DESY MHF-p 1 Layout of the Synchronisation System for the VUV-FEL Dipl. Ing. Henning Christof Weddig DESY Hamburg

DESY MHF-p 2 RF System Requirements System Length200 m (VUV_FEL); 3 km (XFEL) RF Phase Noise (within macropulse – 1 ms) 0.05 o RMS (at 1.3 GHz)  ~0.1 ps RF Phase Noise (during 100 ms time) 0.15 o RMS (at 1.3 GHz)  ~0.3 ps RF Phase Stability (short term <1 minute) <0.5 o (at 1.3 GHz)  ~1 ps RF Phase Stability (long term) <5 o (at 1.3 GHz)  ~10 ps RF frequency range 1 MHz – 2.8 GHz

DESY MHF-p 3 System components Ultra high stable master oscillator RF distribution system (length at VUV-FEL about. 200 m) Temperature stabilized coaxial cables Local 1.3 GHz/2.856 GHz frequency generation Fiber optic and coaxial system to monitor and correct long term phase drifts

DESY MHF-p 4 Frequencies to be distributed the exact frequencies are multiples or divisions of the MHz reference frequency 1 MHz (timing of complete machine) 9 MHz (master reference frequency) 13.5 MHz (Laser “new”) 27 MHz(Laser “old”) 54 MHz(Laser for future use) 81 MHz(distribution frequency) 108 MHz(Streak camera [near RF Gun; Experimental Hall]) 1300 MHz(reference frequency for the linear collider) 1517 MHz(reference frequency for beam position monitors) 2856 MHz(“LOLA” = transverse deflecting cavity for bunch measurements)

DESY MHF-p 5 Block diagramme of MO (low level part)

DESY MHF-p 6 Phase noise requirements for the 1.3 GHz reference frequency

DESY MHF-p 7 Phase noise performance of a 27 MHz crystal oscillator

DESY MHF-p 8 Phase noise performance of a 81 MHz crystal oscillator Phase noise is better above  400 Hz from carrier!

DESY MHF-p 9 MO front panel (low level part)

DESY MHF-p 10 Layout of the Reference frequency distribution system for TTF2

DESY MHF-p 11 The problem of long coaxial distribution links: Attenuation of coaxial cable vs frequency

DESY MHF-p 12 Phase stability of coaxial cable vs. Temperature ½ ´´ cable

DESY MHF-p 13 Phase stability of coaxial cable vs. Temperature 7/8 ´´ cable

DESY MHF-p 14 Advantages and disadvantages of coaxial cables Coaxial cables for distribution: - high attenuation (e.g. 1.3GHz A / 100m = 8dB) - physical dimensions - require temperature stabilization - can cause ground loops and pick up EMI Fiber Optics for monitoring : - require active temperature stabilization - the system components are more expensive in comparison to coaxial line system components - high amplitude noise of a FO link Solution: A combination of both technologies will be implemented and studied at TTF2.

DESY MHF-p 15 Fiber optic distribution scheme

DESY MHF-p 16 First results of fiber optic stabilization