Sub-ps (and sub-micrometer) developments at ELETTRA Mario Ferianis SINCROTRONE TRIESTE, Italy
The ELETTRA laboratory ELETTRA is a 3 rd generation synchrotron light source in Trieste (I) since 1993 up to 6000 user hours/year 1GeV LINAC + 2.4GeV Storage Ring ~ 20 active beam lines: Insertion Devices and Bending Soft X-rays, VUV-UV, VIS (diagnostics), IR Technical Optimization Study (in collaboration with LBL, MIT & SLAC) underway for a seeded FEL, based on the upgrade of the existing LINAC new Photo-cathode GUN energy up to 1.2GeV FEL 1: 100 40nm FEL 2: 40 10nm
Storage Ring Free Electron Laser: 4 bunches spaced by 216ns=roundtrip time of the optical cavity the experimental setting is the following: beam energy: 900 MeV, beam current (four bunches): 10 ma, laser wavelength: 250 nm, Free running Q-Switch courtesy: G. De Ninno
Need for synchronization Up to now most of the experiments have been using the average photon flux In a pump-probe scheme, one pulse excites the sample whereas the second one takes the picture Different combinations of the available sources (SR, SR-FEL, external fs Lasers) can be used: we need to synchronize at the pico second level As an experiment, we lock a fs laser to the electron bunches of the Storage Ring, by using a low jitter (<1ps RMS ) electronic module. To check for jitter (short term) and stability (long term) between sources To implement high resolution phase measurement
Lay out of section 1 of the ELETTRA Storage Ring with diagnostics Optical Laboratory fs Cr:LiSAF laser Streak Camera Master RF from the accelerating cavities
R&S generator Power Splitter Minimizing locked laser phase noise Redundant high resolution phase measurement A AD 8302 Phase Detector 1) V PHASE Spectrum Analyzer HP3589 Digital Oscilloscope TEK 7104 Reference IN Laser Timing Stabilizer Piezo driver Laser IN Piezo actuator B Power Splitter Laser cavity 2) Phase OUT f REP2 =83.2705MHz Band Pass LC filter Photo diode Measured Laser phase noise: 0.1ps RMS
Locked laser damping time to an external kick AD8302 V phase 300ms 100mV/div CLX phase OUT 20mV/div
Noise Spectral Density Analog Devices data sheet, Phase Detector AD8302
Noise measurement set-up Phase Detector AD8302 (0 2.7GHz) POUT=-30dBm BW=20MHz R&S V SMX NOISE RMS =5.7mV RF generator P OUT = -30dBm...0dBm Power splitter Phase Master POUT=0dBm 190 Coax BW=2.5MHz (90 o @70MHz) V NOISE RMS =314µV AD8302 Amp&Phase Detector LP filter BW=2.5MHz TEK 5104 BW=1GHz, 20MHz
Measured data on Noise amplitude (RMS) vs. Bandwidth (BW=1GHz, 20MHz, 2.5MHz) V PH scaling=10mv/deg Input level [dbm] Full scope BW=1GHz -30 5.9mV 0.59deg Measurement bandwidth BW limit LP filter BW=20MHz BW=2.5MHz 5.7mV 4.43mV 0.57deg 0.44deg DVM 7 1/2 bits BW=1Hz - 0 450µV 0.045deg 407µV 0,040deg 314µV 0,031deg 4.7µV 0,47mdeg
Stability tests on AD8302: data @1Hz on DVM 10mV/deg 10µV=1mdeg (100MHz...2.7GHz)
Resolution measurement set-up Phase Detector AD8302 (0 2.7GHz)
V phase vs. frequency @100MHz: F tot =100kHz Φ TOT =0.135deg frequency phase 100,060,000 100,040,000 100,020,000 100,000,000 Φ tot =0.135deg; Φ step =13.5mdeg 0.4690 0.4688 0.4686 0.4684 0.4682 0.4680 99,980,000 99,960,000 99,940,000 V STEP =0.135mV 1deg@100MHz =27.7ps; Τ min =0.187ps ( Τ step /2) 1deg@3GHz =0.926ps; Τ min =6.25fs ERL 05 1 67 Workshop 133 199 265 331 397 463 529 Mario 595 Ferianis 661 727 793 859 925 991TJNAF, 10571123118912551321 march 20, 2004 0.4678 0.4676 0.4674 0.4672 0.4670
from Storage Ring RF generator f RF =499.654MHz Power Splitter Final configuration for the Synchronization experiment Streak Camera Timing system 2 f S-SCAN =250MHz N Unit Synchroscan Streak Camera Synchrotron Radiation pulses @4.626MHz Divide-by-6 Unit f REF = 83.2756MHz Power Splitter Phase Detector Power Splitter Laser Timing Stabilizer Reference IN Laser IN f REP2 =83.2756MHz Piezo driver LP filter Piezo actuator Laser cavity
Streak Camera and Cr:LiSAF laser in the diagnostics Optical Laboratory
Storage ring vs. external Laser frequencies f RF =499.654MHz Multi Bunch 1 bunch / 2ns 4-Bunch SR-FEL 1 bunch / 216ns 5 f REP1 =f RF 5 = 99.9308MHz 6 f REP2 =f RF 6 = 83.2756MHz t LASER = 10.006ns 1 laser pulse / 5 bunches Coincidence laser on same bunch: every 5 revolutions (864/10 = 86.4ns) t LASER = 12.006ns 18 laser pulses / bunch (4B) (12ns*18=216ns) Coincidence laser on same bunch: at each turn
Two streak camera acquisitions (synchroscan): Multi Bunch beam + laser Slow time Slow time 2ns 10ns laser 880ps Fast time Fast time f REP1 =f RF 5 = 99.9308MHz
4Bunchbeam (216ns/bunch) + laser@83.275mhz (12ns) f REP2 =f RF 6 = 83.2756MHz 880ps Jitter laser-to-synchrotron ~1ps RMS 12ns 18 laser 12ns pulses 864ns: 1 ELETTRA revolution 440ps
Long time (69ms) acquisitions: 5 accumulation Elettra 4 bunch beam 69ms 880ps Laser phase oscillations due to external kick 180ps
All three sources... CR:LiSAF trace @83MHz Slow time 6.7ms FEL macropulses FEL staff courtesy The old, good ELETTRA 4bunch @ 4.6MHz
Beam Orbit stabilization at the center of the Insertion Device straight section
LEFT: std BPM mounted RIGHT: new LGBPM to the Q-pole faceplate indep. Support+ref column
Capacitive Sensor specifications (by Physik Instrumente) It provides sub-nm resolution over a 300µm range It s linear: <0.05% Low temp drift: -30ppm/ o K It has 3 khz bw It provides a noncontact measure M. Ferianis APM 28/10/1999
Two pairs of Capacitive Sensors monitoring the X&Y position of Low Gap BPM M. Ferianis Apr2001
96,00 95,80 95,60 95,40 95,20 95,00 94,80 94,60 94,40 94,20 Noise 27 Oct. on 1999 real - position Short acq. readings - 4min. in the machine tunnel at 1Hz 23,00 22,90 22,80 22,70 22,60 22,50 22,40 22,30 22,20 22,10 94,00 22,00 8.50 8.51 8.52 8.53 8.54 y RMS = 30nm ; y pk-pk = 100nm
Drift of the Low Gap BPM vertical pos. during re-fill of the Storage Ring Energy, Current and dy vs. time µm 103,00 102,00 101,00 100,00 99,00 98,00 97,00 96,00 95,00 94,00 93,00 19.00 19.28 19.57 20.26 20.55 21.24 21.52 2000 1500 1000 500 0 MeV / ma
RUN 71; 12-13/04/01 Ypos Xpos Tvac-dpwnstream T-bpm-ext Tvac-upstream 90.00 50.00 88.00 45.00 86.00 84.00 82.00 80.00 78.00 76.00 74.00 72.00 40.00 35.00 30.00 25.00 70.00 17.02.45 19.08.10 21.13.35 23.18.60 01.24.25 03.29.50 05.35.15 07.40.40 09.46.05 20.00
Joint Time Frequency Analysis based on LabView tool LOW GAP n.1, Cap. Sens. Fast Acq.@1kHz, VERT plane
Model of the Support System: vertical axis Alu. holder Cap. Sens. pair LG-BPM Alu. holder α carb. fiber = -0.1µm/(m o C) α steel = 18µm/(m o C) α aluminum = 22µm/(m o C) Lsupport = 1.1m hlg-bpm/2 = 0.025m hholder = 0.01m LG-BPM Steel support L= T air *L supp. + T BPM *(h BPM +h eq. ) Carbon Fiber Reference Column
Measured Y vs. Computed Y Ymeas Ycomp DYbpm DYsupp DYeq. 80.00 70.00 60.00 50.00 40.00 30.00 20.00 10.00 0.00 25.00 20.00 15.00 10.00 5.00 0.00-5.00-10.00-15.00-20.00-25.00 14.04.07 18.14.57 22.25.47 02.36.37 06.47.27 10.58.17 M. Ferianis October 2000
Measured X vs. Computed X micron Xpos DXtot DXbpm DXair 80 70 60 50 40 30 20 10 0 14.04.07 22.25.47 06.47.27 15.09.07 23.30.47 07.52.27 16.14.07 00.35.47 40 30 20 10 0-10 -20 degree M. Ferianis ERL 05 Workshop Mario Ferianis TJNAF, October march 20, 2004 2000