WP8.1 UMI Tuner A. Bosotti, N. Panzeri, R. Paparella, F. Puricelli Updates since the last CARE meeting: Life Time Test for PI-P Cryogenic calibration of a new force sensor CELMI Progress on the Blade Tuner (presented by Nicola Panzeri)

Piezo Life-Time Test 1/2 PROPERTIESPI P Unit MaterialPZT-PIC 255 Length36mm Cross section100mm 2 Max. stroke35μm Blocking force3600N Res. no load40kHz Min. voltage-20V Max. voltage120V Capacity - nominal12,4μF Capacity - measured13,6μF 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 PIC255 piezoelectric ceramic has been cooled down in LN2 and has been excited uninterruptedly for a month up to its limits, sustaining about 1.5x10 9 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 diagramInsert “functional” scheme

BeforeAfter Capacity [uF] Res. Freq [kHz] Max stroke [um] Piezo Life-Time Test 2/2 Start26 Nov 2004 Stop20 Dec 2004 Hours622 Cycles1.505x10 9 Sine Wave Amplitude-20V ÷ +120 V Frequency 117 Hz for 4 days 497 Hz for 6 days 997 Hz for 16 days Average Preload1.25 kN Max Current [rms]< 200 mA Average Temperature81 K Main features of the life time test Hysteresis loops comparisons Solartron SM1 LVDT position transducer  = 149 mV/V/mm Main piezo parameters checked

Cryogenic calibration of a new force sensor CELMI /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. Results: Unacceptable 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

Cryogenic calibration of a new force sensor CELMI /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 = mbar DUT T ranging from 6 to 15 K > 4000 calibration points 5 full range load sweeps, kg

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

Conclusions After about one month of operation in LN2 environment under extreme conditions, and after more than 1.5x10 9 oscillations driven between (nominal) operating voltage limits, the PI P 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.