WP8.1 UMI Tuner A. Bosotti, N. Panzeri, R. Paparella, F. Puricelli

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WP8.1 UMI TunerA. Bosotti, N. Panzeri, R.
Paparella, F. Puricelli

• Updates since the last CARE meeting
• Life Time Test for PI-P889.90
• Cryogenic calibration of a new force sensor
  CELMI 142-500
• Progress on the Blade Tuner (presented by Nicola
  Panzeri)

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Piezo Life-Time Test 1/2
PROPERTIES PI P-888.90 Unit
Material PZT-PIC 255  
Length 36 mm
Cross section 100 mm2
Max. stroke 35 µm
Blocking force 3600 N
Res. frequency _at_ no load 40 kHz
Min. voltage -20 V
Max. voltage 120 V
Capacity - nominal 12,4 µF
Capacity - measured 13,6 µF
The purpose of this test is to investigate the
behavior of piezoelectric ceramics in condition
equivalent to 10 years of operation as actuator
in active frequency tuner for ILC superconducting
cavities (SC). To do this a Physik Instrumente
PI P-888.90 PIC255 piezoelectric ceramic has been
cooled down in LN2 and has been excited
uninterruptedly for a month up to its limits,
sustaining about 1.5x109 cycles of switching, up
to nearly the maximum stroke, a good estimate of
ten years as actuator for ILC cavities.
Main features and parameters of the piezo
Experimental apparatus block diagram
Insert functional scheme
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Piezo Life-Time Test 2/2
Start 26 Nov 2004
Stop 20 Dec 2004
Hours 622
Cycles 1.505x109
Sine Wave Amplitude -20V 120 V
Frequency 117 Hz for 4 days 497 Hz for 6 days 997 Hz for 16 days
Average Preload 1.25 kN
Max Current rms lt 200 mA
Average Temperature 81 K
Before After
Capacity uF 13.6 13.56
Res. Freq kHz 45.9 45.2
Max stroke um 40.2 38.3
Main piezo parameters checked
Main features of the life time test
Sensitivity _at_20kHz s 149 mV/V/mm
Hysteresis loops comparisons
Solartron SM1 LVDT position transducer
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Cryogenic calibration of a new force sensor
CELMI 142-500 1/3
Previous measurements have showed an unacceptable
behavior of standard load cells when operated in
a cryogenic environment.

• Main problems were
• Glue plastic deformations appears at low
  temperature.
• Strain Gauge high virtual load, high
  hysteresis.

ResultsUnacceptable lack of stability,
uniformity and repeatability in the response
As a consequence a custom load cell, manufactured
by CELMI srl (Buccinasco, Italy), has been
realized and tested in order to verify the
performances of cryogenic-devoted sensitive
elements (strain gauge glue)

• Main features
• Standard steel case (model 142), high
  transverse load resistance
• Strain gauge and glue suitable for cryogenic
  applications

CELMI load cell mod.142-500
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Cryogenic calibration of a new force sensor
CELMI 142-500 - 2/3
The setup developed for previous load cell test
has been used
A stable liquid He T has not been reached because
of the high heat transfer through the steel rod
that exerts the force

• P 1.4 10-3 mbar
• DUT T ranging from 6 to 15 K
• gt 4000 calibration points
• 5 full range load sweeps, 0-200 kg

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Cryogenic calibration of a new force sensor
CELMI 142-500 - 3/3
This new sensor can be calibrated with an
acceptable error, the trend can be assumed to be
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Conclusions

• After about one month of operation in LN2
  environment under extreme conditions, and after
  more than 1.5x109 oscillations driven between
  (nominal) operating voltage limits, the PI P
  888.90 piezo is still working with almost the
  same characteristics.
• The test on CELMI prototype has proved that the
  glue and strain gauge sensors used can work in
  LHe cryogenic environment with good repeatability
  and sensitivity.
• Future developments
• Realization of a new cell hosting the same
  sensitive elements but with the proper shape and
  reduced dimensions
• Testing and calibration of the new cell with a
  more accurate DUT thermal stability - some
  solutions, already adopted for piezo tests, has
  been discarded due to the CELMI prototype size.
• A new insert to perform more accurate tests on
  piezos and force sensors has been designed and is
  under construction.