design and performance of the upgraded sps damper after ls1 g. kotzian for the damper team be-rf-fb,...

SPS Damper - Gerd Kotzian 1

Design and Performanceof the Upgraded

SPS Damper after LS1

G. Kotzian for the Damper Team

BE-RF-FB, 13. February 2015 MSWG

https://indico.cern.ch/event/367094/

13. Feb 2015

Acknowledgements: BE-RF-FB, BE-RF-CS, BE-RF-PM,BE-BI,BE-OP, BE-ABP,TN-EL




Transverse Damper in General

The transverse damper is a feedback system: it measures the bunch-by-bunch oscillations and damps them by fast electrostatic kickers.

Key elements: Beam position monitor(s)

Signal processing system

Power amplifiers

Electrostatic kickers

Key parameters: Feedback loop gain, phase,

and total loop delay

Kick strength

System bandwidth

2

BPM

BPM Signal Processing

andCorrection calculation

Kicker

Power Amplifier

Ideal equilibrium orbitBeam trajectory

BPM Beam position monitor

Tbeam

Tsignal

D.

Val

uch,

“T

RA

NS

VE

RS

E

FE

ED

BA

CK

: H

IGH

IN

TE

NS

ITY

O

PE

RA

TIO

N,

AB

OR

T

GA

P

CLE

AN

ING

, IN

JEC

TIO

N G

AP

CLE

AN

ING

AN

D L

ES

SO

NS

FO

R 2

012”

, in

LH

C B

eam

Ope

ratio

ns W

orks

hop,

Evi

an 2

011.

13. Feb 2015 SPS Damper - Gerd Kotzian


Outline

Objective:

Have a look at the upgraded SPS Damper and its internal structure,to gain insight in what/how the damper can be used e.g. for MDs.

Structure:

o Design of the upgraded SPS Damper

o 2014 Performance

o Outlook for 2015

13. Feb 2015

Damper, not Dumper


Former SPS Transverse Feedback System

o Last upgrade 1997-2000 in preparation of the SPS as LHC injector

o damping of injection errors and cure of resistive wall impedance driven coupled bunch instability (threshold ~5x1012 protons total intensity)

o operates since 2001 between lowest betatron frequency and 20 MHz (V & H plane) to damp all possible coupled bunch modes at 25 ns bunch spacing

o handles large injection errors of the order of several mm

o Tetrode amplifiers with two tubes drives kicker plates in push-pull configuration installed in tunnel under kicker, 200 W drive power per tetrode, 3 kHz to 20 MHz

o Technology of electronics of system used in SPS until 2012 dates from late 1990’s

13. Feb 2015


Scope and Motivation for SPS damper upgrade under LIU

Why LS1?

• sharing pick-ups with Orbit System (MOPOS) from Beam Instrumentation Group incompatible with MOPOS upgrade

• requirements for single bunch damping for protons used for LHC p-ion Physics (closer spaced proton bunches, 100 ns)

• ions injection damping with fixed frequency scheme, closer spaced batches

• individual bunch damping for crab cavity studies not possible with previous system (sampling was not synchronous with bunch in previous system)

• LHC doublet scrubbing beam incompatible with previous system

• controls with G64 chassis and MIL-1553 (a.k.a. MMI) became obsolete new controls for power system and LLRF, new RF function generators

13. Feb 2015

SPS Damper - Gerd Kotzian 613. Feb 2015

PU1BEAM

BPMProc.

PU2

BPMProc.

BPMProc.

BPMProc.

KICKER1

PLC1 PLC2200 WDriver

200 WDriver

FinalStage

FinalStage

Electrostatic PU processing

BW ~100MHz

Stripline pickupprocessing

pLHC,ScrubIons

pFT

Damper Signal

Selector

Damper Power System

KICKER2

BeamPos1

BeamPos2

DSPU1

DSPU2

ADC1

ADC2

DAC1

DAC2

BeamPos1

BeamPos2

DSPU1

DSPU2

ADC1

ADC2

DAC1

DAC2

BeamPos1

BeamPos2

DSPU1

DSPU2

ADC1

ADC2

DAC1

DAC2

BeamPos1

BeamPos2

DSPU1

DSPU2

ADC1

ADC2

DAC1

DAC2

SPS Damper LoopspLHC

SPS Damper LoopspFT

SPS Damper LoopsIons

SPS Damper LoopsScrub

from BBQ

from VNA from

VNABaseband Frontend(40 MHz)

RF Frontend200 MHz FSK

Baseband Frontend

RF Frontend200 MHz

Switch M1

Switch M2pLHC

pLHC

pFT

pFT

Ions

Ions

Scrub

Scrub

SURFACE BA2TUNNEL LSS2

cfv-

ba2-

alltr

dam

p[hv

]1cf

v-ba

2-al

ltrda

mp[

hv]2


PU1BEAM

BPMProc.

PU2

BPMProc.

BPMProc.

BPMProc.

Electrostatic PU processing

BW ~100MHz

Stripline pickupprocessing

Damper Signal

Selector

BeamPos1

BeamPos2

DSPU1

DSPU2

ADC1Baseband Frontend(40 MHz) ADC2

DAC1

DAC2

BeamPos1

BeamPos2

DSPU1

DSPU2

ADC1RF Frontend

200 MHz FSKADC2

DAC1

DAC2

BeamPos1

BeamPos2

DSPU1

DSPU2

ADC1Baseband Frontend

ADC2

DAC1

DAC2

BeamPos1

BeamPos2

DSPU1

DSPU2

ADC1RF Frontend

200 MHzADC2

DAC1

DAC2

from BBQ

Switch M1

Switch M2pLHC

pLHC

pFT

pFT

Ions

Ions

Scrub

Scrub

from VNA from

VNA

SURFACE BA2TUNNEL LSS2

pLHC,ScrubIons

pFT

KICKER1

PLC1 PLC2200 WDriver

200 WDriver

FinalStage

FinalStage

Damper Power System

KICKER2

SPS Damper LoopspLHC

SPS Damper LoopspFT

SPS Damper LoopsIons

SPS Damper LoopsScrub

cfv-

ba2-

alltr

dam

p[hv

]1cf

v-ba

2-al

ltrda

mp[

hv]2


Power System Consolidated

13. Feb 2015

Tetrode amplifier in SPS LSS2EM field simulation of kicker

new process control based on PLC in BA2

FESA remotely accessible


6x Beam Position Monitors installed in LS1

13. Feb 2015

BPCR.221• all BPMs re-cabled with 7/8-inch smooth wall

coaxial cables during LS1; [length ~250..700m]• BPH/BPV: electronics and amplifiers in the

tunnel tested and verified; "hot-spares" readily checked and kept in the tunnel

• BDH / BDV kickers unchanged

RF Faraday cage

SPS Transverse FB

• 2 BPCR (H/V) for LHC type beams (couplers maximum ZT @ 200 MHz)• 2 BPH electrostatic PU (pFT)• 2 BPV electrostatic PU (pFT)

Device Delay

BPH.202 2.48 μs

BPH.204 2.24 μs

BPV.205 2.12 μs

BPV.207 1.88 μs

Device Delay

BPCR.214 0.97 μs

BPCR.221 0.82 μs

H1/H2/V1 1.57 μs

V2 1.31 μs

Approximate transport delays:


Analog Frontend Control / External Controlo External control (only LHC type beams):

• disable 50 Ohm input termination

• disable attenuation

• enable amplifier

o Two analog frontend types: • RF frontend, used for pLHC and Ions,

LO = 200 MHz, I/Q components

• Baseband frontend (BB), used for pFT and Scrub, only I-component

o Input gain control:• RF: switching attenuators + amp, delay matched

dynamic range: -29 dB to + 10 dB.

• BB: variable gain amplifier (VGA)dynamic range: -27.4 dB to + 26 dB.

o Frontend protection circuitry• input overdrive protection: fast

• enables all attenuators, disables all amplifiers

• no recovery cycle is lost!

• reports as ALARM in LASER; action required!

o ADC overflows (8x)• report as WARNINGS in LASER

13. Feb 2015

I

Q

LO 400.8MHz

IN 2Delta

Constant delay step attenuator

Plus pre amplifier

8

I

QConstant delay step attenuator

Plus pre amplifier

8

Gaussian type low pass, fc~20-40MHz

Gaussian type low pass, fc~20-40MHz

ADC

CLK 40MHz (1)

17

ADC17

IN 1Sum

ADC

CLK 40MHz (2)

17

ADC17

LO 200 MHz

120 MHz

120 MHz

RF frontend schematicFEBbGainFERfGAINFESelect

in LSA


Beam Position Block (BeamPos)

o 2 BeamPos Blocks per damper loops module = one per pick-up input

o I/Q inputs of SUM and DELTA signals• in ADC sampling clock domain,

hence subject to delay adjustment

o CoRe – Conditioning and Resampling• I/Q phase rotation

• Down sampling: 120 MSPS 40 MSPS (25ns bunch sync)

o Clock domain crossing• from 2x ADC input clocks (delayed per pick-up)

to synchronous reference clock (undelayed)

o Normalization• position calculation (in-phase)

• “quadrature position” indicating head-tail activity

• bypass mode in case of DELTA processing (pFT)

o Overflows (Sum, Delta, Norm)• report as WARNINGS in LASER

13. Feb 2015

I

Q

S

IS

QS

D

ID

QD

Phase rotation to align the S and D vectors

I

Q

S

I’S

Q’S

AD

C s

atur

atio

n

D

I’DQ’D

fDS

DSSS

DSDS

SD

fcosnorm.pos22 QI

QQII

BeamPos1PpmCtrlBeamPos2PpmCtrlSwitchControl

in LSA

Sensitivity of LHC ADT to intra-bunch motion 12

0 1 2 3 4 5-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

Frequency / GHz

De

tect

ed

Am

plit

ud

e [N

orm

aliz

ed

]/ m

m

xN R (f

x)

xbar(fx)

Sensitivity of Frontend to intrabunch motion (LHC ADT)

22. Jan 2014

alternate processing scheme to detect and indicate anti-sym. oscillations:

indication of odd-mode oscillations!

re-evaluate for SPS case

0 0.5 1 1.5 2 2.5 3-0.2

0

0.2

0.4

0.6

0.8

1

1.2

Frequency / GHz

De

tect

ed

Am

plit

ud

e [N

orm

aliz

ed

]/ m

m

xN(f

x)

xbar(fx)

movement of centre-of-charges

normalized position as implemented in the BeamPos Block

Symmetric (even mode) Excitation Anti-symmetric (odd mode) Excitation

NB: although higher even modes visible the damper is acting only in baseband up to 20 MHz – for damping of higher frequencies wideband transverse feedback

13. Feb 2015 SPS Damper - Gerd Kotzian


Visualization of Bunch Motion

13. Feb 2015

Rapid identification of• quiet bunches• bunches with transverse center of mass motion• bunches with head tail motion• bunches with combination of center of mass and headtail motion with correlation

800 1000 1200 1400 1600 1800 2000 2200-1000

-800

-600

-400

-200

0BPOS-Q7-H-B2

Delta

Example:LHC run 2012

IDELTA

QD

ELT

A


DSPU – Digital Signal Processing Unit

o 2 DSPUs per damper; one per module; two inputs

o Signal processing• Notch filter

• Hilbert phase shifter / PU vector sum

• Bunch masking

• phase equalizer FIR (up to 64 taps), linearize phase of power system≈ low pass 1st order, cutoff freq. (-3dB) @ 4.5 MHzoperated at 40 MSPS better resolution at lower frequencies

• gain equalizer (up to 64 taps), digital low pass shaping output signaloperated at 120 MSPS

o Clock domain crossing• upsampling: 40 MSPS 120 MSPS

(Interpolated by gain equalizer = LP FIR)

• from synchronous reference clock (undelayed) to 2x DAC output clocks (delayed) implements actual 1-turn delay

o Switches• NotchEnable, PhaseShiftEna, Ch1/Ch2 enable,

Loop/Aux enable, Digital Loop Enable

o Overflows• report as WARNINGS in LASER

13. Feb 2015

phase equalizer FIR, comp. 1st order 4.5 MHz

digital low pass,fc ≈ 16 MHz

DSPU[1,2]EqControlDSPU[1,2]MaskDSPU[1,2]SwitchCtrl

in LSA:


DSPU – Digital Signal Processing Unit

13. Feb 2015

Functions (from RFFG)- in LSA:

Control signals (FESA) – in LSA:

Excitation input (DDS)

DSPU[1,2]EqControlDSPU[1,2]MaskDSPU[1,2]SwitchCtrl

FGCPpmControl

LoopsControlUse Digital Loop Switches preferred way to disable damper


Default Timings

o RT task (PPM READ/WRITE)

o 120 MHz resync (200 ms before INJ)

o fRev resync (flywheels in 5 clock domains)

o start function generation (RFFG)

o close damper loops H1/H2 resp. V1/V2 before injection

o scope trigger,

o VNA trigger,

o observation trigger + MEM readout task

o open damper loops

Loop Control:

o Use Digital Loop Switches (preferred way to disable damper)

o Loop ON & OFF timings are required to ensure proper behaviour do not disable

13. Feb 2015

LoopsControlin LSA:


Clock Distribution: fRF and fREV

o new fiber optic links between Faraday cage in BA3 and Damper racks in BA2• new fibers installed during LS1

• VME FO modules (RX/TX)

• status + diagnostics available (FESA)

o local clock distribution in BA2• active splitting (NIM modules)

o local clock generation• 120 MHz out of 200 MHz fRF

• beam synchronous, for sampling ADCs and DACs

• resync once per cycle to fREV before injection

o fREV resynchronization• 5 clock domains (SynClk, ADC1, ADC2, DAC1, DAC2)

• one flywheel per clock domain,

• resync once per cycle to fREV before injection

o Monitoring possibilities no Alarms (ion cycle does not transmit fRF all the time)

13. Feb 2015

expect over year20 degreesdrift @200MHz

1.9 km fiber links

long-term measurementWinter Summer

CLOCKControlCLOCKPpmControl

in LSA:


Closed loop delay compensation

o Thanks to Flywheels (generating fREV for each delayed clock) only fixed delay swing of 1 clock period () required (delay chip can do 10.24 ns)• modulo operator “wrapping” the delay around, i.e.

• ADC/DAC/Synclk tagging coarse delay, initial index for flywheels, stay in sync with fRF during ramp

o fixed delay and variable delay• fixed delay PPM, i.e. cycle dependent delays per beam type PU cable delays

− BPH/BPV for pFT beams− BPCRs for pLHC/Scrub/Ion beams

• fixed delay NON-MUXED, i.e. cycle independent delays− BDH/BDV delay same power system for all beam types− Fiber optic delay BA3-BA2

• variable delay PPM, varies throughout the cycle− ADC sampling delay (adjust during setting-up at flat bottom)− DAC fine delay (adjust with closed loop measurements)

o Delay compensation for momentum change, i.e. function(fREV)

o Including stable phase program

NB: to be automated in LSA using make rules.

13. Feb 2015

-5 0 5 10 15 20 253

4

5

6

7

8

9

10

11

12

Cycle Time / ms

Fin

e D

elay

/ n

s

DELAY PU1

DELAY PU2DELAY OUT1

DELAY OUT2


Functions Distribution

o 3 RFFGs: Horizontal / Vertical / eXperimental• 32bit Serial Control Link, 16bit payload (32bit optional)

• 1ms update rate (up to 16 kHz)

o 16 functions (PPM): gain, phase, PU mixing coeffs, delay• daisy-chained through all 4 damper modules via the backplane:

RFFG pFT pLHC Scrub Ions RFFG

• only 1 module active (ACK) at a time,

• frames return as NACK if no module is active

• tricky if 2 or more modules active at the same time (must be avoided)

• static value output vs. functions (LSA selectable)

o Frontpanel serial links (16bit)• 4x setpoint values to Power Converters

• send as hexadecimal numbers: 0x4300 == 4.3 kV

• voltages out of range will trip the power system EXPERT SETTING

• care must be taken when power cycling these crates: cfv-ba2-alltrdamph1, cfv-ba2-alltrdampv1,if in doubt set power system first to LEVEL1

13. Feb 2015

FGCPpmControlin LSA:

ALLRfFuncGen/ FPSLStaticValues

in LSA:

ALLRfFuncGen/ Functions

in LSA:


Damper Signal Selector (DSS)

o 2 DSS (H/V), with 2 fully independent channels, to select between inputs Module1 and Module2

o 4 + 1 + 1 + 1 loop inputs per output• 4 damper modules (pLHC, pFT, Ions, Scrub)

• 1 eXperimental module for developments and MDs (Xper)

• 1 transverse excitation input (BBQ Marek Gasior)

• 1 external VNA input

o selectable VNA output• allows for open loop TF measurements

• allows for closed loop TF measurements

• measure one plane, i.e. both modules and pick-ups with one VNA setup + remote controllable switching

13. Feb 2015

ALLDampSigSel/ SwitchPPMControl

in LSA:

Logbook: SPS [Thursday 09-Oct-2014 Night] 00:27

Damper commissioning and setting-up for LHC beam on MD1: parameters for all 4 dampers H1/H2/V1/V2 adjusted. Fine-delay for pick-ups 214 and 221 in H/V determined using the beam transfer function measurement. Input dynamic range adjusted based on +/-5mm bumps and nominal per bunch intensity (1.15e11 ppb, 48 bunches).

Today, for the very first time, the system was set-up completely remotely from the CCC.


Acquisition and Observation

o provide means to expert users/piquets for diagnostics• triggered by timing freezes acquisition buffers in all channels

• 7 Channels, (16 buffers)− 1 OBS channel (4 buffers, selectable sources)− 6 channels per clock domain (2 buffers each, dedicated)

o OBS data sources available• I/Q data for sum/delta inputs (per pick-up)

• position data (+head-tail component)

• probe various DSPU internal signals

• 40 MSPS, 4 buffers, each 2MSamples, or ~ 2000 turns

o Dedicated channels: 120 MSPS• 2 buffers per channel, each 4095 samples

• 1-turn data (2772 slices) per ADC and DAC channel

• adjustment of sampling delay

• clock tagging (bunch 0)

NB: constant data stream available (in the future) ObsBox! (LMC March 13th 2015)

13. Feb 2015

𝑓 𝑅𝐸𝑉=200 MHz

4620=

120 MHz2772

=40 MHz

924

BufferSettingBufferSelectOBSBufferAcquisition

in FESA3:

INJECTION DAMPING(damper, chromaticity)

approx. 1 ms


2014 Performance - pFT

13. Feb 2015

SUM

DELTA

[18.9.2014]

• Injection of fixed target proton beam

• Intensity about 10-20% of nominal

• more charges towards the end of the batch

• oscillating in HORIZONTAL


2014 Performance - pFT

13. Feb 2015

LEGEND:YELLOW delta signal pickup 202; BLUE kick voltage module 1; GREEN kick voltage module 2

Logbook: [Monday 27-Oct-2014, 23:15]

HORIZONTAL

VERTICAL

VNA HORIZONTAL 3MHZ

VNA VERTICAL 3MHZ

approx. 0.7 ms

1 ms

1 ms

RECOHERENCE

• open loop BTF measurement• sweep of two betatron lines• adjustments using phase setting and loop delay• synchrotron sidebands seen


LHC25ns beam as seen by pFT

13. Feb 2015

[18.9.2014]

• Injected batch of 12 LHC bunches,

• spaced by 25ns,

• intensity about 1.1x1011 ppb. Saturation phenomena develops 10 turns after the injection.

[19.9.2014]The effect comes from an electron cloud and the amplifiers handle it with no problems. It runs like this since 2008.

SUM

DELTA


2014 Performance - pLHC

13. Feb 2015

Logbook: SPS [Thursday 09-Oct-2014 Night] 00:27

HORIZONTAL

VERTICAL

DAMPER OFF

DAMPER OFF

DAMPER ON

DAMPER ON


LHC Pilot Setting Up: Open Loop BPCR.214.V

13. Feb 2015

o OL-Ver 100 kHZ o OL-Ver 1 MHZ o OL-Ver 2 MHZ

o OL-Ver 4 MHZ o OL-Ver 6 MHZ o OL-Ver 10 MHZ

[07.12.2014] 18:49 19:35 5-10 min/measurement OPTIMIZE … ?


pLHC.MD3 - Observations

13. Feb 2015

• Data during MD3 cycle (25ns, no splitting)• Recorded: 4th injection (@ 10800 ms)


~70 turns

1 turn

1st batch 2st batch 3rd batch 4th batch

activity in the last injected batch(+1st order roll-off of damper gain)


Status End 2014

o Completely new system built and taken into operation (March – Dec)

o Commissioning challenges:• Issue with pFT isolation transformers of all

PU inputs had polarity swapped

• FESA3 class on-the-fly bug-fixing

• at the time no high-level software … all setting-up done in FESA

• All sorts of troubles with the internal observation system …

“… driving your car with windows painted black – you have to get off to see if your lights are on!”

• Setting up of feedback parameters requires stable beam conditions (here I’m not referring to “stable beam”); [tune, chromaticity, injection timing, bucket selection, … ]

• Damper switched OFF by CCC while we were setting up things in BA2 …?!! … communication issue

13. Feb 2015


Outlook for 2015 – SCRUBBING

o Evaluate scrubbing module Investigate on “phase behaviour”

• compare Scrub vs. pLHC

• sharing same PU and same power system, expect same behaviour …

o Move to full I/Q signal processing

• currently the scrubbing module is too sensitive to sampling delay

• implement in analog, requires modification of HW

• DDC - digital down conversion, modification of FW

o run Scrub + pLHC damper in parallel

• Scrub active during splitting process (40 MHz present)

• pLHC kicks in once splitting is complete (200 MHz restored)

13. Feb 2015

“PU signal”

single bunch doublet

200 MHz BP filtered

40 MHz BP filtered(120 MHz sampled)

Analog signals before digitization:25 ns spaced doublets (during LAB testing)


Outlook for 2015 – USER INTERFACE

o refactoring damper loops FESA class V2.0• firmware: excess functionality removed (mainly housekeeping, no change in signal

processing!)

• testing using the Xperimental crate, no impact on operations (yet)

o make LSA consistent with new FESA class• adding value generators, for cycle generation definition of “safe settings”

• value generation for timing knobs

• declare make rules for functions, in particular delay/gain

o GUI in JAVA• talks to LSA (set parameters) and FESA (read back)

• loads settings to LSA for 1 active damper (sets others to “safe settings”)

• configure ACQ and fetch OBS data from FESA

• display status and monitoring (frequencies, voltages, and power levels)

• trimming of feedback parameters (in LSA, with history)

• store/recall reference settings

• import/export damper settings to file (consistent snapshot, e.g. for/during MDs)

13. Feb 2015

“RESTORE TO DEFAULT SETTINGS”Kick-off meeting: 18.Feb 2015, 1430 in the CCC


Outlook for 2015 - AOBs

o OASIS signals• route essential signals to remote samplers

o Logging• Have damper parameters also stored in the MDB + LDB

• Facilitate data retrieval, plotting of e.g. switch statuses

o Prepare for ObsBox ( see LMC on March 13th 2015)• SFP cages per damper module

• install local PCs in BA2

• requires software for the number crunching

o Loop gain tracking• from 14 GeV/c @ INJ to 450 GeV/c @ FT

• need to increase loop gain by factor 32.14, or 30 dB, through the ramp

• analog vs. digital gain (noise issue? limit drive signal?)

13. Feb 2015


Outlook for 2015 - MDs

MD requests aim on• evaluating concepts for improvements of the damping performance

− different implementations for phase shift filters− adaptive feedback control− test a novel damping algorithm− bunch extrapolation (single bunches, ions), beam gap interpolation (in

between batches)

• develop methods to facilitate loop diagnostics− loop information indispensable during commissioning and for setting-up− easy-to-use repeatable measurements: allows re-qualification of

settings/parameters handy e.g. for cycle generation− review potential for per-bunch head/tail activity monitoring

(test with wideband feedback)

• exploitation of new features− real bunch-by-bunch damper (in view of crab cavity tests)− adding a DDS allows for built-in-network analysis− controlled emittance blow-up, beam cleaning, and bunch shaping using

transverse excitation signals

13. Feb 2015

13. Feb 2015


Questions?

THANK YOU!


MD8 – Semi-automated feedback parameter extraction

Objective: extract loop parameters by means of automated measurements

o basis is the classical method with VNA(s)

o automate repeated measurements by means of scripting• adding remote control for VNA(s)

• automatic data collection

• requires interfacing with damper loops, i.e. signal switching

o extract parameters from multiple measurements• closed loop feedback parameters: phase (Hilbert phase shifter, PU mixing coefficients) and delay

(coarse and fine delay)

• but also parameters such as phase and gain equalization, betatron tune, (synchrotron tune)

o Once implemented and proven to work:• this method shall speed up a great deal the setting up

• allows re-qualification of settings/parameters

• scripting could be used compare parameters with LSA settings, and possibly feed back new values

o Measurements done with calibrated VNA(s) serve as reference for other methods/input required for further MDs

13. Feb 2015


MD9 – Feedback performance evaluation with different phase shift filters

Objective: study different implementations of phase shift filters

o original idea for LHC

o further developed for Q20 optics, in view of wide band feedback

o goal: make feedback phase insensitive to tune variations

13. Feb 2015

-0.5 0 0.5 10

0.2

0.4

0.6

0.8

1

-3

-2-1

0.18+1

+2+3

Root Locus

Real Axis

Imag

inar

y A

xis

Q20

20 turns

-0.5 0 0.5 10

0.2

0.4

0.6

0.8

1

-3

-2-1

0.18+1

+2+3

Root Locus

Real Axis

Imag

inar

y A

xis

Q20

20 turns

Phase compensation for sidebands

Notch, 1T delay, phase rotation


MD10 – Injection damping using adaptive feedback control

Objective: extract knowledge of per-bunch oscillation amplitude, and boost gain for individual bunches

13. Feb 2015

MD11 – Test a novel damping algorithm

Objective: extract knowledge of per-bunch oscillation phase, and modulate kick for individual bunches


MD12 – Real bunch-by-bunch damper based on feedback gain equalization

Objective: shaping the time-domain response to generate individual kicks per-bunch, requires feedback gain equalization/gain levelling

o LHC case see W. Hofle, “PERFORMANCE OF THE LHC TRANSVERSE DAMPER WITH BUNCH TRAINS,” WEPME043 - IPAC’13.

o Useful for crab cavity tests

o Individual bunch blow-up (in coast)

o Fully linearized system

13. Feb 2015

LHC ADT


MD13 – Feedback operation powered by built-in VNA

Objective: achieve same results as MD8 with all-built-in mechanisms (VNA)

o analyze 2 or more pick-up signals at once• 50% of the time (2 pick-ups in the SPS)

• ¼ of the time in case of LHC (ultimately 4 pick-ups)

o Same interface to data and parameters as for the damper loops• no external instrument required (SW maintenance, Windows PC)

• valid for operational use

• with gain equalization, i.e. fully linearized system BTF

13. Feb 2015

MD14 – Controlled emittance blowup, beam cleaning, and bunch shaping using transverse excitation signals

Objective: use results from MD13, i.e. the DDS, and noise generators to inject transverse excitation signals for beam manipulations

o aim: have transverse excitations available for MDs


MD15 – Frontend noise evaluation

Objective: Evaluate the frontend performance and its sensitivity to low-amplitude transverse beam signals

o Key word: dithering intentionally apply signal to randomize quantization error

13. Feb 2015

MD16 – On the analysis of feedback stability by increasing the frontend gain after injection damping and during acceleration

Objective: Evaluate the loop stability after increasing the frontend gain and once large oscillation amplitudes have been damped.


MD17 – Performance evaluation using bunch extrapolation/beam gap interpolation

Objective: enhance kick strength for single bunches (iones) and possibly at the tails of batches/trains

o issue: full kick strength only available for frequencies up to < 5 MHz

o Proposed solution: peak hold

13. Feb 2015

MD19 – A different means to determine correct delay adjustment

Objective: Application of different excitation patterns and subsequent correlation to extract delay information.

o Pulse excitation + damping (less destructive)o Modulated sinusoidal (for higher frequencies)o Wavelets + correlation

Dense spacing 100 ns Truly isolated bunches 250 ns

scheme for largespacing

design and performance of the upgraded sps damper after ls1 g. kotzian for the damper team be-rf-fb,...

Documents

sps damper upgrade

upgradedsps damper

sps damper gerd kotzian4

damper teamberf

generalthe transverse

tneltransverse damper

bunch oscillations

single bunch damping