0. CNGS Magnetic Horn & Reflector Oscillation Measurements using the LDV in TCC4
R. Wilfinger, S. Rangod, A. Pardons, K. Elsener, J. Lettry, R. Catherall,
and the CNGS Project Team

1. Laser Doppler Vibrometer (LDV)
Single-Point
Out-of-Plane
Laser Doppler
Vibrometer
from Polytec®,
(Germany)
„Out-of-Plane“
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 1
CNGS Horn & Reflector
Vibration-Measurement in TCC4

2. Laser Doppler Vibrometry
Interferometer
Doppler-Principle
Properties:
-) no mass load on the object of interest
-) contact free (radiation, heat, high tension)
-) measurement parameter:
Doppler shifted frequency (high accuracy, linear!!)
-) distance to target: 0.5 m up to 40 m (verified!)
-) high dynamic range
-) high reproducibility (for long term tests:
fatigue, change of material parameters)
-) displacements measurable even in nm-range!
-) useable for frequencies up to 40 MHz
-) sampling rate: 10 ns
-) for cylindrically shaped surface:
vertical effects can be analyzed
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 2
CNGS Horn & Reflector
Vibration-Measurement in TCC4

3. Vibration-Measurement in TCC4
LDV–Setup in TCC4
Laser points on
mirror and is
reflected to
horn entrance flange
CNGS horn
mirror
on tripod
LDV head
on tripod
LDV head
on tripod
Laser Doppler Vibrometer (LDV)
& CNGS Magnetic Horn in TCC4
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 3
CNGS Horn & Reflector
Vibration-Measurement in TCC4

4. Vibration-Measurement in TCC4
LDV–Setup in TCC4
CNGS target magazine
Horn
entrance
flange
mirror
on tripod
mirror
on tripod
Horn
entrance
flange
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 4
CNGS Horn & Reflector
Vibration-Measurement in TCC4

5. Vibration-Measurement in TCC4
LDV–Setup in TCC4
LDV decoder
& standard PC
outside HV-area
LDV decoder, PC
& ... Stephane ;)
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 5
CNGS Horn & Reflector
Vibration-Measurement in TCC4

6. Vibration-Measurement in TCC4
Horn
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 6
CNGS Horn & Reflector
Vibration-Measurement in TCC4

7. Vibration-Measurement in TCC4
Response of Horn
Displacement / Time Signals
for different pulse gaps
Full damping of the
induced oscillation
within the first second
Speckle drop-out
during measurement:
.) no physical or mechanical
meaning for horn,
.) causes only change of integration
constant in displacement signal
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 7
CNGS Horn & Reflector
Vibration-Measurement in TCC4

8. Response of Horn – Detail 1
Detail of first 100 ms of
displacement / time signals
for different pulse gaps
50 ms pulse gap
causes the
smallest amplitude
after the second
150 kA pulse
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 8
CNGS Horn & Reflector
Vibration-Measurement in TCC4

9. Response of Horn – Detail 2
Detail of 50 ms around the second
150 kA pulse for different pulse gaps
50 ms pulse gap
causes the
smallest amplitude
after the second
150 kA pulse
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 9
CNGS Horn & Reflector
Vibration-Measurement in TCC4

10. Horn Response – after 1 Day Vibration-Measurement in TCC4
Detail of 50 ms around the second
150 kA pulse of displacement / time
signals for 50 ms pulse gap
before and after about 1 day
of pulsing the horn with 150 kA
Identical signals!
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 10
CNGS Horn & Reflector
Vibration-Measurement in TCC4

11. Vibration-Measurement in TCC4
Horn after 1 Day – Detail
Detail of 50 ms around the second
150 kA pulse of displacement / time
signals for 50 ms pulse gap
before and after about 1 day
of pulsing the horn with 150 kA
Identical signals!
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 11
CNGS Horn & Reflector
Vibration-Measurement in TCC4

12. Vibration-Measurement in TCC4
Response of Horn
Comparison
begin and end
of the horn test
.) same damping
.) same oscillation
behavior
Speckle drop-out
during measurement
(no physical meaning
for horn)
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 12
CNGS Horn & Reflector
Vibration-Measurement in TCC4

13. Vibration-Measurement in TCC4
Response of Horn - FFT
FFT spectra of the velocity signal
for different pulse gaps
.) strongest response for
46 and 48 ms pulse gap
.) smallest response
for 50 ms
.) identical peaks for 50 ms
before and after
1 day of pulsing
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 13
CNGS Horn & Reflector
Vibration-Measurement in TCC4

14. Horn Response – FFT – Detail Vibration-Measurement in TCC4
Detail around 148 Hz of
FFT spectra of the velocity signal
for different pulse gaps
.) strongest response for
46 and 48 ms pulse gap
.) smallest response
for 50 ms
.) identical peaks for 50 ms
before and after
1 day of pulsing
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 14
CNGS Horn & Reflector
Vibration-Measurement in TCC4

15. Vibration-Measurement in TCC4
Response of Horn – FFT
.) strongest response for
46 and 48 ms pulse gap
.) smallest response
for 50 ms
.) identical peaks for 50 ms
before and after
1 day of pulsing
High precision
frequency
measurement:
FFT spectra
of the velocity signal
for different pulse gaps
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 15
CNGS Horn & Reflector
Vibration-Measurement in TCC4

16. Vibration-Measurement in TCC4
Response of Horn – FFT
Detail around 148 Hz of
FFT spectra of the velocity signal
for different pulse gaps
.) strongest response for
46 and 48 ms pulse gap
.) smallest response
for 50 ms
.) identical peaks for 50 ms
before and after
1 day of pulsing
High precision
frequency
measurement:
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 16
CNGS Horn & Reflector
Vibration-Measurement in TCC4

17. Vibration-Measurement in TCC4
Response of Horn – FFT
Displacement / Time Signals
for different pulse gaps
Detail around 148 Hz of
FFT spectra of the velocity signal
for 50 ms pulse gap
High precision
frequency measurement:
before and after about 1 day
of pulsing the horn with 150 kA
.) identical peaks
for 50 ms
before and after
1 day of pulsing
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 17
CNGS Horn & Reflector
Vibration-Measurement in TCC4

18. Vibration-Measurement in TCC4
Response of Horn
Displacement / Time Signals
.) Full damping
of the
induced
oscillation
within the
first second
.) Identical
pattern
Velocity / time
signals used
to generate
horn “melody”
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 18
CNGS Horn & Reflector
Vibration-Measurement in TCC4

19. Vibration-Measurement in TCC4
Reflector
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 19
CNGS Horn & Reflector
Vibration-Measurement in TCC4

20. Vibration-Measurement in TCC4
Response of Reflector
Displacement / Time Signals
for different pulse gaps
Full damping of the
induced oscillation
within two seconds
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 20
CNGS Horn & Reflector
Vibration-Measurement in TCC4

21. Vibration-Measurement in TCC4
Response of Reflector
48 ms pulse
gap causes
the smallest
amplitude
after the
second
180 kA pulse.
50 ms pulse
gap causes a
20% increase
for the first
oscillation
after the 2nd
180 kA pulse.
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 21
CNGS Horn & Reflector
Vibration-Measurement in TCC4

22. Vibration-Measurement in TCC4
Response of Reflector
Detail of 50 ms around the second
180 kA pulse for different pulse gaps
~ 20%
identical peaks
for 50 ms
before and after
1 day of pulsing
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 22
CNGS Horn & Reflector
Vibration-Measurement in TCC4

23. Vibration-Measurement in TCC4
Response of Reflector
FFT spectra of the velocity signal
for different pulse gaps
.) strongest response for
52 ms pulse gap
.) smallest response
for 48 ms
.) identical peaks for 50 ms
before and after
1 day of pulsing
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 23
CNGS Horn & Reflector
Vibration-Measurement in TCC4

24. Vibration-Measurement in TCC4
Response of Reflector
Detail around 148 Hz of
FFT spectra of the velocity signal
for different pulse gaps
.) strongest response for
52 ms pulse gap
.) smallest response
for 48 ms
.) identical peaks
(frequency, shape)
for 50 ms
before and after
1 day of pulsing
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 24
CNGS Horn & Reflector
Vibration-Measurement in TCC4

25. Vibration-Measurement in TCC4
Response of Reflector
High precision
frequency measurement:
FFT spectra of the velocity signal
for different pulse gaps
identical peaks in
frequency & shape
for 50 ms
before and after
1 day of pulsing
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 25
CNGS Horn & Reflector
Vibration-Measurement in TCC4

26. Vibration-Measurement in TCC4
Response of Reflector
.) strongest response
for
50 ms pulse gap
because of
velocity spectrum
.) Displacement
proportional to
stress (not velocity)
High precision
frequency measurement:
FFT spectra of the velocity
signal
for different pulse gaps
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 26
CNGS Horn & Reflector
Vibration-Measurement in TCC4

27. Vibration-Measurement in TCC4
Response of Reflector
identical peaks in
frequency & shape
for 50 ms
before and after
1 day of pulsing
High precision
frequency measurement:
FFT spectra of the velocity
signal
for different pulse gaps
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 27
CNGS Horn & Reflector
Vibration-Measurement in TCC4

28. Vibration-Measurement in TCC4
Response of Reflector
Displacement / Time Signals
Velocity / time
signals used
to generate
reflector
“melody”
.) Full damping
of the
induced
oscillation
within the
two seconds
.) Identical
pattern
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 28
CNGS Horn & Reflector
Vibration-Measurement in TCC4

29. Vibration-Measurement in TCC4
Summary: Horn
Full damping of the induced oscillation within the first second.
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 29
CNGS Horn & Reflector
Vibration-Measurement in TCC4

30. Vibration-Measurement in TCC4
Summary: Horn
Full damping of the induced oscillation within the first second.
50 ms pulse gap causes the smallest displacement amplitude after the second 150 kA pulse.
Strongest response for 46 and 48 ms pulse gap.
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 30
CNGS Horn & Reflector
Vibration-Measurement in TCC4

31. Vibration-Measurement in TCC4
Summary: Horn
Full damping of the induced oscillation within the first second.
50 ms pulse gap causes the smallest displacement amplitude after the second 150 kA pulse.
Strongest response for 46 and 48 ms pulse gap.
Identical displacement signals for 50 ms pulse gap before and after about 1 day of pulsing the horn with 150 kA.
Same damping and oscillation behavior before and after about 1 day of pulsing the horn with 150 kA.
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 31
CNGS Horn & Reflector
Vibration-Measurement in TCC4

32. Vibration-Measurement in TCC4
Summary: Horn
Full damping of the induced oscillation within the first second.
50 ms pulse gap causes the smallest displacement amplitude after the second 150 kA pulse.
Strongest response for 46 and 48 ms pulse gap.
Identical displacement signals for 50 ms pulse gap before and after about 1 day of pulsing the horn with 150 kA.
Same damping and oscillation behavior before and after about 1 day of pulsing the horn with 150 kA.
Identical FFT-peaks (frequency & shape) for 50 ms before and after
1 day of pulsing.
Identical oscillation pattern (amplitude & damping) for different pulses in a sequence.
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 32
CNGS Horn & Reflector
Vibration-Measurement in TCC4

33. Vibration-Measurement in TCC4
Summary: Reflector
Full damping of the induced oscillation within the two seconds.
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 33
CNGS Horn & Reflector
Vibration-Measurement in TCC4

34. Vibration-Measurement in TCC4
Summary: Reflector
Full damping of the induced oscillation within the two seconds.
50 ms pulse gap causes a 20% increase of the first oscillations after the 2nd 180 kA pulse.
Identical displacement signals for 50 ms pulse gap before and after about 1 day of pulsing the horn with 180 kA.
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 34
CNGS Horn & Reflector
Vibration-Measurement in TCC4

35. Vibration-Measurement in TCC4
Summary: Reflector
Full damping of the induced oscillation within the two seconds.
50 ms pulse gap causes a 20% increase of the first oscillations after the 2nd 180 kA pulse.
Identical displacement signals for 50 ms pulse gap before and after about 1 day of pulsing the horn with 180 kA.
48 ms pulse gap causes the smallest displacement amplitude after the second 180 kA pulse.
Strongest response for 52 ms pulse gap.
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 35
CNGS Horn & Reflector
Vibration-Measurement in TCC4

36. Vibration-Measurement in TCC4
Summary: Reflector
Full damping of the induced oscillation within the two seconds.
50 ms pulse gap causes a 20% increase of the first oscillations after the 2nd 180 kA pulse.
Identical displacement signals for 50 ms pulse gap before and after about 1 day of pulsing the horn with 180 kA.
48 ms pulse gap causes the smallest displacement amplitude after the second 180 kA pulse.
Strongest response for 52 ms pulse gap.
Same damping and oscillation behavior before and after about 1 day of pulsing the horn with 180 kA.
Identical FFT-peaks (frequency & shape) for 50 ms before and after
1 day of pulsing.
Identical oscillation pattern (amplitude & damping) for different pulses in a sequence.
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 36
CNGS Horn & Reflector
Vibration-Measurement in TCC4

37. Vibration-Measurement in TCC4
Conclusion
Horn displacement response is minimized for a pulse gap of 50 ms.
50 ms pulse gap for the reflector causes a 20% increase of the first oscillations after the 2nd 180 kA pulse.
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 37
CNGS Horn & Reflector
Vibration-Measurement in TCC4

38. Vibration-Measurement in TCC4
Conclusion
Horn displacement response is minimized for a pulse gap of 50 ms.
50 ms pulse gap for the reflector causes a 20% increase of the first oscillations after the 2nd 180 kA pulse.
Horn is more sensitive to oscillation propterties,
.) since it is less rigid compared to the reflector
.) and closer to the target magazine
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 38
CNGS Horn & Reflector
Vibration-Measurement in TCC4

39. Conclusion Horn and reflector can be pulsed with 50 ms.
Horn displacement response is minimized for a pulse gap of 50 ms.
50 ms pulse gap for the reflector causes a 20% increase of the first oscillations after the 2nd 180 kA pulse.
Horn is more sensitive to oscillation propterties,
.) since it is less rigid compared to the reflector
.) and closer to the target magazine
Horn and reflector can be pulsed with 50 ms.
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 39
CNGS Horn & Reflector
Vibration-Measurement in TCC4

40. Conclusion Thanks for your attention!!!
Horn displacement response is minimized for a pulse gap of 50 ms.
50 ms pulse gap for the reflector causes a 20% increase of the first oscillations after the 2nd 180 kA pulse.
Horn is more sensitive to oscillation propterties,
.) since it is less rigid compared to the reflector
.) and closer to the target magazine
Horn and reflector can be pulsed with 50 ms.
Thanks for your attention!!!
NBI–2006 Workshop, CERN,
Sept. 06th, 2006, Page 40
CNGS Horn & Reflector
Vibration-Measurement in TCC4