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XFEL 2004 at SLAC m. ferianis
Synchronization and phase monitoring: recent results at ELETTRA
• Synchronization experiment using light sources currently available at Elettra
• Streak camera measurements• CW Phase measurements• Status of the “light-to-light” jitter monitor • Single event phase measurement
Mario Ferianis, Miltcho Danailov
SINCROTRONE TRIESTE, Italy
XFEL 2004 at SLAC m. ferianis
Radiation sources currently available at Elettra
• Sources presently available at ELETTRA:– Bending Magnet S12.2 (diagnostic beam line)
• FWHM=30ps tREP 1MHz
– Storage Ring - FEL• FWHM=8ps tREP 4MHz,
– Table top fs-lasers: Ti:Sa and Cr:LiSaf• FWHM110fs tREP 100MHz
• The SR-FEL is “naturally” synchronized to ELETTRA• The table-top lasers may be locked to an external RF
XFEL 2004 at SLAC m. ferianis
Synchronization experiment of a fs Laser to Elettra Sources
Phase Detector PowerSplitter
LPfilter
Piezodriver
Laser cavity
LaserIN
ReferenceIN
Piezoactuator
fREP2=83.2756MHz
fREF=83.2756MHz
SynchrotronRadiation
2
NUnit
Synchro-scan
Streak Camera
Streak CameraTiming system
fS-SCAN=250MHz
PowerSplitte
r
Laser Timing
Stabilizer
from Storage Ring RF generatorfRF=499.654MHz
PowerSplitter
Divide-by-6Unit
XFEL 2004 at SLAC m. ferianis
View of the Profile Monitor laboratory with the Cr:LiSAF laser and the Streak Camera
XFEL 2004 at SLAC m. ferianis
laser
2ns
10ns
Streak Camera acquisition:Multi Bunch (2ns spacing) beam+laser @99.93MHz
fREP1=fRF5 = 99.9308MHz
XFEL 2004 at SLAC m. ferianis
880ps
864ns:1 ELETTRA revolution
18 laser pulses
4 Bunch beam (216ns/bunch) + [email protected] (12ns)
12ns
12ns
440ps
fREP2 =fRF6 = 83.2756MHz
XFEL 2004 at SLAC m. ferianis
5 accumulated acquisitions
Laser phase oscillationsdue to external kick
Elettra 4 bunch beam
180ps
880ps
69ms
XFEL 2004 at SLAC m. ferianis
All three sources
FEL staff courtesy
FELmacropulses
CR:LiSAF trace@83MHz
The “old, good ELETTRA”4bunch @ 4.6MHz
6.7ms
XFEL 2004 at SLAC m. ferianis
Phase Detector AD8302 (02.7GHz) Analog Devices
EX-OR
Low-pass filter
Vector analyser on a chip
XFEL 2004 at SLAC m. ferianis
Vphase vs. frequency @100MHz:Ftot=100kHz TOT=0.135deg
99,940,000
99,960,000
99,980,000
100,000,000
100,020,000
100,040,000
100,060,000
1 67 133 199 265 331 397 463 529 595 661 727 793 859 925 991 105711231189125513210.4670
0.4672
0.4674
0.4676
0.4678
0.4680
0.4682
0.4684
0.4686
0.4688
0.4690
frequency phase
tot=0.135deg; step=13.5mdeg
VSTEP=0.135mV
1deg@100MHz =27.7ps;min=0.187ps (step /2)1deg@3GHz =0.926ps; min=6.25fs
XFEL 2004 at SLAC m. ferianis
Comparison of two phase measurements
AD 8302 Phase
Detector
PowerSplitter
Ceramic Band PassLC filter
Piezo
driver
Laser cavity
LaserIN
ReferenceIN
Piezoactuator
fREP2=83.2705MHz
PowerSplitter
Laser Timing
Stabilizer
Photo diode
R&Sgenerator
A
B
1) V PHASE
Spectrum Analyzer HP3589
Digital Oscilloscope
TEK 7104
2) Phase OUT
XFEL 2004 at SLAC m. ferianis
Spectra of phase noise of the laser locked @ 83.2705MHz
CLX 1100Phase OUTPUT
AD8302 Vphase
XFEL 2004 at SLAC m. ferianis
Locked laser damping timeto an external kick
AD8302 Vphase
100mV/div
CLX phase OUT
20mV/div
300ms
XFEL 2004 at SLAC m. ferianis
Experiment set-up in the SRPM hutch
Phase Detector PowerSplitter
LPfilter
Piezodriver
Laser cavity
LaserIN
ReferenceIN
Piezoactuator
fREP2=83.2756MHz
fREF=83.2756MHz
SynchrotronRadiation
Band passfilter 18th
harmonic
Direct light-to-lighton-line jitter
measurement
Sub-psPhase
comparator
2
NUnit
Synchro-scan
Streak Camera
Streak CameraTiming system
fS-SCAN=250MHz
PowerSplitte
r
Laser Timing
Stabilizer
from Storage Ring RF generatorfRF=499.654MHz
PowerSplitter
Divide-by-6Unit
XFEL 2004 at SLAC m. ferianis
AD8302 phase measurement: 6.5MHz filter output vs. reference
(83.275MHz)
V=330mV 33deg
Plot of the phase difference measured with 1GHz scope [deg]
230
240
250
260
270
280
290
0 100 200 300 400time [ns]
XFEL 2004 at SLAC m. ferianis
FERMI Phase Measurements
• The term “Phase measurement” generally refers to measuring the phase of a signal w.r.t. a reference.
• Rigorously, we can speak about phase when dealing with sinusoidal signals, eventually sinusoidal bursts.
• For FERMI applications, two different “phase” measurements* are needed:– sinusoidal to reference (CW/CW burst measurement)
– pulse to reference (single event measurement)
• For pulsed signals, the phase difference can be defined as the time interval bewteen pulse arrival and next zero crossing of the reference signal.
• The most critical measurement is the second one due to:– required (sub-) ps resolution
– ultra short pulses of limited amplitude (low energy signals)
– low repetition rate (1 to 100Hz)
* APL - Dip. Elettronica ed Informatica, Trieste University and AllTEK Innovation s.r.l.
XFEL 2004 at SLAC m. ferianis
Proposed scheme for single event phase measurement
Pulse stretcher
Beam pulsesignal
Reference signal
“0” Xingdetector
(low jitter)Hold off
Hold off
Time interpolator(SiGe logic)
Pulse stretcher
“0” Xingdetector
(low jitter)
APL - Dip. Elettronica ed Informatica, Trieste University and AllTEK Innovation
XFEL 2004 at SLAC m. ferianis
Zero X-ing detector prototypetests with Pulse Generator:
tPULSE=300ps; APULSE PK-PK=90mV; fREP=10kHz
TRIGGER
CSA803CSampling
Scope
BW=20GHz
INPUT
HP8131A500MHz
Pulse Generator 10mV/div100ps/div
JitterRMS=1. 37ps
TRIGGER
CSA803CSampling
Scope
BW=20GHz
INPUT
HP8131A500MHz
Pulse Generator
“0” X-ingdetector
IN OUTunder
test
100mV/div100ps/div
JitterRMS=1.94ps
Apk-pk=600mV*10 (20dB att) =6V
APL - Dip. Elettronica ed Informatica, Trieste University and AllTEK Innovation s.r.l.
XFEL 2004 at SLAC m. ferianis
tRISE =18pstPULSE =30psAPULSEpk-pk=250mV
Zero X-ing detector prototype tests @ fREP=10Hz
fs laser + Pockels Cell + 25GHz Photodiode
New FocusPhoto DiodeBW=25GHz
“0” Xingdetector
under test
IN OUT
TEK Real time ScopeTRIGGER
CH1
BW=1GHz
CH2
Cr:LiSAFfs laser
PockelsCell
HVdriver
SPLITTER
Amplifier7GHz
Pulsegenerator
-10dB
2Vpk-pk*3.17=6.3V
APL - Dip. Elettronica ed Informatica, Trieste University and AllTEK Innovation
XFEL 2004 at SLAC m. ferianis
Future work
• To complete direct light-to-light phase measurements in 4B mode– Bending Magnet to external fs laser– Bending Magnet to SR-FEL– SR-FEL phase during Q-switch w.r.t. a non modulated RF (?)
• To complete jitter reduction work in the Profile Monitor hutch• To implement phase measurement at low rep rate
– 10Hz i.e. FERMI
• To characterise laser jitter in fiber optic transmission• To study the feasibiltiy of an in-house improved version of
phase locking system (timing stabilizer)