The deposition processes of PZT thin ®lms have been described in many reports, yet there have been no descriptions of the performance of PZT ®lms at high intensity operation. Hydrothermally-deposited PZT ®lm transducers were examined at large vibration amplitude levels at resonance frequencies. It was demonstrated that the hydrothermal PZT ®lm expresses superior performance with regard to linearity and maximum vibration velocity. The linearity of frequency responses at around the resonance frequency was excellent and superior to bulk material up to high intensity operation. The characteristics of longitudinal transducers using ®lms formed under two deposition processes were tested. The maximum vibration velocity was 2.24 m/s when the thickness of the ®lm was 38 mm and the driving voltage was 145 V p±p . This velocity value was much larger than bulk PZT materials for high power applications. #

This paper proposes and evaluates a built-in position sensor for an electrostatic motor called a dual excitation multiphase electrostatic drive. The built-in sensor operates on a similar principle to typical capacitance-type linear encoders. The sensor system superimposes a high-frequency sensor signal onto a low-frequency driving signal so that it can share the same electrodes with driving operation of the motor. This paper analyses the sensor principle based on a capacitance network model of the motor that allows us to evaluate the linearity error of the proposed sensor system. The sensor was implemented on a prototype motor to evaluate its performance. The experimental results confirmed that the sensor can work successfully by sharing the same electrodes with the driving operation. The linearity error was found to be 24 µm when no driving signal was applied. As the driving signal was applied, the linearity error was found to increase up to 48 µm.

The modifications in plasma parameters and heating power under conditions of pulsed poloidal current drive (PPCD) in Reversed Field eXperiment (RFX) are modelled by the one-dimensional transport code RITM (Radiation from Impurities in Transport Model). Several channels for the PPCD effects on plasma confinement are taken into account: dissipation of externally driven poloidal currents, reduction in the electric field induced by the dynamo and decrease in magnetic fluctuations. It is demonstrated that the external currents are dissipated at the plasma edge and they cannot, alone, lead to any change in the temperature profile. The reduction in the dynamo electric field results in central peaking of the current and Ohmic power densities, accompanied, however, by a very modest rise in the central temperature. By taking into account the decrease in the level of magnetic fluctuations (predicted for PPCD conditions by non-linear MHD simulations) and the corresponding reduction of transport in the stochastic magnetic field, RITM reproduces, in agreement with experiments, a significant increase in the central temperature and a reduction in the loop voltage.

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We fabricated a piezoelectric transducer using a PZT thin film deposited by a hydrothemlal method in order IO investigate the ability for earphone. The fabricated transducer had a bimorph construction and form a diaphragm for an earphone of hearing aid. The base material was a titanium foil from 5 to 20 pm thick. Both sides of the titanium, PZT thin films 10 pm thick was deposited. Diameter of the transducer was 6 mm. Using a 5 pm titanium base, we found the transducer was able to produce 6 I dB (OdB = 2 X I O-5 Pa) per I .3 Vm driving voltage below the fimdamental resonance frequency.

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