1/19/2005 Verena Kain, AB-CO 1

Safe Injection into the LHCV.Kain AB/CO

Contents and scope• The need for machine protection at injection• Interlocking – hardware and software• Passive protection systems – collimators• Protection level simulation results• Commissioning aspects• Conclusions

Input from B. Goddard, M. Lamont, J. Wenninger, H. Burkhardt

1/19/2005 Verena Kain, AB-CO 2

Machine Protection at Injection

Inside, damage visible over ~1m (melted steel)

8x1012p+ = ¼ of full batch

Holes in Cu : 450 GeV LHC p+ beam(from 2004 TT40 materials test)

5.3x1012p+ = 1/6 of full batch

• 2.4MJ in 450 GeV injected beam

• Damage limit around 100 J/cc~2x1012p+, ~5 % of injected batch

• 7.5 LHC aperture at 450GeV

• Tight aperture in transfer line (MSI ~7)

1/19/2005 Verena Kain, AB-CO 3

What can go wrong: magnet trips, kicker flashovers, wrong

settings…• Magnet trips can move trajectory by many in short

time (MSE: 40 in 1ms)• Kicker erratics, missings, timing etc.• Operator error• Corrupted settingsSlow failures:

– 10 in > 2-3ms: relying on interlocking

Fast failures:– 10 in < 2-3ms: interlocking + collimators

Ultra-fast failures: – 10 in few s: collimators

Magnet FamilyTime

constantTime for

1 ms ms

Family TI 2Extraction septum MSE 23 0.03Extraction septum MST 41 0.27Injection septum MSI 950 0.48Main dipoles MBI 773 0.11MBIAV1 2772 0.62MBB 1241 0.75MPLH 100 1.93MBIBH 1295 2.66MBIAV3 1959 3.69MBIAV2 2522 6.50

Family TI 8Extraction septum MSE 23 0.02Injection septum MSI 1100 0.69Main dipoles MBI 894 0.25MBIBV 1296 0.77MBHC 1010 0.91MPLH 100 1.28MCIBH 391 1.43MBIAH 2631 1.50MBHA 2607 1.58MBIAV 2453 5.84MCAIV(x3) 487 18.50

1/19/2005 Verena Kain, AB-CO 4

Machine Protection Strategy

• Avoidance: – Procedures to avoid dangerous situations

• e.g. never inject intensity above damage level into empty LHC (beam presence condition)

• Protection systems:– Active: surveillance + interlocks to inhibit

injection• Software – typical reaction time: ~seconds• Hardwired – typical reaction time:

– normal power converter surveillance (PCS): ≥2-3ms– (possible) fast current decay monitors (FCDM): ~ 1ms

– Passive: collimators for fast and ultra-fast faults• Collimators must be robust enough to withstand full

injected batch → low Z material (C, hBN).

1/19/2005 Verena Kain, AB-CO 5

Beam Presence condition

LHC beam permit

SPS beam “safe”

LHC beam presence

Injection permit

NO X X NOYES YES NO YES (low Intensity)YES NO NO NOYES X YES YES (high Intensity)

• Injection of beam above damage level only possible if beam already circulating in LHC (beam presence)

• Hardwired interlock !– SPS and LHC intensity must be monitored reliably

• Reliability and availability – 2 independent BCTs per machine/ring?

Protects against many of the failures in the LHC (trips, settings, …)

1/19/2005 Verena Kain, AB-CO 6

Hardwired Interlocks

SPS extraction kicker

LHC injection kicker

Movable TED beam dumps (stoppers)

+TBSE

TDI injection stopper + TCDDSPS LHCTransfer Line

SPS intensity LHC intensity

LHC energy

Injection permitExtraction permit

SPS beamSPS HWExtraction HW bumped BP MSE current, girder MKE bumper currentsSettings Transfer line HWFast beam losses

SPS Beam

InterlockController

LHC Beam

InterlockController

+SLP

Timing Timing

LHC beam permitLHC SettingsLHC HWInjection HWBTV screensTransfer line collimators

TED

pos

ition

TDI p

ositi

on

beam

Power Convertor Surveillance (PCS) and Fast Current Decay Monitoring (FCDM) are critical parts of the HW interlock system !

1/19/2005 Verena Kain, AB-CO 7

Software interlocks• Software interlocks

– Mostly used for less critical parameters and for redundancy:• beam quality, trajectory and losses in transfer

line, etc.– Much slower than hardware interlocks, not

failsafe…– Local reference values in front-ends for

equipment surveillance compared with central reference values • Reference values are machine mode dependent

1/19/2005 Verena Kain, AB-CO 8

Passive Protection for fast and ultra-fast failures

• Protection of LHC aperture and MSI aperture: – TCDI collimators for failures upstream of injection

regions– “generic” protection system with full phase coverage

• Dedicated collimators for kicker failures:– MKI (LHC) failure: TDI + TCLI are 90° downstream – MKE (SPS) failure: TPSG is 90° downstream

• No dedicated collimators for septum failures– Protection from MSE and MSI failures interlocking

1/19/2005 Verena Kain, AB-CO 9

TCDI Transfer Line Collimators

• Close to LHC and MSI (last 300m matching section of TLs)• Robust, based on TCS design (1.2m C jaw)• FLUKA model of 300m of TI 8 local shield for each TCDI

x’

x

0-60-120 degree collimators

60o120o

LHC apertureto protect at7.5

amax

6.9

• 3 collimators / plane (0-60-120°)• Setting: 4.5, tolerances: ≤1.4 • 2 motors/ jaw (angular control)• Protection level 6.9 (simulated

with Monte-Carlo including all imperfections: beat, mismatch from SPS, tolerances…)

6

1/19/2005 Verena Kain, AB-CO 10

TDI – TCDD - TCLI • Protects LHC (especially D1) against MKI failures• 90° downstream of the MKI. ~4m long hBN jaws• local protection of D1 with mask -> TCDD (1m, Cu)

• Auxiliary collimators TCLIs to complete system – For MKI-TDI phase advance ≠90°, and for flexibility (halo load…)– At nx180°±20° from TDI (1.2m long C jaws) – 1-2 years after LHC start-up

MKI

1/19/2005 Verena Kain, AB-CO 11

TDIMKI +90˚

TCDD

TCLIBTDI +340˚

TCLIATDI +200˚

KickerMKI

LEFT OF IP2

RIGHT OF IP2 TCLIM

TDI – TCDD - TCLI

TCT design, half jaw, low Ztwo beams in one pipe

TCS design, beams in separate pipes

1/19/2005 Verena Kain, AB-CO 12

Protection level simulations

• Extensive tracking simulations to check performance

• MKI flashover scanned with TDI, TCLI setting• Full Monte Carlo of single failures at injection

– All magnet and kicker families (SPS extraction, Transfer Line, LHC injection) for LSS4 - TI 8 – IR8

– Full TL + LHC injection region aperture model– All imperfections and errors included

Safe LHC injection losses on aperture below 5% damage limit during injection

1/19/2005 Verena Kain, AB-CO 13

MKI flashover simulations • TDI, TCLI setting of 6.8, to guarantee max. 5% above 7.5

• Increasing opening increases risk of damage

N/N0 of particles with amplitudes >7.5 y

1/19/2005 Verena Kain, AB-CO 14

Single failure tracking Monte Carlo results (1000 runs per

failure)Family Tolerable error

[k/k0]

required reaction time

[ms]

Covered by LHC TL

MPLH (LSS4 bumper) 0.185 201.0 TCDI PCSMKE (LSS4 kicker) 0.125 - TCDI -MSE (LSS4 septum) 0.005 0.1 TCDI -MBHC (TT40 H bend) 0.005 5.1 TCDI PCS / FCDMMBHA (TT40 H bend) 0.015 39.4 TCDI PCSMBI (main TI 8 bends) 0.003 2.7 TCDI FCDMMCIBH (start TI 8 H bend) 0.630 389.0 TCDI PCSMBIAH (end TI 8 H bend) 0.005 13.2 PCS PCSMBIBV (end TI 8 V bend) 0.003 39.5 PCS PCS3MCIAV (end TI 8 V bend) 0.225 124.0 PCS TCDIMSI (LHC injection septum) 0.003 3.0 FCDM n/a

• PCS = standard Power Convertor Surveillance (≥3ms)• FCDM = Fast Current Decay Monitor (~1ms), dedicated new system

1/19/2005 Verena Kain, AB-CO 15

Discussion of results• LHC protection looks OK, provided FCDM for MSI

– Detect and react to 0.3% change in 2.5ms• TL needs FCDM for MSE septum (reduce risk window), MBI

and MBHC– MKE and MSE faults can still cause damage to the TL… possible

solutions being studied• All other single failures are covered for TL & LHC

– TCDI system gives full protection from upstream failures

– Failures at end of line: slow enough for PCS and FCDM• More complicated scenarios not yet studied

– Grouped powering failures: e.g. general power cut– Combined failures

• Fault of machine protection system + other failure• e.g. wrong setting of passive absorber + trip of magnet family

1/19/2005 Verena Kain, AB-CO 16

Commissioning aspects

• Many parts can be commissioned without beam:– LHC injection BIC + matrices + data exchange;

collimator movements + interlocks; FCDM, PCS, logging, software, failsafe behavior, etc. etc.

• Beam is essential for commissioning of:– SPS & LHC safe beam and beam presence (BCTs)– TDI/TCLI/TCDI jaw alignment– Tests of full interlock system (EMC, …)

• Limited role of protection systems for early stage of LHC commissioning. (SPS extraction, SPS safe beam, TI 8 interlocks and LHC injection BIC needed !)

• Injection protection must be fully operational for injected intensity above damage level ≈ 15 bunches

17

Commissioning of TCDI system

• Setting up with beam: Transmission Measurement– Angular jaw alignment– Beam size measurement

• Use BCTs in SPS and downstream of TCDI (in LHC injection region - not in layout yet)

• Move TCDI jaws through beam, measuring transmission…– Required beam intensity ~1010 depending on BCT

resolution– Impact on LHC: ”inject – TDI dump” or “inject and

dump” mode

Setting up collimators:1) finding beam axis

2) align jaws with beam envelope

3) set jaws to required gap

1/19/2005 Verena Kain, AB-CO 18

TCDI setting up with beam - tests

0.00E+00

5.00E+09

1.00E+10

1.50E+10

2.00E+10

2.50E+10

3.00E+10

3.50E+10

4.00E+10

4.50E+10

5.00E+10

11/7/04 11:00 PM 11/7/04 11:30 PM 11/8/04 12:00 AM 11/8/04 12:30 AM 11/8/04 1:00 AM 11/8/04 1:30 AM 11/8/04 2:00 AM0

0.2

0.4

0.6

0.8

1

1.2L jaw -1.8mm R jaw -1.8mm R jaw -1.5mm

R ja

w -1

.2/-1

.5m

m

R ja

w -1

.5/-1

.2m

m

Jaw

s ou

t

L ja

w -1

.8 m

m

L ja

w -1

.5m

m

L ja

w -2

.1/1

.5m

m

L ja

w -1

.5/2

.1m

mFirst Results of transmission measurement for TCDI (TCS) setting up.

Simulated data

Measured transmissionvs. angular misalignment – looks promising

Methods tested in simulation with realistic parameters and tolerances

Attainable accuracy can be predicted – expect able to align to ~100rad.

Simulated transmission vs. angular misalignment:

1/19/2005 Verena Kain, AB-CO 19

Commissioning of TDI /TCLI

• Setting up TDI and TCLI with beam• Beam axis measurement : circulating pilot • Transmission Measurement for jaw alignment

– similar to TCDI– inject-dump required, intensity depending on BCT resolution

(max. ~1010)• Beam size measurement : circulating pilot (max. ~1010)

– jaw moved through beam– reconstitute transverse beam profile from surviving beam

intensity vs. position

1/19/2005 Verena Kain, AB-CO 20

Conclusions• Injection protection

– has to ensure only “safe” beam is injected into LHC during commissioning

– is absolutely mandatory if injected intensities exceed 2 1012 p+• LHC protected against many failures by “beam presence” condition• Comprehensive tracking simulations extensively used to define

protection systems and to determine protection levels– LHC fully protected with foreseen active and passive protection

• Require Fast Current Decay Monitor to measure 0.3% I in 2.5ms• Hardware and software interlocking is being specified → InjWG

– At present the protection systems cannot fully exclude TL damage– Simulations will be extended to grouped and combined failures

• Commissioning of the injection protection system is being prepared– Methods for setting up protection collimators being worked out