Control system for compensation of Lorentz force detuning for Superconducting Cavities

The paper presents concept and results of mechanical compensation of Lorenz force detuning in Superconducting Cavities (SC) used in Linear Electron Accelerators. Usually the piezoelectric actuators are used for that purpose. However they require high voltage driving and therefore the driving circuit must fulfil special operation requirements. Moreover the piezo is a capacitive load and generation of driving pulses must take into account all the problems it can create (unstability, dangerous transient effects, etc.). The special multichannel high-voltage amplifier together with control circuitry was developed and manufactured. It fulfils the requirements but in order to optimise the operational characteristics of the piezo driver (power consumption, requirements on supply voltage) other ideas were also evaluated. The new piezo driver based on resonance excitation was developed and its prototype was manufactured. In the paper the results of measurements done in real environment of FLASH [1] accelerator are presented.