22.04.23 Lutz Lilje DESY -MPY-
XFEL Tuner
• Lorentz Force Detuning System Setup• New Saclay design
22.04.23 Lutz Lilje DESY -MPY-
General Remarks• Available today
– Old Saclay Tuner– Simple Single Piezo fixture
• 150-200 Hz compensation • Feedforward works well
– Piezo stacks• Desirable
– Two piezo fixture• Sensor-Actuator configuration
– Future Option: Feedback on sensor piezo?
– Bipolar operation to gain more stroke from Piezo• At cold stroke of piezo is smaller by up to a factor of 10…• … but the material is more forgiving
– New Saclay Tuner
22.04.23 Lutz Lilje DESY -MPY-
General remarks II• Need engineering
– Detailed study on forces at the piezo position• Cold force sensor built by H1• Test in CHECHIA• Design of fixture/frame for 2 piezos
– Selection of best Piezo supplier• Material• INFN works on that
– Control system• Driver Amplifier modification for bipolar operation• Need automated procedures to setup Piezo
– Collaboration with INFN• Detuning measurement
– Preferably in one pulse– Warsaw colleagues are working on this
22.04.23 Lutz Lilje DESY -MPY-
Lorentz Force Detuning System Setup
• Setup description
• Single pulse compensation
• Resonant excitation
• Problems
22.04.23 Lutz Lilje DESY -MPY-
Lorentz Force Detuning System Setup
Function Generator
ADC
PZD Amplifier
Piezo actuator
Piezo sensor
PZM Amplifier
DO
OC
S se
rver
AmplifierLock-in or
Logarithmic
Chechia
MatlabFgen.m
Matlabchread.m
LP filter
22.04.23 Lutz Lilje DESY -MPY-
Piezo Driver Amplifier (PZD)
-45.00
-40.00
-35.00
-30.00
-25.00
-20.00
-15.00
-4.7
0
-4.4
0
-4.1
0
-3.8
0
-3.5
0
-3.2
0
-2.9
0
-2.6
0
-2.3
0
-2.0
0
-1.7
0
-1.4
0
-1.1
0
-0.8
0
-0.5
0
-0.2
0
0.10
0.40
0.70
1.00
1.30
1.60
1.90
2.20
2.50
2.80
input voltage
gain
gain w ith offset
gain w ithout offset
maximum output voltage = -160.9 V
Specification:• Gain of the unloaded amplifier: –38 V/V (0.15),• Output voltage range from -160.9 V to +70 V, (voltage limiter)• Voltage offset: 0,11V• Output voltage rise and fall time: 200s (-160V +60V)• Maximal pulse current 2A (1ms)• Capacitive load 1,5F
22.04.23 Lutz Lilje DESY -MPY-
Piezo Measurement Amplifier (PZM)
Specification:• Gain : 0.5 V/V, (adjustable),• Bandwidth: 100kHz,• Input impedance: 1k,• Output voltage range: ±5V, • Analog output 50 .
22.04.23 Lutz Lilje DESY -MPY-
Piezoelectric tuner IM. Liepe, S. Simrock, W.D.-Moeller
Piezo
He-Tank
& Cavity
Tuning mechanism
Piezo-Actuator:
l=39mm
Umax=150V
l=3m at 2K
fmax,static=500Hz
22.04.23 Lutz Lilje DESY -MPY-
Piezo Tuner setup II• Sensor-Actuator configuration• To compensate for Lorentz force detuning during the 1 ms RF pulse
Feed-Forward• To counteract mechanical noise, “microphonics”
Feed-Back
22.04.23 Lutz Lilje DESY -MPY-
Drawing of current setup (H.-B. Peters)
22.04.23 Lutz Lilje DESY -MPY-
RF signals at 35 MV/m
Blue: With piezo
Red: Without piezo
22.04.23 Lutz Lilje DESY -MPY-
Piezo excitation of the cavity for frequency compensation (operation for 700 hours)
RF pulse (500us fill, 800us flat-top)
22.04.23 Lutz Lilje DESY -MPY-
Single pulse compensation
Pulse Parameters: frequency = 219 Hz time delay = 0.84 ms amplitude = 95V
22.04.23 Lutz Lilje DESY -MPY-
Single pulse compensation
MICROPHONICS
22.04.23 Lutz Lilje DESY -MPY-
Damping of the ringing between pulses (5Hz operation)RF pulse RF pulse RF pulse
22.04.23 Lutz Lilje DESY -MPY-
Frequency stabilization during RF pulse using a
piezoelectric tuner
Blue: With piezo
Red: Without piezo
Frequency detuning of 500 Hz compensated voltage pulse (~100 V) on the piezo. No resonant compensation
22.04.23 Lutz Lilje DESY -MPY-
Option: Resonant excitation of a mechanical cavity resonance
• if one excites a mechanical resonance of a cavity with the piezo, one can use the cavity as an mechanical amplifier, so that a small stroke of the active element can compensate large detuning
• we have shown that with the excitation of three periods of the mechanical resonance frequency, about 1000 Hz could be compensated
22.04.23 Lutz Lilje DESY -MPY-
Resonant excitation (stable for 200 hours)
Pulse Parameters: frequency = 219 Hz time shift = -9.5 ms amplitude = 24V offset = 24V
22.04.23 Lutz Lilje DESY -MPY-
Resonant excitation
22.04.23 Lutz Lilje DESY -MPY-
Frequency stabilization at 35 MV/m
Blue: With piezo
Red: Without piezo
Frequency detuning of ~1000 Hz compensated with resonant excitation of a mechanical cavity resonance at 230 Hz.
NOTE: This is rather an demonstration of the capability of active tuning. Application in a real machine is probably difficult/ impossible. Needs investigation.
22.04.23 Lutz Lilje DESY -MPY-
Module Measurements
22.04.23 Lutz Lilje DESY -MPY-
Single Piezo - Single Pulse Compensation • inside the module • f=200Hz, only 100Hz compensation
22.04.23 Lutz Lilje DESY -MPY-
Single Piezo - Resonant
22.04.23 Lutz Lilje DESY -MPY-
Problems with the active tuner
• Fundamental problem:– Preload at operating temperature not defined– Large tuning needed for both cavities tested in CHECHIA
(AC72, AC73)• ´natural´ frequency after tank welding is 780 kHz above 1,3 GHz• Normally this is more like 200-300 kHz
– This results in a very large force tearing on the piezo fixture
• Fixtures open up and piezos become loose
22.04.23 Lutz Lilje DESY -MPY-
Force Measurement at the Piezo Position
• Design by Karsten Gadow (H1)– Available within 2-3 weeks
• Detailed measurement of the force in the cold environment– Calibration will be first done to liquid
nitrogen temperatures• Then design a fixture with sufficient
stiffness
22.04.23 Lutz Lilje DESY -MPY-
Problems with active tuning• Single Piezo fixture
– So far only 100-200 Hz compensated (no resonant excitation of the cavity)
– Achieved compensation at 1,3 GHz – Alternative: Resonant mechanical excitation of the
cavity• Double Piezo fixture
– Has only been operated at 1,3 GHz + 600kHz– Needs a stiffer design– Alternative: Put 2 single Piezo fixtures at different posts of
the tuner• Bipolar operation of Piezos helps in any case
– Check in CHECHIA and INFN
22.04.23 Lutz Lilje DESY -MPY-
Fixture Twist Problem
Fixture twistsduring operation
22.04.23 Lutz Lilje DESY -MPY-
Problems with active tuning
• Automation is needed for operation of the piezos in the machine– Determination of optimum pulse shape– Interconnection to LLRF system
22.04.23 Lutz Lilje DESY -MPY-
Available piezos (1/2)
• EPCOS
• NOLIAC
• Piezo Mechanik
• Physical Instruments
22.04.23 Lutz Lilje DESY -MPY-
Available piezos (2/2)
Properties Units
EPC
OS
NO
LIA
C
Piez
o M
echa
nik
Phys
ical
In
stru
men
ts
Material name PZT-Nd34 PZT pz27 PZT 5H PZT 25 Young modulus: kN/mm2 51 45 55 35 Cross Section: mm2 7x7 10x10 7,5x7,5 10x10 Length: mm 30 30 55 36 Stroke (RT) µm 40 42 60 30 Resonance frequency kHz 66 14 70
Initial preload No No 400 No Calculated properties:
Stiffness: N/µm 83 150 56 97
Mec
hani
cal
Blocking force kN 3,2 6,3 4,0 3,0 Max voltage V 160 200 150 120 Control speed V/ms 1,6 Charge current A 20 Capacitance (unload) µF 2,1 5,7 13,4 12 (?) Capacitance (850N) µF 3,4 El
ectr
ical
Capacitance @10K µF 1,43
Special features displacement cryogenic
Material parameters yes yes no no
Mec
hani
cal
Elec
trica
l
22.04.23 Lutz Lilje DESY -MPY-
New Saclay Tuner
• Design by P. Bosland• More compact design possible• Cavity should be pre-tuned so that the
tuner is not pushing• Piezo integrated• Available by the end of the year for first
tests
22.04.23 Lutz Lilje DESY -MPY-
New Saclay Tuner 2
22.04.23 Lutz Lilje DESY -MPY-
New Saclay Tuner 3
22.04.23 Lutz Lilje DESY -MPY-
New Saclay Tuner 4
22.04.23 Lutz Lilje DESY -MPY-
Conclusion• Proof-of-principle
– Single-piezo» Non-resonant:100Hz in the module» Resonant: 200 Hz in the module» (We can use this in module 6!)
– Double-piezo» Non-resonant: 400 Hz (not at 1.3GHz exact)» Resonant: 1kHz
– Test of bipolar operation
• Engeneering is needed– Choice of Piezo (-> together with INFN, IPN Orsay))– Stiffer Piezo fixture/frame for 2 Piezos
» Force measurement is underway (finished end 2004?)– LLRF integration
• New Saclay tuner tests needed– Available end 2004 / beginning 2005– Change of cavity pre-tuning desirable