Use of piezoelectric actuators in cold condition for phase locking of superconducting Quarter Wave Resonators Sahu B.K.1, Ahuja R.1, Singh K.1, Chowdhury G.K.1, Rai A.1, Patra P.1, Pandey A.1, Mathuria D.S.1, Dutt R.N.1, Ghosh S.1, Kanjilal D.1, Roy A.1 1Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi, India Abstract The need of the rf control system of superconducting resonators is to provide amplitude and phase stability. As the superconducting(SC) cavities often have a high Q (>108, the fluctuation of resonant frequency acts as the main disturbance to the stabilization process. The existing phase locking scheme of the quarter wave resonators (QWR) in the first operational module of the superconducting heavy ion linear accelerator consists of electronic and mechanical tuners. The mechanical tuner uses pure helium gas to flex the Niobium tuner bellows for tuning the frequency in slow time scale. The helium gas operated slow tuner turns out to be complicated, somewhat unreliable and expensive for long term operation of the linac. In an alternate scheme to handle the slow time part of the phase control, the tuner bellows is deflected by using a piezoelectric crystal for fine adjustment of the frequency. The piezoelectric actuator is used in closed loop along with dynamic I-Q based electronic tuner inside the cryostat to phase lock the superconducting cavities. The stiffness and stroke of piezoelectric actuators in cold condition was found to be sufficient to control the maximum frequency variation around the master oscillator. Top Keywords Superconducting cavity, Phase control, Piezoelectric actuator, P-I control. Top |