DESY MHF-p1

Layout of the Synchronisation Layout of the Synchronisation System for the VUV-FELSystem for the VUV-FEL

Dipl. Ing. Henning Christof WeddigDESY Hamburg

DESY MHF-p2

RF System RequirementsRF System Requirements  System Length 200 m (VUV_FEL); 3 km (XFEL)RF Phase Noise (within macropulse – 1 ms)

0.05o RMS (at 1.3 GHz) ~0.1 psRF Phase Noise (during 100 ms time)

0.15o RMS (at 1.3 GHz) ~0.3 psRF Phase Stability (short term <1 minute)

<0.5o (at 1.3 GHz) ~1 psRF Phase Stability (long term)

<5o (at 1.3 GHz) ~10 psRF frequency range

1 MHz – 2.8 GHz

DESY MHF-p3

System componentsSystem 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-p4

Frequencies to be distributedFrequencies to be distributed 

the exact frequencies are multiples or divisions of the 9.027775 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-p5

Block diagramme of MO (low level part)Block diagramme of MO (low level part)

DESY MHF-p6

Phase noise requirements for the 1.3 GHz Phase noise requirements for the 1.3 GHz reference frequencyreference frequency

Phase noise limit line 1.3 GHz Reference Oszillator

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

1 10 100 1000 10000 100000 1000000

offset from carrier frequency (Hz)

Ph

as

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ois

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c/H

z)

limit line

Integral = -90 dBc =0.00003 rad= 3 fs @ 1.3 GHz

Integral = -100 dBc= 0.00001 rad= 1 fs @ 1.3 GHz

Integral = - 95 dBc= 0.0000316 rad= 3 fs @ 1.3 GHz

Integral = -85 dBc= 0.00316 fs= 30 fs @ 1.3 GHz

Integral = -50 dBc= 0.003 rad366 fs @ 1.3 GHz

1RF cycle @ 1.3 GHz = 768 ps1 rad = 122 ps

overall phase jitter (double side band):2 * SQRT (366 2̂ + 30 2̂ + 3 2̂ + 1 2̂ + 3 2̂) = 2 * 367 fs = 734 fs = 0.7 ps

DESY MHF-p7

Phase noise performance of a Phase noise performance of a 27 MHz crystal oscillator27 MHz crystal oscillator

 

DESY MHF-p8

Phase noise performance of a Phase noise performance of a 81 MHz crystal oscillator81 MHz crystal oscillator

 

Phase noise is better above 400 Hz from carrier!

DESY MHF-p9

MO front panelMO front panel(low level part)(low level part)

 

DESY MHF-p10

Layout of the Reference frequency distribution system for TTF2Layout of the Reference frequency distribution system for TTF2

DESY MHF-p11

The problem of long coaxial distribution links:The problem of long coaxial distribution links:Attenuation of coaxial cable vs frequencyAttenuation of coaxial cable vs frequency

DESY MHF-p12

Phase stability of coaxial cable vs. TemperaturePhase stability of coaxial cable vs. Temperature½ ´´ cable½ ´´ cable

DESY MHF-p13

Phase stability of coaxial cable vs. TemperaturePhase stability of coaxial cable vs. Temperature7/8 ´´ cable7/8 ´´ cable

DESY MHF-p14

Advantages and disadvantages of coaxial cablesAdvantages and disadvantages of coaxial cablesCoaxial cables for distribution:

- high attenuation (e.g. 7/8“ @ 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-p15

Fiber optic distribution schemeFiber optic distribution scheme

Circulator Long Link Mirror

RF PhaseDetector

DFBLaserFO Tx

Phase stable RFSignal

FO RxC

DirectionalCoupler

FO RxA

Phase Shifter

Controller

DirectionalCoupler

FO RxB

RFSignal in

5 kmsingle mode fiber

in temperaturecontrolled ovenoptional

DESY MHF-p16

First results of fiber optic stabilization First results of fiber optic stabilization

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