R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 LCLS RF Stability Requirements LCLS Requirements The SLAC Linac SLAC Linac Stability Data SPPS Measurements LCLS RF System

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 LCLS INJECTOR / LINAC

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 LCLS Machine Stability Tolerance Budget X-band X-X-X-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 LCLS April 29, 2004 LINAC RF and Timing System PEP PHASE SHIFT ON MAIN DRIVE LINEMDL RF with TIMING Pulse – Sync to DR Master Oscillator is located 1.3 miles from LCLS Injector 1.3 Miles to LCLS Injector

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 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

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 Linac Phase Reference System Main Drive Line 3 1/8 inch Rigid Coax with 30watts Length = 31 Sectors, 15.5 furlongs 2miles, 3km : Velocity = 0.98c Anchored at each sector next to coupler and expansion joint Purged with dry nitrogen Phase Length Range 100  S/Year Phase Length Range 40  S/Day Accuracy Based on SLC Fudge Factor 0.5  S/Sector Total Variation 0.2  S rms / Sector Phase Reference Line ½ inch Heliax Cable with 1.2 Watts Phase Reference for 8 PADs (Klystrons) in the sector Length = 1 Sector, 0.5 furlongs, 332ft, 400k  S in ½” Heliax Temperature Coefficient 4ppm/  C Waveguide Water  T = 0.1  C rms 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

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 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.

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 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 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  for 22-6 and  for 22-7.

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 LINAC RF is Out of LCLS Specs in 1 Minute 14 minutes data taken using the SCP correlation plot Note that 22-6 and 22-7 are correlated in phase and amplitude Amplitude %pp Amplitude %pp Phase Deg pp Phase Deg pp

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 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 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

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 Linac Phase Stability Estimate Based on Energy Jitter in the Chicane SLAC Linac 1 GeV 30 GeV 30 GeV 9 GeV e  Energy (MeV) BPM  2  1/2  < 0.1 deg (100 fs)  E /E 0  0.06%

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 LCLS Phase Noise Associated Time Referenced to Beam Time LCLS LaserNeed to Measure 10uS to 1mS LCLS Gun1.1uS SLED / Accelerator 3.5uS Phase Detector (Existing)30nS Distribution System200nS c-97%c=100nS Far Hall Trigger2uS c-80%c=2uS TIME -3.5us SLED Starts to Fill -1.1uS Gun Starts to Fill -2uS Far Hall Trig RF Starts Trip Beam Time 0 Reference

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 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 476MHz 11fS rms Jitter in 5MHz BW or 31fS rms Jitter in 40MHz BW

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 SPPS Laser Phase Noise Measurements Phase Noise of Output of Oscillator with Respect to Input Measurement done at 2856MHz with External Diode

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 Jitter determination from Electro Optic sampling ErEr Principal of temporal-spatial correlation Line image camera polarizer analyzer EO xtal  seconds, 300 pulses:  z = 530 fs ± 56 fs rms  t = 300 fs rms single pulse A. Cavalieri centroid width

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 LINAC SECTOR 20 – LCLS INJECTOR RF Stability < 50fS rms : Timing/Trigger Stability 30pS rms

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 LCLS RF System – Sector 20 Layout 100ft ½” Heliax = 0.3ºS/ºF

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 Beam Trigger for User Facility Wide Bandwidth – Rising Edge of 8nS ? Low Phase Noise – 30fS Stability Design Needs Input

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 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

R. Akre, P. Emma, P. Krejcik LCLS April 29, 2004 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