Transcript RF, Phase Stability, SPPS Experience

LCLS RF Stability Requirements
LCLS Requirements
The SLAC Linac
SLAC Linac Stability Data
SPPS Measurements
LCLS RF System
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [email protected]
LCLS INJECTOR / LINAC
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [email protected]
LCLS Machine Stability Tolerance Budget
X-band
April 29, 2004
LCLS RF
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.
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [email protected]
LINAC RF and Timing System
Master Oscillator is
located 1.3 miles
from LCLS Injector
PEP PHASE SHIFT ON MAIN DRIVE LINE
April 29, 2004
LCLS RF
1.3 Miles to
LCLS Injector
MDL RF with TIMING Pulse – Sync to DR
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [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
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [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
April 29, 2004
LCLS RF
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, P. Emma, P. Krejcik
akre@ , emma@, [email protected]
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.
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [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.
April 29, 2004
LCLS RF
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, P. Emma, P. Krejcik
akre@ , emma@, [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
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [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
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [email protected]
Linac Phase Stability Estimate Based on Energy
Jitter in the Chicane
BPM
1 GeV
9 GeV
SLAC Linac
30 GeV
sE/E0  0.06%
e- Energy (MeV)
D 21/2 < 0.1 deg (100 fs)
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [email protected]
LCLS Phase Noise
Associated Time Referenced to Beam Time
LCLS Laser
Need to Measure
10uS to 1mS
LCLS Gun
SLED / Accelerator
Phase Detector (Existing)
Distribution System
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
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [email protected]
Phase Noise of SLAC Main Drive Line
Noise Floor of About -120dBc/38Hz = -136dBc/Hz = 120fS 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
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [email protected]
SPPS Laser Phase Noise Measurements
Phase Noise of Output of Oscillator with Respect to Input
Measurement done at 2856MHz with External Diode
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [email protected]
Jitter determination from Electro Optic sampling
A. Cavalieri
Principal of
temporal-spatial correlation
single pulse
Line image
camera
EO xtal
analyzer
polarizer
Er
30 seconds, 300 pulses:
April 29, 2004
LCLS RF
width
sz = 530 fs ± 56 fs rms
centroid
Dt = 300 fs rms
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [email protected]
LINAC SECTOR 20 – LCLS INJECTOR
RF Stability < 50fS rms : Timing/Trigger Stability 30pS rms
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [email protected]
LCLS RF System – Sector 20 Layout
100ft ½” Heliax = 0.3ºS/ºF
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [email protected]
Beam Trigger for User Facility
Wide Bandwidth – Rising Edge of 8nS ?
Low Phase Noise – 30fS Stability
Design Needs Input
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [email protected]
LCLS RF System
Injector RF – FY06
Upgrade of existing system / Lower Noise Timing
requirements
Injector/L1 Phase Reference System
Phase and Amplitude measurement system
Solid State Sub-Boosters
Beam Phase Monitor System
X-Band RF system – FY06
Linac Phase Reference System – FY07
Linac Feedback Control – FY07
Far Hall Trigger – FY08
Feedback Development – FY07
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [email protected]
Near Term (6 Month) Tasks
Measure Phase Noise and Response of
SPPS Laser
Install New Oscillator, -157dBc/Hz floor, in
Accelerator and Measure Phase Noise
Determine Type of RF Phase and Amplitude
Measurement System
April 29, 2004
LCLS RF
R. Akre, P. Emma, P. Krejcik
akre@ , emma@, [email protected]