Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 Plans for FONT3 and Future Feedback Experiments...

Philip Burrows 2 nd Nano Workshop, KEK 11/12/04

Plans for FONT3 and Future Feedback Experiments

Philip Burrows

Queen Mary, University of London

• ILC system overview • FONT2 @ NLCTA: reminder• FONT3/FEATHER plans at ATF • Future feedback experiments


• FONT:

Queen Mary: Philip Burrows, Glen White, Glenn Christian,

Hamid Dabirikhah, Tony Hartin, Stephen Molloy, Christine Clarke

Daresbury Lab: Alexander Kalinin, Roy Barlow, Mike Dufau

Oxford: Colin Perry, Gerald Myatt

SLAC: Joe Frisch, Tom Markiewicz, Marc Ross, Chris Adolphsen, Keith Jobe, Doug McCormick, Janice Nelson, Tonee Smith, Steve Smith, Mark Woodley

• FEATHER:

KEK: Nicolas Delerue, Toshiaki Tauchi, Hitoshi Hayano

Tokyo Met. University: Takayuki Sumiyoshi, Fujimoto

• Simulations: Nick Walker (DESY), Daniel Schulte (CERN)

International Fast FB Collaboration


Beam-based feedback in ILC

• ‘Slow’ orbit (upstream BDS, linac)

• Pulse-to-pulse (ILC: 5 Hz): extensive experience at SLC (120 Hz)

• Intra-train (‘bunch-to-bunch’):

principal correction scheme in TESLA TDR

• Integrated simulations linac -> IP + ground motion, wakefields …

(PLACET, LIAR, MERLIN, GUINEAPIG, CAIN)

• Hardware prototyping of (fast analogue) critical components:

BPM processors, FB, drive amplifiers + closed-loop beam tests


Intra-train Beam-based Feedback

Intra-train beam feedback is last line of defence against relative beam misalignment

Key components:

Beam position monitor (BPM)

Signal processor

Fast driver amplifier

E.M. kicker

Fast FB circuitTESLA TDR: principal IR

beam-misalignment correction


Zero-degree crossing angle (TESLA TDR)

FB BPM

Upstream

kicker(s)


‘Large’ crossing angle (NLC)

FB BPMkicker


Intra-train feedback performance (White/QMUL)

0 100 200 300 400 500 6000

1

2

3x 10

34

Bunch #

Lu

min

os

ity

/ c

m-2s

-1

y position FB:

restore collisions

within 100 bunches1 seed:

post-BBA

+ GM

+ wakes

y position scan:

optimise signal

in pair monitor (+4%)

y angle scan

OPTIMAL

LUMINOSITY


(FONT1 +) FONT2: beamline configuration

Dipole and kickers

BPMs


FONT1 + FONT2 amplifiers

Bandwidth limited (30 MHz)

FONT1 3-stage tube amp FONT2 solid-state amp

Up to 10A, 350V Up to 10A, 100V (x2)


FONT2: expected latency

• Time of flight kicker – BPM: 6ns• Signal return time BPM – kicker: 10ns

Irreducible latency: 16ns

• BPM processor: 18ns• FB circuit: 4ns• Amplifier: 12ns• Kicker fill time: 3ns

Electronics latency: 37ns

• Total latency expected: 53ns


FONT2 results: feedback BPM

Feedback on

Beam flattener on

Beam starting positions

Delay loop on

beam start beam end

1 2 3 4


FONT2 final results (Jan 22 2004)

Super-fast modified configuration:

Latency 54ns

Correction 14:1(limited by gain knob resolution)

dis

per

sio

n


FONT3

Original aim:

Demonstrate micron-level stabilisation of 1.3 GeV ATF beam with latency c. 20 ns

EQUIVALENT TO:

nanometer stabilisation of 250-500 GeV LC beam with same lever arm …

-> demonstrate actual BPM processor and amplifier for warm LC

Worth completing, though low latency no longer critical


FONT3 outline

Adjustable-gap kicker

BPM ML11X

Feedback

SuperfastBPM processor

Superfastamplifier

BPM ML12X

BPM ML13X

Aim:

TOTAL latency

< 20 ns


FONT3: latency budget

• Time of flight kicker – BPM: 4ns• Signal return time BPM – kicker: 6ns

Irreducible latency: 10ns

• BPM processor: 5ns• Amplifier + FB: 5ns

Electronics latency: 10ns

• Total latency budget: 20ns

Will allow 56/20 = 2.8 periods during bunchtrain


FONT3: beamline configuration

kicker BPMML11X


FONT3 BPM processor (Molloy)

Latency budget 5ns

Superfast scheme: down-mix to baseband using 714 MHz LO

First tests June 2004

Now testing improvedscheme w. different filteroptions

Final version ready forMarch 2005


FONT3 amplifier (Perry)

• Detailed design in progress

• Tradeoff between drive and latency

latency < 5 ns constrains drive significantly

• Lever-arm amplifier -> BPM very small: c. 1.1m

• Solid state, low power ( < 100W)

• Aiming for beam kick up to 20-30 microns at ML11X

• First version will be tested in March 2005

• Slightly improved version possible for June 2005


FONT3 DAQ/control (White)

• Almost certainly use our 2 scopes (8 channels):

FB BPM output

drive signal to amplifier

2 witness BPM y signals

Delay loop signal

2 witness BPM y signals …

• Auto control of corrector (ZV7X?) to produce controlled

incoming beam offsets at FB BPM


FONT3 beam requirements

• 20-bunch train (56 ns)essential in order to see action of delay loop

• Uniform charge within train (better than +- 10%)essential since no time for charge normalisation

• Flat bunch-bunch position profile within traindesirable

• Small bunch-bunch position jitter within train (few microns)essential

• Small train-train jitter (few microns)essential to avoid amplifier saturation (c. 20 microns)


FONT3 jitter monitor (Kalinin)

• Aim to measure bunch-bunch

jitter at micron level

• First tests June 2005:

bunches resolved, but position

resolution > 10 microns

(common-mode rejection issues)

• Improved processors being

tested now (BPMs 8, 10, 13)

+ 2 BPMs in ring


Possible Future Experimental Programme (1)

Short-term: expect to finish FONT3 in June 2005

Long-term:

demonstrate robust intra-train FB system for ILC, based on digital signal processing, and ideally test with beam:

requires long bunchtrain with 337 ns bunch spacing

> 2006 (?): 20 bunches x 337ns at ATF/ATF2 would be very attractive

2005-6: 3 (or 4) bunches x 100 ns at ATF would also be interesting:

stabilise last bunch at 100 nm level as part of Nano project

also feed-forward studies ring -> extraction line?


2006: ‘Nano’ Project at KEK ATF

FONT/FEATHER-style feed-forward and/or feedback


Possible Future Experimental Programme (2)

Study of performance of FB hardware in realistic IR environment: e+e- and gamma backgrounds

Make e+e- and gamma fluxes in SLAC A-line:

install BPM and study noise/long-term radiation effects

Concerns about EM pickup in FB BPM – test in IR mockup?

Intra-train beam feedback technology widely applicable:

emergency fast beam abort (DONT)?

beam position stabilisation for diagnostics:

laserwire, bunch-length monitor, Shintake monitor …

Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 Plans for FONT3 and Future Feedback Experiments...

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