Paparella, R.

Paper	Title	Page
MOPP146	The Coaxial Tuner for ILCTA_NML at Fermilab	895
	A. Bosotti, C. Pagani, N. Panzeri, R. Paparella INFN/LASA, Segrate (MI)
	The piezo Blade Tuner prototype has been successfully tested inside the horizontal cryostat, CHECHIA, at DESY and extensive tests at BESSY are planned. As suggested by the cold test results, a few minor modifications have been implemented and a set of 8 improved devices is under construction for the installation in the second module of ILCTA at Fermilab. This reviewed design, together with a simplified helium tank in prototyping, should hopefully fulfill also the XFEL requests in term of performances and cost. In particular the use of thicker blades and their slightly different distribution along the circumference produces the increase of the tuner strength and stiffness that is needed in order to fulfill the pressure vessel regulations for qualification. As in the past, two equivalent devices, respectively in titanium and stainless steel, have been designed to maintain open the possibility of the use of a SS helium vessel once the required technology were developed. The results of the extensive mechanical tests performed to validate the estimated performances and life time are also presented.
THPPGM01	A Control and Systems Theory Approach to the High Gradient Cavity Detuning Compensation	2952
	R. Paparella INFN/LASA, Segrate (MI)
	The compensation of dynamic detuning is of primary importance in order to operate TESLA type cavities at the high accelerating gradient foreseen for the ILC (31.5 MV/m). This article firstly resumes recent successful experiences of open loop compensation of the Lorentz force detuning, repetitive and synchronous to the RF pulse, using fast piezoelectric actuators with different fast tuning systems. Possible strategies and results for the closed loop compensation of the stochastic microphonic detuning are also presented. Lastly, a deep characterization of the system under control is given, exploiting the system transfer functions acquired through both installed piezo actuators/sensors and phase locked measurements. This ultimately allows the analytical modeling of the behavior of cavity detuning and of its active compensation with piezoelectric actuators.
	Slides
MOPP120	Full Characterization of the Piezo Blade Tuner for Superconducting RF Cavities	838
	A. Bosotti, C. Pagani, N. Panzeri, R. Paparella INFN/LASA, Segrate (MI) C. Albrecht, K. Jensch, R. Lange, L. Lilje DESY, Hamburg J. Knobloch, O. Kugeler, A. Neumann BESSY GmbH, Berlin
	Cavity tuners are mechanical devices designed to precisely match the resonant frequency of the superconducting (SC) cavity to the RF frequency synchronous with the beam. The blade tuner is mounted coaxially to the cavity and changes the resonator frequency by varying its length. A high tuning range is desired together with small mechanical hysteresis, to allow easy and reproducible resonator setup operations. High stiffness is also demanded to the tuner system both to ensure mechanical stability and to mitigate the frequency instabilities induced by perturbations. In high gradient SC resonators, the main sources of resonant frequency instability are the Lorentz Force Detuning (LFD) under pulsed mode operation, and the microphonic noise, in continuous wave (CW) with high loaded quality factors. Piezoceramic elements add dynamic tuning capabilities to the system, allowing fast compensation of these instabilities with the help of feed-forward and feedback loops. The piezo blade tuner has been extensively tested both at room temperature and at cold once assembled on a TESLA type cavity in its final configuration. This paper presents the summary of the complete characterization tests.