| Paper |
Title |
Page |
| TUPKF025 |
Superconducting Niobium Film for RF Applications
|
1021 |
| |
- A. Cianchi, L. Catani, A. Cianchi, S. Tazzari
INFN-Roma II, Roma
- Y.H. Akhmadeev
Institute of High Current Electronics, Tomsk
- A. Andreone, G. Cifariello, E. Di Gennaro, G. Lamura
Naples University Federico II, Napoli
- J.L. Langner
The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
- R.R. Russo
Università di Roma II Tor Vergata, Roma
|
|
| |
Thin niobium film coated copper RF cavities are an interesting possible alternative to bulk-Nb cavities since copper is much cheaper than niobium, it has higher thermal conductivity and a better mechanical stability. Unfortunately, the observed degradation of the quality factor with increased cavity voltage of sputtered accelerating cavities restricts their usage in future large linear accelerators needing gradients higher than 15MV/m. We are developing an alternate deposition technology, based on a cathodic arc system working in UHV conditions. Its main advantages compared to standard sputtering are the ionized state of the evaporated material, the absence of gases to sustain the discharge, the much higher energy of atoms reaching the substrate surface and the possibility of higher deposition rates. To ignite the arc we use a Nd-YAG pulsed laser focused on the cathode surface that provides a reliable and ultraclean trigger. Recent results on the characterization of niobium film samples produced under different conditions are presented showing that the technique can produce bulk-like films suitable for RF superconducting applications.
|
|
| TUPLT069 |
Approaching to a Mono-modal Accelerating Cavity based on Photonic Band-gap Concepts
|
1309 |
| |
- M.R. Masullo
INFN-Napoli, Napoli
- A. Andreone, E. Di Gennaro, G. Lamura
Naples University Federico II, Napoli
- F. Francomacaro, M. Panniello, V.G. Vaccaro
Naples University Federico II and INFN, Napoli
- G. Keppel, V. Palmieri, D. Tonini
INFN/LNL, Legnaro, Padova
|
|
| |
One of the main problem of high intensity accelerators is the presence of high order modes (HOMs) which might degrade the beam quality. Accelerating cavities require HOMs suppression while keeping high quality factor (Q) fundamental mode. Both these requirements can be hardly met in closed metallic cavities. In low frequency cases and for particular geometries it is possible to partially suppress HOMs, but at high frequencies and for superconducting cavities configuration becomes cumbersome and technically unviable. We propose here a high Q cavity based on Photonic Band Gap (PBG) concepts, operating in the microwave region. The cavity consists of a two-dimensional lattice, where posts (dielectric, metallic or superconducting) are sandwiched by two conducting plates. This sandwich exhibits two kinds of frequency bands: 'pass-bands' and 'stop-bands'. It is possible to localize modes in an equivalent cavity obtained by removing posts. These modes are localized in the 'cavity'. In this way, one can obtain a quasi-mono-modal cavity: high Q fundamental mode and HOMs falling into the pass bands. We will present the study, the optimisation and the measurements of our metallic (Copper) PBG structure working in the 2-20 GHz range. The development of a different cryogenic set-up, necessary to characterise an all superconducting or an hybrid (dielectric/metallic) structure, is under way.
|
|