| Paper | Title | Page |
|---|
| TUP73 | Plasma Treatment of Bulk Nb Surface in the Ar/Cl2 Discharge | 323 |
| | - M. Raskovic, L. Vuskovic, S. Popovic
Old Dominion University - A. -M. Valente-Feliciano, L. Phillips
TJNAF
| |
| | The preparation of the cavity walls has been one of the
major challenges in the superconducting radio-frequency
(SRF) accelerator technology. Therefore, constant
research and development effort is devoted to develop
surface preparation processes that will improve roughness
and lower the level of impurities, like hydrogen or
oxygen, embedded in bulk Nb, having in the same time
reasonable etching rates. Plasma based surface
modification provides an excellent opportunity to achieve
these goals. We present Ar/Cl2 discharge treatment of
bulk Nb where we achieved etching rates comparable to
the rates obtained with the electropolishing method
without introducing impurities in Nb. The current
experiments were performed on disk shaped Nb samples,
exposed to plasma produced in a microwave discharge
system. Surface composition and topology measurements
were carried out before and after plasma treatment. Upon
determining optimal experimental conditions on disk
shaped samples, we will apply the same procedure on the
single cell cavities, pursuing improvement of their RF
performance. | |
| WE204 | Application of plasma cleaning to cavities processing | 400 |
| | - N. Patron, S. Deambrosis, S. Stark, V. Palmieri
INFN-LNL - M. Baecker
Fachhochschule Aachen - L. Phillips
TJLNAF
| |
| | very versatile and inexpensive technique used in a variety
of surface processes such as dry etching, surface
treatments and modification of surface wettability. After
initial studies on different configurations of RF, MW and
DC atmospheric plasma devices we have analyzed the
modification of water wettability induced by helium
atmospheric plasma.
We have applied a resonance atmospheric plasma
cleaning step to further clean a 6 GHz Nb seamless cavity
observing an increment in the Q0 from 7x1e6 to 2x1e7 in
only 30 minutes of process. The increased wettability due
to the plasma action on the inner cavity surface has
proved to enhance the beneficial action of water rinsing
pushing the Q0 value further up close to 3x1e7. | |
 | Slides(PDF) | |