SRF2013 - List of Authors (Zhang, P.)

Paper	Title	Page
TUP076	Preliminary Results of Nb Thin Film Coating for HIE-ISOLDE SRF Cavities Obtained by Magnetron Sputtering	620
	A. Sublet, I. Aviles Santillana, S. Calatroni, A. D'Elia, N.M. Jecklin, I. Mondino, S. Prunet, M. Therasse, W. Venturini Delsolaro, P. Zhang CERN, Geneva, Switzerland
	Funding: Work supported in part by a Marie Curie Early Initial Training Network Fellowship of the European Community's 7th Programme under contract number PITN-GA-2010-264330-CATHI. In the context of the HIE-ISOLDE upgrade at CERN, several new facilities for the niobium sputter coating of QWR-type superconducting RF accelerating cavities have been developed, built, and successfully operated. In order to further optimize the production process of these cavities the magnetron sputtering technique has been further investigated and continued as an alternative to the already successfully operational DC bias diode sputtering method. The purpose of this poster is to present the results obtained with this technique. The Nb thickness profile along the cavity and its correlation with the electro-magnetic field distribution inside the cavity are discussed. Film structure, morphology and Residual Resistivity Ratio (RRR) will be considered as well and compared with films obtained by DC bias diode sputtering. Finally these results will be compared with RF characterization and measurement of a production-like magnetron-coated cavity.

THP048	The Influence of Tuners and Temperature on the Higher Order Mode Spectrum for 1.3 GHz SCRF Cavities	1016
	R. Ainsworth Royal Holloway, University of London, Surrey, United Kingdom N. Baboi, M.K. Grecki, T. Wamsat DESY, Hamburg, Germany N. Eddy Fermilab, Batavia, USA S. Molloy ESS, Lund, Sweden P. Zhang CERN, Geneva, Switzerland
	Higher Order Modes are of concern for superconducting cavities as they can drive instabilities and so are usually damped and monitored. With special dedicated electronics, HOMs can provide information on the position on the beam. It has been proposed that piezo tuners used to keep the cavities operating at 1.3 GHz could alter the HOM spectrum altering the calibration constants used to read out the beam position affecting long term stability of the system. Also, of interest is how the cavity reacts to the slow tuner. Detuning and the retuning the cavity may alter the HOM spectrum. This is of particular interest for future machines not planning to use dedicated HOM damping as the tuning procedure may shift the frequency of HOMs onto dangerous resonances. The effect of temperature on the HOM spectrum is also investigated. An investigation of these effects has been performed at FLASH and the results are presented including numerical simulations used to predict the resulting cavity distortion.

THP084	The Tuning System for the HIE-ISOLDE High-Beta Quarter Wave Resonator	1121
	P. Zhang, L. Alberty, L. Arnaudon, K. Artoos, S. Calatroni, O. Capatina, A. D'Elia, Y. Kadi, I. Mondino, T. Renaglia, D. Valuch, W. Venturini Delsolaro CERN, Geneva, Switzerland A. D'Elia UMAN, Manchester, United Kingdom
	Funding: Work supported in part by a Marie Curie Early Initial Training Network Fellowship of the European Community's 7th Programme under contract number PITN-GA-2010-264330-CATHI. A new linac using superconducting quarter-wave resonators (QWR) is under construction at CERN in the framework of the HIE-ISOLDE project. The QWRs are made by Niobium sputtered on a bulk Copper substrate. The working frequency at 4.5 K is 101.28 MHz and they will provide 6 MV/m accelerating gradient on the beam axis with a total maximum power dissipation of 10 W on cavity walls. A tuning system is required in order to both minimize the forward power variation in beam operation and to compensate the unavoidable uncertainties in the frequency shift during the cool-down process. The tuning system has to fulfill a complex combination of RF, structural and thermal requirements. The paper presents the functional specifications and details the tuning system RF and mechanical design and simulations. The results of the tests performed on a prototype system are discussed and the industrialization strategy is presented in view of final production.

Paper

Title

Page

Preliminary Results of Nb Thin Film Coating for HIE-ISOLDE SRF Cavities Obtained by Magnetron Sputtering

620

A. Sublet, I. Aviles Santillana, S. Calatroni, A. D'Elia, N.M. Jecklin, I. Mondino, S. Prunet, M. Therasse, W. Venturini Delsolaro, P. Zhang
CERN, Geneva, Switzerland

Funding: Work supported in part by a Marie Curie Early Initial Training Network Fellowship of the European Community's 7th Programme under contract number PITN-GA-2010-264330-CATHI.
In the context of the HIE-ISOLDE upgrade at CERN, several new facilities for the niobium sputter coating of QWR-type superconducting RF accelerating cavities have been developed, built, and successfully operated. In order to further optimize the production process of these cavities the magnetron sputtering technique has been further investigated and continued as an alternative to the already successfully operational DC bias diode sputtering method. The purpose of this poster is to present the results obtained with this technique. The Nb thickness profile along the cavity and its correlation with the electro-magnetic field distribution inside the cavity are discussed. Film structure, morphology and Residual Resistivity Ratio (RRR) will be considered as well and compared with films obtained by DC bias diode sputtering. Finally these results will be compared with RF characterization and measurement of a production-like magnetron-coated cavity.

THP048

The Influence of Tuners and Temperature on the Higher Order Mode Spectrum for 1.3 GHz SCRF Cavities

1016

R. Ainsworth
Royal Holloway, University of London, Surrey, United Kingdom
N. Baboi, M.K. Grecki, T. Wamsat
DESY, Hamburg, Germany
N. Eddy
Fermilab, Batavia, USA
S. Molloy
ESS, Lund, Sweden
P. Zhang
CERN, Geneva, Switzerland

Higher Order Modes are of concern for superconducting cavities as they can drive instabilities and so are usually damped and monitored. With special dedicated electronics, HOMs can provide information on the position on the beam. It has been proposed that piezo tuners used to keep the cavities operating at 1.3 GHz could alter the HOM spectrum altering the calibration constants used to read out the beam position affecting long term stability of the system. Also, of interest is how the cavity reacts to the slow tuner. Detuning and the retuning the cavity may alter the HOM spectrum. This is of particular interest for future machines not planning to use dedicated HOM damping as the tuning procedure may shift the frequency of HOMs onto dangerous resonances. The effect of temperature on the HOM spectrum is also investigated. An investigation of these effects has been performed at FLASH and the results are presented including numerical simulations used to predict the resulting cavity distortion.

THP084

The Tuning System for the HIE-ISOLDE High-Beta Quarter Wave Resonator

1121

P. Zhang, L. Alberty, L. Arnaudon, K. Artoos, S. Calatroni, O. Capatina, A. D'Elia, Y. Kadi, I. Mondino, T. Renaglia, D. Valuch, W. Venturini Delsolaro
CERN, Geneva, Switzerland
A. D'Elia
UMAN, Manchester, United Kingdom

Funding: Work supported in part by a Marie Curie Early Initial Training Network Fellowship of the European Community's 7th Programme under contract number PITN-GA-2010-264330-CATHI.
A new linac using superconducting quarter-wave resonators (QWR) is under construction at CERN in the framework of the HIE-ISOLDE project. The QWRs are made by Niobium sputtered on a bulk Copper substrate. The working frequency at 4.5 K is 101.28 MHz and they will provide 6 MV/m accelerating gradient on the beam axis with a total maximum power dissipation of 10 W on cavity walls. A tuning system is required in order to both minimize the forward power variation in beam operation and to compensate the unavoidable uncertainties in the frequency shift during the cool-down process. The tuning system has to fulfill a complex combination of RF, structural and thermal requirements. The paper presents the functional specifications and details the tuning system RF and mechanical design and simulations. The results of the tests performed on a prototype system are discussed and the industrialization strategy is presented in view of final production.