XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Lutz Lilje, DESY, TILC08 Tests with the Fast Frequency Tuners in the Saclay-I design Lutz

XFELThe EuropeanX-Ray Laser Project X-Ray Free-Electron Laser

Lutz Lilje, DESY, TILC08

Tests with the Fast Frequency Tuners in the Saclay-I design

Lutz Lilje

DESY

Lutz Lilje, DESY, TILC08يح


Acknowledgements

– Thanks for– … the participation and support in the

experiments• R. Paparella, K. Przygoda

– … to many people supporting these experiments

• C. Albrecht, O. Keller, C. Müller, T. Fröhlich, R. Lange, T. Bruns, W. Koprek, W. Jalmuzna, A. Brandt, D. Kostin



Motivation

– It is clear that the current version of this tuner does not fit mechanically.

– Nonetheless, the tuner tests ILC concepts• Standard TESLA cavity design (and short ILC design)

– Stiffening concept

• Motor– Cold location

• Piezo– Cold location



Overview

– Tuner system• Saclay design with added piezo tuner

– Measurements on Modules• Classical Pretuning of the cavity

– Cavity pushes back on the tuner» Difficult to adjust pre-load on the cavity

• Double-Piezo fixture– M6, (M8)

• Single-Piezo fixture– M5, M7

– CHECHIA Measurements• Reversed Pretuning of the cavities

– Cavity pulls on tuner



Tuner Setup

– Current design in use at FLASH• Design by CEA

• Fast piezo detuning introduced not from beginning

• Is the solution for XFEL so far

Design by M. Maurier and P. Leconte based of the MACSE tuner design (CEA

Saclay)

Lscrew

LarmsLcavity



Tuner System Features

– Well-known– Piezo integration not straight-forward

• Piezo fixture stiff enough for pre-detuning of roughly +300 KHz

– Beyond this piezo operation cannot be guaranteed

– Therefore reverse pre-tuning (-200 kHz) of cavities has ben tried in CHECHIA tests

• Successful

– M8 is fully equipped with this type of piezos• Test this year



Module 6 Double-Piezo Tests

– Initial demonstration for each cavity• Measure detuning• Compensate detuning individually, one after the other

– Classical compensation

– ´Second oscillation´ compensation

– No RF feedback

• In addition– Work on piezo diagnostics: Impedance measurement

– Measure transfer functions from one piezo to another

– Demonstrate compensation on full module for all cavities simultaneously

• With RF feedback



Lorentz Force Detunings in Module 6

0

100

200

300

400

500

600

700

800

0 5 10 15 20 25 30 35 40

Eacc[MV/m]

Det

un

ing

ove

r F

lat-

To

p [

Hz]

C1C2C3C4C5C6C7C8



Example: Cavity 3

Lorentz Force Detuning

0

100

200

300

400

500

600

700

800

0 5 10 15 20 25 30 35 40

Cavity Gradient [MV/m]

Lore

ntz

Forc

e de

tuni

ng [H

z]



Cavity 3: Gradient

35 MV/m



Cavity 3: Phase



Cavity 3: Detuning



Compensated Detuning per Cavity

Maximum Lorentz Force detuning compensation results

0

100

200

300

400

500

600

700

cav 1 - 35 MV/m cav 2 - 31 MV/m cav 3 - 35 MV/m cav 4 - 33 MV/m cav 6 - 20 MV/m cav 7 - 30 MV/m cav 8 - 23 MV/m

Det

unin

g ov

er th

e fla

t-top

[Hz]

Piezo OFF

Piezo ON



Voltage on Piezo Needed for CompensationCompensated Detuning vs. Applied Piezo Voltage

half-sine pulse, 2.5 ms width and 0.6 to 0.64 ms advance from RF pulse

y = 7,594x

R2 = 0,98

0

100

200

300

400

500

600

700

0 10 20 30 40 50 60 70 80 90 100

Piezo Voltage [V]

Com

pens

ated

det

unin

g [H

z]

CAV 3

Linear (CAV 3)

– Piezo Voltages within margin• maximum PI piezo voltage of 120 V at room temperature• Could also use bipolar operation, but not needed



Compensated Detuning vs. Delay to RF@25 MV/m

Normalized detuning over the flat-top for vs. piezo pulse delay

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

2,0

-7 -6 -5 -4 -3 -2 -1 0 1 2Piezo pulse start time [ms]

No

rma

lize

d a

mp

litu

de

Delay analysison cavity 1




2nd osc.compensationresults1st osc.compensationresults

RF pulse



Pre-Detuning Change Due to Piezo Pulse Delay when using the ‚second oscillation‘

– Can change the cavity pre-detuning of the cavity by changing the Piezo delay to use the ‘second oscillation‘ in the order of 200Hz

• Less motor usage, increase lifetime• Correponds to He drifts of a few mbar

Cavity 4



Full Module Tests

– Three modules tested with piezos• M5, M6, M7

– At least one module will be done this year• M8• M3 repair (after crash test) to be decided

– Simultaneous operation of several piezos with the same drive signal possible

• Only 2 function generators (FG) available• E.g. 4 cavities on one FG with amplifier and 2 cavities on the other FG

with second amplifier for M6



0 200 400 600 800 1000 1200 14005

5.1

5.2

5.3

5.4

5.5

5.6

5.7

5.8

5.9

6

Time [us]

Am

plitu

de [A

.U.]

Vector Sum of Module 6 with and without piezo active compensationRF feedback ON, same control-loop-gain setting

0 200 400 600 800 1000 1200 140018

18.5

19

19.5

20

20.5

21

21.5

22

Time [us]

Pha

se [d

eg]

Piezo compensation OFFPiezo compensation ON

Operation of Full module – Vector-Sum



Operation of Full Module – Forward Power

0 500 1000 1500 20000

50

100

150

200

250

300

350

Time [us]

For

war

d po

wer

am

p. [

kW]

0 500 1000 1500 20000

50

100

150

200

250

300

350

Time [us]

For

war

d po

wer

am

p. [

kW]

0 500 1000 1500 20000

50

100

150

200

250

300

350

Time [us]

For

war

d po

wer

am

p. [

kW]

RF feedback switched ON on module 6 in CMTB. Collection of all amplitude of forward power signals with and without piezo active compensation

0 500 1000 1500 20000

50

100

150

200

250

300

350

Time [us]

For

war

d po

wer

am

p. [

kW]

0 500 1000 1500 20000

20

40

60

80

100

120

140

Time [us]

For

war

d po

wer

am

p. [

kW]

0 500 1000 1500 20000

50

100

150

Time [us]

For

war

d po

wer

am

p. [

kW]

0 500 1000 1500 20000

50

100

150

200

250

Time [us]

For

war

d po

wer

am

p. [

kW]

0 500 1000 1500 20000

50

100

150

200

Time [us]

For

war

d po

wer

am

p. [

kW]

Piezo compensation OFF

Piezo compensation ON



500 1000 1500 2000-400

-300

-200

-100

0

100

200

300

400

Time [us]

Det

unin

g [H

z]

500 1000 1500 2000-400

-300

-200

-100

0

100

200

300

400

Time [us]

Det

unin

g [H

z]

500 1000 1500 2000-400

-300

-200

-100

0

100

200

300

400

Time [us]

Det

unin

g [H

z]

Detuning of all cavities of Module 6 with and without piezo active compensation

500 1000 1500 2000-400

-300

-200

-100

0

100

200

300

400

Time [us]

Det

unin

g [H

z]

Cavity 1,2,3,4 : signal 1 - half sin 2.5 ms width, 60 V, 640 us advance

500 1000 1500 2000-400

-300

-200

-100

0

100

200

300

400

Time [us]

Det

unin

g [H

z]

500 1000 1500 2000-400

-300

-200

-100

0

100

200

300

400

Time [us]

Det

unin

g [H

z]

Cavity 5,6 : no signal - no active compensation

500 1000 1500 2000-400

-300

-200

-100

0

100

200

300

400

Time [us]

Det

unin

g [H

z]

500 1000 1500 2000-400

-300

-200

-100

0

100

200

300

400

Time [us]

Det

unin

g [H

z]

Cavity 7,8 : signal 2 - half sin 2.5 ms width, 64 V, 640 us advance



M5: Piezos off



M5: Piezos on



Tests with New Pre-tuning

– E.g. Z107 at 35 MV/m

– Piezo settings• Simple pulse• Frequency: 400

Hz• Voltage: 2.4 V

(roughly 100 V)• Offset: -0.4• Advance to RF

signal:0.8511 ms



Next for this type of tuner

– Industrialisation for XFEL• Drive units

– Full-drive units from Industry– This year

• Mechanics– Involvement of Mass-production companies– This year

– Series production in 2009



Conclusion and Outlook

– Several aspects of relevance for ILC• Concept• Choice of active elements• Industrialization

– Piezo as actuators• Endurance operation in TTF will start this year

– Endurance tests in test stands have been done already– Successful compensation of detuning on full modules simultaneously

• TESLA cavities are stiff enough

– ´Second oscillation´ compensation could reduce number of steps on the motors as delay of Piezo could be used to compensate for small frequency drifts

• Relaxes reliability requirements on motors

– Industrialization of the full tuner system is on the way for XFEL

Documents

XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Lutz Lilje, DESY, TILC08 Tests with the Fast Frequency Tuners in the Saclay-I design Lutz