Transcript Phase noise in RF distribution

XFEL Short Bunch Measurement
LCLS
Drive
Laser
Timing
and Timing Workshop
Stability Measurements
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
LCLS Machine Stability Tolerance Budget
800fS rms
X-band
X-
RMS tolerance budget for
<12% rms peak-current jitter
or <0.1% rms final e− energy
jitter. All tolerances are rms
levels and the voltage and
phase tolerances per klystron
for L2 and L3 are Nk larger,
assuming uncorrelated errors,
where Nk is the number of
klystrons per linac.
P. Emma
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
LINAC RF and Timing System
Master Oscillator is
located 1.3 miles
from LCLS Injector
PEP PHASE SHIFT ON MAIN DRIVE LINE
July 26, 2004
XFEL Short Bunch Measurement and Timing
1.3 Miles to
LCLS Injector
MDL RF with TIMING Pulse – Sync to DR
R. Akre
[email protected]
Linac Phase Reference System
Main Drive Line - 3 1/8 Rigid Coax Anchored to Concrete Floor Every Sector
Phase Reference Line - Each Sector Independent 1/2 “ Heliax
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
Linac Phase Reference System
Phase Reference Line
Main Drive Line
½ inch Heliax Cable with 1.2 Watts
3 1/8 inch Rigid Coax with 30watts
Phase Reference for 8 PADs (Klystrons)
in the sector
Length = 31 Sectors, 15.5 furlongs
2miles, 3km : Velocity = 0.98c
Length = 1 Sector, 0.5 furlongs, 332ft,
400kS in ½” Heliax
Anchored at each sector next to
coupler and expansion joint
Temperature Coefficient 4ppm/C
Purged with dry nitrogen
Waveguide Water T = 0.1C rms
Phase Length Range 100S/Year
85% of the cable is regulated to 0.1C
rms
15% may see variations of 2C rms
Average Temperature Variation = 0.4C
rms
 = 0.64S rms
July 26, 2004
XFEL Short Bunch Measurement and Timing
Phase Length Range 40S/Day
Accuracy Based on SLC Fudge
Factor
0.5S/Sector Total Variation
0.2S rms / Sector
R. Akre
[email protected]
Phase Noise of SLAC Main Drive Line
Old Oscillators
Noise Floor of About -120dBc/38Hz = -136dBc/Hz = 120fS rms Jitter in 5MHz BW
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
Phase Noise of SLAC Main Drive Line
New Oscillators
10  log( RBW)  15.815
Timing Jitter
SSB Spectral Density dBc/RBW @ 476MHz
0.2
60
80
Picoseconds rms
0.15
dBc/RBW
100
120
140
0.1
0.05
160
180
10
100
1 10
3
1 10
1 10
Frequency Hz
4
5
1 10
6
RBW  38.147
Linac MDL Sector 0 7-13-04 (mdl-20mF.dat)
1 10
7
0
10
100
3
4
5
1 10
1 10
1 10
Frequency Hz - Start of Integration
1 10
6
1 10
Linac MDL Sector 0 7-13-04 (mdl-20mF.dat)
Noise Floor of About -133dBc/38Hz = -149dBc/Hz < 60fS rms Jitter in 5MHz BW
New Oscillators Have a noise floor of -157dBc/Hz @ 476MHz
11fS rms Jitter in 5MHz BW or 31fS rms Jitter in 40MHz BW
Above plots give upper limits, much of which could be from measurement system
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
7
SLAC Linac RF
The PAD measures phase noise
between the reference RF and the
high power system. The beam sees
3.5uS of RF from SLED.
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
LINAC RF MEETS ALL LCLS SPECIFICATIONS
for 2 Seconds when running well
Amplitude fast time plots show pulse to pulse
variation at 30Hz. Standard deviation in percent
of average amplitude over 2 seconds are
0.026% for 22-6 and 0.036% for 22-7.
July 26, 2004
XFEL Short Bunch Measurement and Timing
Phase fast time plots show pulse to pulse variation
at 30Hz. Standard deviation in degrees of 2856MHz
over 2 seconds for the three stations are
0.037 for 22-6 and 0.057 for 22-7.
R. Akre
[email protected]
LINAC RF is Out of LCLS Specs in 1 Minute
Phase
Amplitude
22-6
22-6
1.2 Deg pp
0.20%pp
Amplitude
Phase
22-7
22-7
0.43%pp
1.2 Deg pp
14 minutes data taken using the SCP correlation plot
Note that 22-6 and 22-7 are correlated in phase and amplitude
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
Phase as Seen by Electron is Difficult to
Measure
]
Accelerator Water Temperature Effects on SLED Phase[1
The tuning angle of the SLED cavity goes as:
 = tan -1 (2QLT),
Where T = L/L = -/
QL= 17000
= 10-5 / F Thermal expansion of copper.
=tan -1 (0.34T)
Where T is in F.
For small T, (S)= 20T(F)
The relation between the tuning angle  and the measured output phase of the klystron 
varies with the time after PSK with about the following relation:
 /  = 0.35 just after PSK (S)= 7T(F)
 /  = 0.50 800nS after PSK (S)= 10T(F)
 / T~ +8.5 S / F for SLED Cavity
Accelerator Water Temperature Effects on the Accelerator Phase[2]
The phase change of the structure goes as follows:
 =  f
Where  = phase through structure
 = Angular frequency
f = Filling time of structure
 =  f = / x f
/ = -L/L = -T = -10-5 T / F for copper
 = -10-5 T / F22856MHz0.84S = -0.15 T rad/F = -8.6 T S / F
 / T = -8.6 S / F for Accelerator Structure
Water / Accelerator Temperature Variation is 0.1F rms
 through structure is 0.86F rms
[1]
[2]
July 26, 2004
XFEL Short Bunch Measurement and Timing
Info from D. Farkas
Info from P. Wilson
R. Akre
[email protected]
Phase as Seen by Electron is Difficult to Measure
Accelerator Water Temperature Effects on the Phase Through the
Accelerator -8.6 S / F
SLAC Linac Accelerator Water Temperatures T< .08Frms
Phase Variations Input to Output of Accelerator > 0.5ºS-Band rms
Single Measurement Can’t Determine the Phase the Beam
Sees Passing Through the Structure to LCLS Specifications
Feedback on Input Phase, Output Phase, Temperature, Beam
Based Parameters (Energy and Bunch Length) is Required to
Meet LCLS Specifications
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
LINAC SECTOR 20 – LCLS INJECTOR
RF Stability < 50fS rms : Timing/Trigger Stability 30pS rms
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
LCLS RF System – Sector 20 Layout
100ft ½” Heliax = 0.3ºS/ºF
Tunnel Temperature < 0.1deg F rms
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
SPPS Laser Phase Noise Measurement
R. Akre, A. Cavalieri
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
SPPS Laser Phase Noise Measurements
Phase Noise of Output of Oscillator with Respect to Input
Measurement done at 2856MHz with External Diode
R. Akre, A. Cavalieri
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
SPPS Laser Phase Jump Tracking
R. Akre, A. Cavalieri
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
SPPS Laser Phase Jump Tracking
Laser Phase Error – Output Phase to Input Reference - Modulated with 1 Hz Square Wave
0.25pS pk Square Wave
k1  0 
kpts  1
2
0.25pS pk Square Wave
picoseconds - phase error
picoseconds - phase error
0.4
0.2
0
0.2
143.8
143.9
144
144.1
milliseconds
144.2
144.3
0
0.5
26.4
26.6
26.8
27
milliseconds
27.2
526.8
527
milliseconds
527.2
27.4
SPPS LASER 1 Hz Phase Oscillation Square Wave 2pS pkk1  0  kpts  1
2
(Phase Shift In 400k 16mV 3T.dat) 400k SPS
0.1
1
0
picoseconds - phase error
picoseconds - phase error
0.5
1
26.2
144.4
SPPS LASER 1 Hz Phase Oscillation Square Wave 0.25pS k1
pk  0  kpts  1
2
(Phase Shift In 400k 2mVT.dat) 400k SPS
0.1
0.2
0.3
0.4
0.5
643.8
kpts  1
2
1
0.6
0.4
143.7
k1  0 
643.9
644
644.1
644.2
milliseconds
644.3
644.4
SPPS LASER 1 Hz Phase Oscillation Square Wave 0.25pS pk
(Phase Shift In 400k 2mVT.dat) 400k SPS
July 26, 2004
XFEL Short Bunch Measurement and Timing
0.5
0
0.5
1
526.2
526.4
526.6
527.4
SPPS LASER 1 Hz Phase Oscillation Square Wave 2pS pk
(Phase Shift In 400k 16mV 3T.dat) 400k SPS
R. Akre
[email protected]
SPPS Laser Amplitude of Phase Transfer Function
SPPS Laser Oscillator Amplitude Transfer Function
10.0
5.0
Amplitude dB
0.0
-5.0
-10.0
-15.0
-20.0
-25.0
0
5000
10000
15000
20000
25000
30000
35000
Frequency Hz
Phase Modulation placed on RF Reference and measured on Diode at Laser output.
During the Blue part of the curve the modulation amplitude was reduced by 12dB to
prevent laser from unlocking. Data taken 10/22/03
R. Akre, A. Cavalieri
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
Linac Phase Stability Estimate Based on Energy
Jitter in the Chicane
BPM
1 GeV
SLAC Linac
30 GeV
9 GeV
sE/E0  0.06%
e Energy (MeV)
 21/2 < 0.1 deg (100 fs)
July 26, 2004
XFEL Short Bunch Measurement and Timing
P. Emma
R. Akre
[email protected]
Jitter determination from Electro Optic sampling
A. Cavalieri
P. Krejcik
Principal of
temporal-spatial correlation
single pulse
Line image
camera
EO xtal
analyzer
polarizer
Er
30 seconds, 300 pulses:
width
centroid
sz = 530 fs ± 56 fs rms
July 26, 2004
XFEL Short Bunch Measurement and Timing
t = 300 fs rms
R. Akre
[email protected]
Electro-Optical Sampling
200 m thick ZnTe crystal
Single-Shot
e
Timing Jitter
(20 Shots)
<300 fs
Ti:Sapphire
laser
e temporal information is encoded
on transverse profile of laser beam
170 fs rms
Adrian Cavalieri et al., U. Mich.
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
LCLS Phase Noise
Associated Time Referenced to Beam Time
LCLS Laser
10uS to 1mS
LCLS Gun
SLED / Accelerator
Phase Detector (Existing)
Distribution System
Need to Measure
~200uS
1.1uS
3.5uS
30nS
200nS
1km @ c-97%c=100nS
Far Hall Trigger
2uS
3km @ c-80%c=2uS
-3.5us SLED
Starts to Fill
-2uS Far Hall Trig
RF Starts Trip
-1.1uS Gun
Starts to Fill
Beam Time 0
Reference
TIME
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
Beam Trigger for User Facility
Single Pulse with 30fS stability (1Hz to 3GHz BW)
Tightest Noise Tolerance of LCLS
Wide Bandwidth – Narrow Bandwidth
ECL chips have 150pS rise times
Low Phase Noise
30fS Stability today
10fS Stability tomorrow
1fS ???
Design Needs Input
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]
NO CONCLUSIONS
July 26, 2004
XFEL Short Bunch Measurement and Timing
R. Akre
[email protected]