• A. Gennai, F. Bedeschi, S. Galeotti, C. Magazzu, F. Paoletti, E. Pedreschi, F. Spinella
  INFN-Pisa, Pisa
• D. Passuello
  University of Pisa and INFN, Pisa

Superconductive cavities for future linear accelerators, such as ILC, have extremely large quality factors requiring an effective stabilization with both slow and fast tuners. Piezoelectric actuators are the most common choice for fast tuners, but one drawback for a large scale application is the limited bandwidth and the large cost of commercially available drivers. In this paper we present a low cost driver which is ideally suited for fast tuner application, large system packaging and has an excellent flexibility in its implementation. Driving piezoelectric actuators having capacitive loads up to a few microfarads in the kHz range requires amplifiers with good current output capabilities at a few hundred volts. The Piezo Control Unit we developed for the ILC Test Area at Fermilab is composed by a 6U Eurocard crate hosting 5 Piezo Driver modules capable of driving up to 10 piezoelectric actuators. Main specifications include large voltage rails (-175 V to +175V), wide signal bandwidth (DC to10 kHz) and low output noise ( <10 mVrms). The driver is equipped with both output voltage and output current monitor.

• F. Spinella, F. Bedeschi, S. Galeotti, A. Gennai, E. Pedreschi
  INFN-Pisa, Pisa
• A. Basti, D. Passuello
  University of Pisa and INFN, Pisa

Active devices based on piezoelectric actuators are widely used to dump unwanted vibrations in a variety of applications; for instance fast tuners for superconducting RF cavities. In another poster, we describe a low cost modular system of drivers for piezoelectric actuators developed at INFN-Pisa; we show here that the same system can easily be extended, with the inclusion of a simple plug-in board, to include sufficient I/O and computing capability to allow control of the device up to frequencies in the kHz range. This implementation is extremely cost effective and can be used in all situations where a high granularity distributed control system is desirable. We also show our first test results obtained using this system to control a warm single cell 1.3 GHz cavity. The cavity is perturbed using a piezoelectric actuator to generate random noise, while another piezo is used in the control loop to stabilize the resonance frequency. We use the phase of the RF pickup from the cavity as a measure of the deviation from the resonance caused by the perturbation. This simple setup allows to easily test various control algorithms without the need to work at large complex facilities.