamVerify aperture for second beam Verify protection against MKI failure (3 x 1010):
– Trim the MKI angle (beware of BETS limits and critical settings)– Maximum escaping amplitudes must be < 7.5 σ and primary loss should only occur at the TDI
V. Kain – eLTC – 5March08 20
TCLIs → Stage B– Unless phase advance between TDI and MKI compromised
Setting-up of Transferline Collimators (TCDI)Phase A.5, 3 x 1010, BT/collimation team/OP
Requirement:– Transferline optics measured
Setting-up: each TCDI individually (the others need to be out)Setting up: each TCDI individually (the others need to be out)• Inject & dump
• Centering, alignment, beam size cross-check, set to 4.5 σ
• Use BLMs (local, non-local, BCTs TL/point 4/point 6)Use BLMs (local, non local, BCTs TL/point 4/point 6)
– Calibrate BLMs on TCDIs and masks parasitically• Thresholds set to: maximum allowed loss: 1 x 1011
• Verify response on nearby superconducting magnets 4.5 σ setting with maximumtoleranceVerify response on nearby superconducting magnets
Check phase space coverage: maximum amplitudes escaping system: < 6 σ• Inject & dump, move out TDI
• Use aperture scan knobs from transfer lines
tolerance
• Use aperture scan knobs from transfer lines – Oscillations down the line, generated by combinations of corrector magnets
V. Kain – eLTC – 5March08 21*target parameters needs to be properly defined
Setting-up transverse damperPhase A.5, 3 x 1010 – 4 x 3 x 1010, RF/OP
Details in Wolfgang’s talk
Commission transverse damper to damp injection oscillations:Commission transverse damper to damp injection oscillations:– Inject & circulate
– Could be done in phase A.4: single bunch: mis-steer injection
• Measure emittance in line and in ring after injection (with and without damping)• Measure emittance in line and in ring after injection (with and without damping)
– Multi-bunch: injection kicker waveform effect
• Verify with emittance measurement
Commission transverse damper to clean MKI rise time gap → stage B / depending on re-population mechanism and aperture in D2depending on re population mechanism and aperture in D2
– Might need to clean abort gap at the same time
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Injection protection needs to be revisited for…
New LHC optics version
Emittance changes
Injection re-steering– Aperture verifications in the injection region– Transfer line collimator centering needs to be verified– Injection protection needs to be set up again
P d ibili f liPoor reproducibility after re-cycling– Re-set up injection protection system
R t hi f t f liRematching of transfer lines– Transfer line collimators need to be set up again
Crossing- separation angle changes polarity changes of experimental magnets
V. Kain – eLTC – 5March08 23
Crossing , separation angle changes, polarity changes of experimental magnets– Injection re-steering
Conclusions
A commissioning plan has been developed to prepare the LHC injections for up to 156 x 156 with 9 x 1010 particles per bunch156 x 156 with 9 x 10 particles per bunch
Injection quality and injection protection has been taken into consideration
Details of target parameters still need definition
A “procedure/formalism/check list…” must be put in place to guarantee that the systems are not operated outside the parameters they have been commissioned forfor.
V. Kain – eLTC – 5March08 24