Abstracts Brochure - CERN

MOPCH — Poster Session 26-Jun-06 16:00 - 18:00
Study of Superconducting Resonant Structures Based on a Photonic Band Gap Concept
One of the main problems of high intensity
rf accelerators is the presence of higher order
modes (HOMs) which might degrade the
beam quality. Accelerating cavities require
HOMs suppression whereas keeping a high
quality factor (Q) for the fundamental mode.
M.R. Masullo (INFN-Napoli) A. Andreone, E. Di Gennaro, F. Francomacaro,
G. Lamura (Naples University Federico II) V. Palmieri, D.
Tonini (INFN/LNL) M. Panniello, V.G. Vaccaro (Naples University
Federico II and INFN)
Both these requirements can be hardly met in closed metallic and superconducting cavities especially at high frequency,
where the configurations become cumbersome and technically unviable. Cavities based on Photonic Band
Gap (PBG) concepts showed that HOMs can be efficiently suppressed without the need of external couplers and
without affecting the fundamental mode. From our previous studies on high Q Copper cavities made of rods inserted
between two conducting plates, we have realized superconducting resonators based on bulk Niobium. Here we
present the study, the optimisation and the measurements (at room temperature and at 4 K) of superconducting
PBG based cavities operating at two different frequencies, 6 GHz and 14 GHz.All the structures are realised by a
single piece using a new machining method that minimizes the surface losses caused by the contact between different
conducting parts.
Novel Development on Superconducting Niobium Film Deposition for RF Applications
A new deposition technology has been developed,
based on a cathodic arc system
working under UHV conditions, to produce
metallic thin films. The technique presents
several advantages compared to standard
sputtering, mainly: ionized state of the evaporated
material, absence of gases to sustain
A. Cianchi, L. Catani, D. D. Di Giovenale, J. Lorkiewicz (INFN-
Roma II) J. Langner, M. S. Sadowski, P.S. Strzyzewski (The Andrzej
Soltan Institute for Nuclear Studies, Centre Swierk) V. M. Merlo, S.
Tazzari (Università di Roma II Tor Vergata) B.R. Ruggiero, R. Russo
(ICIB)
the discharge, much higher energy of atoms reaching the substrate surface, possibility to apply bias to the substrate
and to guide the arc plasma using magnetic fields. Recent results on superconducting Niobium films deposited
under several conditions and on various substrates are reported. The RF properties of the produced samples are very
encouraging in view of applications to high field RF cavities. A cavity deposition system has been developed and
characterized.
High Pressure Rinsing Water Jet Characterization
High pressure rinsing is widely used as the
final wet step in the high field superconducting
cavities production. The interaction of
an high speed ultra pure water jet with the
P. Michelato, E. Cavaliere, M. Fusetti, C. Pagani, P. Pierini, D. Sertore
(INFN/LASA)
niobium surface depends on various parameters such as water pressure, water throughput, treatment duration, cavity
rotation speed, etc. In this paper we illustrate a simple technique for the characterization of water jet parameters
based on the momentum transfer between the water jet and a load cell. The jet profile and its dependence on water
pressure as well as the force exerted by the jet on the surface are easily measured. Moreover a portable apparatus
has been set up and the information gathered in different laboratories will be used for a quantitative comparison of
the different HPR systems. These measurements allow to study the correlation of the jet parameters with the effects
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MOPCH167
MOPCH168
MOPCH169