Abort gap cleaning: status at 450 GeV and issues/plans at 3.5 TeV

W. Höfle, D. ValuchThanks to D. Jacquet, V. Kain et al.

Abort gap & Injection gap cleaning

• Cleaning mode – ADT excites the beam which then hits the collimators

• Excitation:

– in a defined time window (abort gap, next injection slot)

– by a synthesized signal (currently sinusoidal (various modulations available), noise is being studied)

Signals acquired during injection of the

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ADT performance

• Excitation amplitude currently at 10% of the available kick strength (scales with the damper electronic gain)

b=100 performance Optics 6.4 performance New Optics

Kick per turn in s Kick per turn in s @ b in m

ADTH beam 1 0.2 s 0.277 s at b=193 m 0.317 s 252 m

ADTH beam 2 0.2 s 0.273 s at b=187 m 0.253 s 160 m

ADTV beam 1 0.2 s 0.309 s at b=239 m 0.285 s 203 m

ADTV beam 2 0.2 s 0.316 s at b=250 m 0.386 s 305 m

LHC ADT performance in LHC optics version 6.5xxx compared to original assumptions (at 450 GeV/c), assuming 7.5 kV maximum kick voltage

ADT performance

Beam 2, Q9 vertical Abort Gap Cleaning tests 30. 4. 2010

slope: 0.0387 mm/turn @1/10 of strength(6 mm from turn 95 to 250)

Abort gap cleaning

• Abort gap cleaning sequence– Coherent excitation at QVER ± 0.01 in 15 steps (750 turns/step)

– Triggered by the 1000 ms timing

– Sequence stops automatically after 11240 turns

Abort gap cleaning

• Operation1. Sequencer sets the cleaning parameters for flat bottom. Drive all

non critical, check all critical.

2. Inject pilot

3. AGC activated by task enabling the timing before injecting first nominal

4. Injecting physics beam. Cleaning sequence is retriggered by timing every second

5. AGC deactivated in the sequence prepare for ramp by disabling the timing (+ setting key parameters to zero)

Injection gap cleaning

• Injection gap cleaning sequence– Cleaning bucket programmed on-the-fly by the injection sequencer

– Triggered by software (injection sequencer, could be protected by RBAC)

– Coherent excitation at QHOR ± 0.01 in 15 steps (750 turns/step)

– One sub-sequence is 11240 turns long

– Sub-sequence repeats up to 20 times

– Cleaning sequence redundantly stopped by two timings and software

Injection gap cleaning

• Operation1. Sequencer sets/checks the cleaning parameters

2. Inject pilot

3. After inj. the Injection sequencer checks the next injection bucket and programs the next cleaning bucket

4. Injection sequencer starts the cleaning as soon as the CBCM has accepted the injection request (typ. one SPS cycle)

5. Cleaning sequence is running

6. Cleaning is stopped 3 ms before the injection by Injection forewarning timing and redundantly 2 turns before injection by the BeamIn trigger

7. Cleaning stopped by the Injection sequencer after injection (even empty inj.)

8. Cleaning times out in hardware after 20 sequences (20 x 1s) had been played

9. Go to step 2

10. Sequencer disables cleaning by setting key parameters to zero at Prepare ramp

Cleaning sequence

• Abort gap cleaning sequence

11240 turns

15 steps (i.e. 750 turns/step)

Q ± 0.01

• Window function

Injection gap cleaning (hor. plane) Abort gap cleaning (ver. plane)

before 1st injection

1st injection

last injection

prepare ramp

before 2nd injection

Cleaningpulse

Sig

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Current status

• All cleaning settings are static:

– Set of regular LSA settings (frequency, exc. mode, amplitude etc.)

– Critical settings (Gating, Gating offset, Gating delay, Clean mode)

• Some settings will be different for 3.5 TeV operation

– Tune values

– Excitation mode, amplitude, cleaning sequence

– Window function (?)

• Critical settings are identical for injection and flat top

• Cleaning is not compatible with the tune measurement

To do…

• Delphine already created different users for AGC

– LHC.INJ_ADT (settings for injection)

– LHC.FT_ADT (settings for flat top)

• The actual parameter settings are not user dependent, this will be changed at next Technical stop

• The AGC control application needs to be updated

• The sequencer needs to be updated

To do…

• Agreement on the cleaning strategy at flat top with 70+ MJ in the machine

– When and how to start the cleaning

– What type of excitation to use

– Must avoid sudden high losses when we start to clean (beam dump)

Summary

• Abort gap / Injection gap cleaning routinely used at injection

• No technical issues to run the cleaning at flat top

• A set of multiplexed settings was already created to program the parameters for injection/flat top

• Need to agree on cleaning strategy at flat top

• Machine protection!

Abort gap & Injection gap cleaning

Time (turns)

start value(qStart)

stop value(qStop)

Start(Turn #1)

Stop(Turn #excLenTurns)

1 turn

increment infrequency fcFTWcalculated by FESA

Con

tinuo

us fr

eque

ncy

exci

tatio

n m

ode Frequency (norm.

to Q value)

Frequency (norm. to Q value)

Time (turns)

start value(qExc)

Start(Turn #1)

Stop(Turn #excLenTurns)Fi

xed

freq

uenc

y ex

cita

tion

mod

e

Parameter(e.g. fc (Hz))

Time (turns)

start value(qStart)

stop value(qStop)

Start(Turn #1)

Stop(Turn #excLenTurns)

Distance in turns(fcStepDist)

calculated by FESA

increment infrequency (fcFTW) calculated by FESA

1

2

3

4

5

6

Number of steps (numQSteps)

Step

ped

freq

uenc

y ex

cita

tion

mod

e

Cleaning sequence

Parameter(e.g. fc (Hz))

Time (turns)

Sta

rt (T

urn

#1)

Sto

p (T

urn

#exc

LenT

urns

)

Sing

le p

ulse

seq

uenc

e m

ode

Exci

tatio

n

Timing START

Parameter(e.g. fc (Hz))

Time (turns)

Mul

ti pu

lse

sequ

ence

mod

e

Exci

tatio

n #1

Timing START

Repeat sequence repCount times

Exci

tatio

n #2

Exci

tatio

n #r

epCo

unt

...

Parameter(e.g. fc (Hz))

Time (turns)Con

tinuo

us s

eque

nce

mod

e

Exci

tatio

n #1

Timing START

Repeat sequence till sequencestop timing is received

Exci

tatio

n #2

…

Exci

tatio

n #3

Exc

itatio

n fre

quen

cy/

ampl

itude

Time (turns)S

tart

(Tur

n #1

)

Sto

p (T

urn

#exc

LenT

urns

)

Star

t/Sto

p se

quen

ce b

y tim

ing

Exci

tatio

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Timing START(CTRV or soft)

Timing STOP(CTRV or soft)

Any running excitation will

stop here

Cleaning sequence

• Excitation within the turnK

ick

volta

ge

Time (turns)

Bun

ch #

1

Cle

anin

g in

the

abor

t gap

Abort gap (3 us)Excitation signalenvelope

AGC Excitation signal on the kicker

Bun

ch #

1

Bun

ch #

1

Bun

ch #

1

Gap delay (delay)

Kic

k vo

ltage

Bun

ch #

1

Inje

ctio

n cl

eani

ng

Cleaning window (up to 11.5 us)

Excitation signalenvelope

Excitation signal on the kicker

Bun

ch #

1

Bun

ch #

1

Bun

ch #

1

Gap delay (delay)

Time (turns)

Cleaning sequence

• Window functionK

ick

volta

ge

Time (turns)B

unch

#1

Abort gap (3 us) Excitation signalenvelope

Bun

ch #

1

Time (turns)AGC Excitation

signal on the kicker

Win

dow

fnc

Excitation signalenvelope

Multiplied by the window function

Exc

itatio

n am

plitu

de

(am

plitu

de)

ADT layout in the machine

IP4

beam 2

beam 1

Q7LQ9L Q9RQ7RH.M2.B2H.M1.B2V.M1.B2V.M2.B2

V.M2.B1V.M1.B1H.M1.B1H.M2.B1

beam 2

beam 1

SR4

[V]

[H]

[V]

[H]

[H]

[V]

[H]

[V]

Point 5Point 3 UX451

BPos Q9

BPos Q7

DSPU M1

DSPU M2

BPos Q9

BPos Q7

DSPU M1

DSPU M2

BPos Q9

BPos Q7

DSPU M1

DSPU M2

BPos Q9

BPos Q7

DSPU M1

DSPU M2

SR4

Bpos – Beam Position ModuleDSPU – Digital Signal Processing Unit