High-Power Piezoelectric Tuner Driver for Lorentz Force Compensation

Superconducting radio frequency (SRF) cavities, used in modern linear particle accelerators, undergo a mechanical strain due to the Lorentz force caused by the applied electrical field. During pulsed-mode operation, the resulting deformation causes dynamic detuning with the magnitude depending on mechanical properties of the cavity, an RF pulse rate and their profile. This effect causes a considerable loss of acceleration performance. Therefore, it is usually actively compensated, most commonly with fast piezoelectric actuators. The Micro Telecommunications Computing Architecture (MicroTCA.4) standard was developed to accommodate control and data acquisition electronic systems of large-scale physics applications. This paper presents the pioneering design of a high-power amplifier implemented using MicroTCA.4 technology. So far, other MicroTCA.4 high-power piezo driver has not been developed. The design of the driver was optimized for driving large-capacitance piezo actuators. Several possible architectures of the driver are presented and compared, taking into consideration the power and cooling limitations of the MicroTCA.4. The design of a two-channel piezo driver dedicated for the European spallation source (ESS) accelerator and its initial laboratory test results are also discussed.