LCLS RF Stability Requirements LCLS Requirements The SLAC

LCLS RF Stability Requirements LCLS Requirements The SLAC Linac Stability Data SPPS Measurements LCLS RF System October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

LCLS INJECTOR / LINAC P. Emma October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

LCLS Machine Stability Tolerance Budget Lowest Noise Floor Requirement 0. 5 deg X-Band = 125 f. S Structure Fill time = 100 n. S Noise floor = -108 d. Bc/Hz @ 11 GHz 5 MHz BW -134 d. Bc/Hz @ 476 MHz 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 L 2 and L 3 are Nk larger, assuming uncorrelated errors, where Nk is the number of klystrons per linac. P. Emma October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

LINAC RF and Timing System LCLS must be compatible with the existing linac operation including PEP timing shifts Master Oscillator is located 1. 3 miles from LCLS Injector PEP PHASE SHIFT ON MAIN DRIVE LINE October 12, 2004 LCLS FAC Review RF, Timing 1. 3 Miles to LCLS Injector MDL RF with TIMING Pulse – Sync to DR R. Akre akre@slac. stanford. edu

SLAC Linac RF The PAD measures phase noise between the reference RF and the high power system. The beam sees 3. 5 u. S of RF from SLED cavity which the klystron fills and is then dumped into the accelerator structure. October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

LINAC RF MEETS ALL LCLS SPECIFICATIONS for 2 Seconds when running well Amplitude fast time plots show pulse to pulse variation at 30 Hz. Standard deviation in percent of average amplitude over 2 seconds are 0. 026% for 22 -6 and 0. 036% for 22 -7. October 12, 2004 LCLS FAC Review RF, Timing Phase fast time plots show pulse to pulse variation at 30 Hz. Standard deviation in degrees of 2856 MHz over 2 seconds for the three stations are 0. 037 for 22 -6 and 0. 057 for 22 -7. R. Akre akre@slac. stanford. edu

LINAC RF is Out of LCLS Specs in 1 Minute Amplitude Phase 22 -6 0. 20%pp 1. 2 Deg pp Amplitude Phase 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 They also track the temperature of the water system October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

Linac Phase Reference System Main Drive Line - 3 1/8 Rigid Coax Anchored to Concrete Floor Every Sector Phase Reference Line - Each Sector Independent ½ inch Heliax MDL 200 f. S rms / Sector PRL 640 f. S rms October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

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 (2 QL T), Where T = L/L = - / QL= 17000 = 10 -5 / F Thermal expansion of copper. -1 =tan (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. 50 800 n. S 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 -5 = -10 T / F 2 2856 MHz 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] October 12, 2004 LCLS FAC Review RF, Timing Info from D. Farkas Info from P. Wilson R. Akre akre@slac. stanford. edu

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 October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

Linac Phase Stability Estimate Based on Energy Jitter in the Chicane BPM 1 Ge. V 9 Ge. V SLAC Linac 30 Ge. V s. E/E 0 0. 06% e- Energy (Me. V) Df 2 1/2 < 0. 1 deg (100 fs) October 12, 2004 LCLS FAC Review RF, Timing P. Emma R. Akre akre@slac. stanford. edu

Electro-Optical Sampling 200 m thick Zn. Te crystal Single-Shot e- <300 fs Ti: Sapphire laser e- temporal information is encoded on transverse profile of laser beam 170 fs rms LASER to BEAM Jitter Adrian Cavalieri et al. , U. Mich. October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu Timing Jitter (20 Shots)

SPPS Laser Phase Jump Tracking R. Akre, A. Cavalieri October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

SPPS Laser Phase Jump Tracking ~ 200 u. S Laser Phase Error – Output Phase to Input Reference - Modulated with 1 Hz Square Wave 0. 25 p. S pk Square Wave October 12, 2004 LCLS FAC Review RF, Timing 2. 0 p. S pk Square Wave R. Akre akre@slac. stanford. edu

SPPS Laser Amplitude of Phase Transfer Function 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 12 d. B to prevent laser from unlocking. Data taken 10/22/03 October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

LCLS Phase Noise Associated Time Referenced to Beam Time LCLS Laser LCLS Gun SLED / Accelerator Phase Detector (Existing) Distribution System ~200 u. S Off Scale Below 1. 1 u. S Except for the LASER 3. 5 u. S common mode noise 30 n. S levels below ~100 k. Hz 200 n. S would not cause 1 km @ c-97%c=100 n. S Far Hall Trigger 3 km @ c-80%c=2 u. S -3. 5 us SLED Starts to Fill -2 u. S Far Hall Trig RF Starts Trip 2 u. S instabilities – the entire system would track the deviations -1. 1 u. S Gun Starts to Fill Beam Time 0 Reference TIME October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

RF Distribution Phase Noise New Master Oscillator in Linac Front End Less than 25 f. S rms jitter in Bandwidth from 38 Hz to 5 MHz R. Akre, K. Schaffold October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

RF Distribution Phase Noise Integrated Noise - Timing Jitter fs rms Integral end Integral start Master Osc. PEP Phase Master Amp MDL Sector 30 - 2 miles 5 MHz 1 M 18 22 48 48 54 100 k 20 26 54 56 60 10 k 20 34 62 62 66 1 k 20 36 74 74 76 10 k. Hz 100 10 120 136 144 150 10 16 120 144 152 164 Need to lower phase noise in PEP Phase Shifter and Master Amplifier October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

LINAC SECTOR 20 – LCLS INJECTOR RF Stability < 50 f. S rms : Timing/Trigger Stability 30 p. S rms Using LASER as LCLS RF OSCILLATOR is UNDER CONCIDERATION October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

LCLS RF System – Sector 20 Layout 100 ft ½” Heliax = 0. 3ºS/ºF Tunnel Temperature < 0. 1 deg F rms October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

Beam Trigger for User Facility Single Pulse with 30 f. S stability (1 Hz to 3 GHz BW) Tightest Noise Tolerance of LCLS Wide Bandwidth Low Phase Noise 30 f. S Stability today 10 f. S Stability tomorrow 1 f. S The Day After Currently users are expected to use local beam timing measurement, EO, to achieve this. October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

LCLS RF System Injector RF – FY 06 Upgrade of existing system / Lower Noise Timing requirements Injector/L 1 Phase Reference System Phase and Amplitude measurement system Solid State Sub-Boosters Beam Phase Monitor System X-Band RF system – FY 06 Linac Phase Reference System – FY 07 Linac Feedback Control – FY 07 Feedback Development – FY 07 Far Hall Trigger – FY 08 October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

Near Term (6 Month) Tasks Measure Phase Noise of SPPS Laser Lower phase noise in PEP phase shifter and Master Amplifiers Determine Type of RF Phase and Amplitude Measurement System October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu

FY 05/06 Tasks and Resources Ready to Ramp Up Start on X-Band system Complete SLAC Linac Front End Upgrades Complete Design of Phase Reference System Complete Design of LLRF Control System Define Beam Phase Cavity Monitor Further Studies on Linac Stability SLAC Klystron Department to Support 75% of RF manpower Manpower available from other SLAC groups (ARDA, ARDB, NLC, and Controls) and LBNL October 12, 2004 LCLS FAC Review RF, Timing R. Akre akre@slac. stanford. edu