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
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
• 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
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
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
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
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
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
Zero-degree crossing angle (TESLA TDR)
FB BPM
Upstream
kicker(s)
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
‘Large’ crossing angle (NLC)
FB BPMkicker
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
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
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
(FONT1 +) FONT2: beamline configuration
Dipole and kickers
BPMs
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
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)
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
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
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
FONT2 results: feedback BPM
Feedback on
Beam flattener on
Beam starting positions
Delay loop on
beam start beam end
1 2 3 4
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
FONT2 final results (Jan 22 2004)
Super-fast modified configuration:
Latency 54ns
Correction 14:1(limited by gain knob resolution)
dis
per
sio
n
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
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
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
FONT3 outline
Adjustable-gap kicker
BPM ML11X
Feedback
SuperfastBPM processor
Superfastamplifier
BPM ML12X
BPM ML13X
Aim:
TOTAL latency
< 20 ns
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
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
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
FONT3: beamline configuration
kicker BPMML11X
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
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
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
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
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
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
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
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)
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
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
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
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?
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
2006: ‘Nano’ Project at KEK ATF
FONT/FEATHER-style feed-forward and/or feedback
Philip Burrows 2 nd Nano Workshop, KEK 11/12/04
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 …
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