W. Hofle @ LHC Studies WG Day 2.09.2014 1 Review MDs Transverse Damper from Run1 to Run2 reported by W. Hofle for ADT & friends LHC MSWG Special Meeting

W. Hofle @ LHC Studies WG Day 2.09.2014

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Review MDs Transverse Damper from Run1 to Run2

reported by W. Hofle

for ADT & friends

LHC MSWG Special Meeting 02.09.2014

A. ButterworthG. KotzianT. LevensD. Valuch


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Overview Run 1: Three types of “Sessions”:• Commissioning• Operational Developments• Machine Developments

• Future ADT contributions to MDs dealt also elsewhere in today’s review:- Halo Cleaning (s. Redaelli)- Abort gap cleaning (AGC) and injection slot cleaning (J. Uythoven) - Quench Limits (B. Auchmann)- Instabilities (T. Pieloni)

Goals for ADT Team for 2015:• Re-commission features developed in Run 1 with new hardware and

software following the upgrade of ADT electronics• Contribute to diagnostics for instability observation• Develop new modes of operation and complete pending developments• Investigate noise properties of ADT


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LHC Transverse Feedback - Post LS1 Plan

Pickup Q7

Beam position module

Q7

Pickup Q9


Q9Analogue output to the power amplifiers

Digital signal processing unit

DAC

Gain control (CCC)

CLEANING

DAC

Pickup Qx


Qx

Pickup Qx


Qx

DACBeam transfer function meas.

Observation box

Tune/instability

diagnostics box

Fast b-by-b Instability

diagnostics

CCC, users, logging

• doubling # of pick-ups• complete re-cabling of PUs• new digital hardware• multiple ADCs and DACs• reduction of noise• flexibility for gain control• instability diagnostics (trigger !)• tune diagnostics (GPU)

Major upgrade in LS1(2013-2014)

D. Valuch et al. Evian 2014:https://indico.cern.ch/event/310353/session/4/contribution/14/material/paper/2.pdf

PickupQ10

PickupQ8

Production run of newdigital boardready for SPS Re-commissioning SPS now testbed

https://indico.cern.ch/event/310353/session/4/contribution/14/material/paper/2.pdf


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Past and Future MD Subjects / operational development

Run 1: • Abort Gap and Injection Gap Cleaning• Transverse blow-up with noise• Modulation of Gain for Tune Loop compatibility• Tune measurement from ADT with active excitation• Tune measurement from ADT with passive excitation• Variation of gain in ramp• Damper noise and emittance blow-up with colliding beams

Run 2: Subjects not completed and to be continued:• Improvements to Abort Gap Cleaning (bipolar pulse)• Tune Measurement• Tuning of 25 ns operation• Noise studies

Run 2: New subjects:• Halo Cleaning with coherent excitation Stefano• Improvements to Loss Maps (loss maps with full beam & energy) Stefano• New modes of operation (digital filters) to be tested on upgraded SPS damper first


Abort Gap Cleaning

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Abort Gap Cleaning by ADT (DDS) in V-plane stepping through a range of frequenciesInjection Gap Cleaning by ADT in H-plane New ADT development: bi-polar envelope for start-up New BSRT development: automatic switch on in coast

Tim

e (t

urns

)

Time (within turn)

3 ms

(Abort Gap Monitor (Synchrotron Light)

M. Meddahi et al. IPAC’10B. Goddard et al. IPAC’11E. Gianfelice-Wendt et al. IPAC’12

2009


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Selective Transverse Blow-up

stops at 18 mm apertureaperture measurement using blow-up

with transverse damper

Wire scanner measurements(normalized transverse emittance)

18 mm

2 mm

“White noise” i.e. pseudo-random numbers generated on FPGA clocked at 40 MS/s

• aperture measurements by blow-up• loss maps for collimation set-up• dynamic aperture• collimation quench tests (500+ kW)• knock out of bunches

any kind of excitation can be gated (also DDS produced narrow band)

gate, 11 ms (example)

IPAC’12 MOPWO050


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damper loss map 3rd order resonance

Comparison loss maps

Loss Maps:V. J. Moens, S. Redaelli et al. IPAC’13 MOPWO050

New development plan for 2015:making loss maps with gated excitation at end of fillwith full beam intensity at top energy and in ramp


Impact on Tune Measurement System (LHC)

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with damper, max gain used

• less broadening with lower gain• reduction of tune peak, i.e.

increase residual oscillations by more than 20 dB solution deployed in 2012: ADT gain modulation within turn and gated BBQ6 bunches are used for the Tune Measurement, these have low ADT gain

R. SteinhagenPAC’11, N.Y.

feedback gain


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ADT through the cycle - gain

Gain

Phase shift

Injection probe beam

Injection physics beam

Prepare ramp

RampSqueeze

Physics

Abort gapcleaning

Injection gap cleaning

Intensity

Energy

10's turns

100's turns

500's turns

Q injection

Q collisions

Inje

ctio

n

Inje

ctio

n

Inje

ctio

n

Inje

ctio

n

Inje

ctio

n

Inje

ctio

n

Adjust

Tune feedback

D. Valuch @ Evian 2011

LSA:0.25

LSA:0.02


evolution of beam oscillation amplitude Fast losses (BLM signal)

Fast Losses with ADT Simulating “UFO” Type Losses for Quench Test

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1 ms

IPAC’13 M. Sapinski et al. WEPME044 and THEA045(Fast Losses and Quench Tests)

Transverse Feedback was used as exciter in three quench testscarried out in February 2013


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Shaping Time Domain ResponseCondition for h(nTb) = 0 symmetry of roll off• Motivated by appearance of single

bunch instabilities

•Used operationally for squeezeand 25 ns spacing tests

• Causes additional blow-up follow-up

W. Hofle et al., IPAC’13 WEPME043


Performance with Bunch Trains in LHC 2012

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50 ns bunch spacingstandard + hold144 bunches (4x36)

25 ns bunch spacingenhanced bandwidth144 bunches (2x72)

Injection oscillationdamping

IPAC’13 W. Hofle et al., WEPME43


Bunch-by-Bunch cont’d – 25 ns

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shortest MD:two shots

August 26, 2011[in midst of 25 ns setting-up]

for 2015

G. Kotzian, ABP-HSC meeting 22.01.2014D. Valuch et al., Evian 2014

sensitivity to internal bunch motion

even

odd


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Tune Measurement from ADT data - active ADT excitation

2730 turns resolution too limited to clearly resolve peaks(20 Hz apart)

Repeat in 2015 - lower gain on leading 6 (12 bunches)- Longer acquisition buffers

F. Dubouchet et al. IBIC’13, TUPF29


Tune Measurement from ADT data- passive observation

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cleaning(injection)

high gain (@450 GeV)(trench @tune)

lower gain(average over 6 bunches)parasitic lines ! (ramp)

tune change at startof squeeze (0.280.31)(4 TeV)tune (H)

time

Based on recording of 6 bunches (horizontal plane)(also considering and tested excitation by short burst gated on 6 bunches)

F. Dubouchet et al. IBIC’13 TUPF29


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Proposal from 2012: ADT MD with noise and gain variationfor LHC MD block 2 / 2012

Motivation: Probe interplay of damper gain and noise for minimization of emittance blow-up

two ramps with8 bunches per beam at 1.5x1011

filling pattern with at least one bunch with• no collisions• collisions in IP1 and IP5• collisions in IP1, IP5 and IP8• collisions in IP8 only

With colliding beams at 4 TeV in adjust:

1st fill: different levels of noise with ADT at constant ADT gain measure blow-up and bunch-by-bunch lumi 2nd fill: based on results of previous fill inject a fixed level of noise with ADT and observe the effect of a change of gain on the lumi and the emittance

2012: Joint MD with BB team: not sufficient time to complete the program above 2015

V. Lebedev et al. IPAC’11, MOPO013


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Incoming Operational Development 2015

• Exploration of injection oscillation and instability diagnostics via Observation Box • Abort Gap Cleaning improvements (as needed)• Damping of Scrubbing Beam, optimization of 25 ns running (when scheduled)• Tune Measurement with ADT: active excitation of leading bunch train 1st priority• When stable ADT tune measurement tune loop using ADT can be envisaged • Tune measurement with observation box w/o excitation when operational• Efficient loss maps with full beam / during ramp and end of fill

• Halo Cleaning using Transverse Damper (S.R.)• Bench mark of blow-up equation with injected noise (W.H.)

Proposed (real) MDs for 2015

Summary

Documents

W. Hofle @ LHC Studies WG Day 2.09.2014 1 Review MDs Transverse Damper from Run1 to Run2 reported by W. Hofle for ADT & friends LHC MSWG Special Meeting