SRF2013 - List of Authors (Rossi, A.A.)

Paper

Title

Page

R&D Progress in SRF Surface Preparation With Centrifugal Barrel Polishing (CBP) for both Nb and Cu

398

A.D. Palczewski
JLAB, Newport News, Virginia, USA
B. Bullock
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
C.A. Cooper
Fermilab, Batavia, USA
S.C. Joshi
RRCAT, Indore (M.P.), India
A. Navitski
DESY, Hamburg, Germany
A.A. Rossi
INFN/LNL, Legnaro (PD), Italy

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Centrifugal Barrel polishing (CBP) is becoming a common R&D tool for SRF cavity preparation around the word. During the CBP process a cylindrically symmetric SRF cavity is filled with relatively cheap and environmentally friendly abrasive and sealed. The cavity is then spun around the cylindrical axis at high speeds uniformly conditioning the inner surface. This uniformity is especially relevant for SRF application because many times a single manufacturing defects limits cavity’s performance well below it’s theoretical limit. In addition CBP has created surfaces with roughness’s on the order of 10’s of nm which create a unique surface for wet chemistry or thin film deposition. CBP is now being utilized at Jefferson Laboratory, Fermi Laboratory and Cornell University in the US, Ko Enerugi Kasokuki Kenkyu Kiku in Japan, Deutsches Elektronen-Synchrotron in Germany, Laboratori Nazionali di Legnaro in Italy, and Raja Ramanna Centre for Advanced Technology in India. In this talk we will present current CBP research from each lab including polishing recipes, equipment, post CBP chemistry/heat treatment, and subsequent cryogenic cavity tests on niobium as well as copper cavities.

Slides TUIOB01 [2.204 MB]

TUIOC03

Fluorine Free Ionic Liquid Electropolishing of Niobium Cavities

410

V.B. Pastushenko, O.V. Malkova, V. Palmieri, A.A. Rossi, F. Stivanello, G. Yu
INFN/LNL, Legnaro (PD), Italy
G. Yu
CIAE, Beijing, People's Republic of China

Ionic liquids are an emerging breakthrough in green chemistry since the years 2000. In 2006, INFN-LNL was the first to apply a mixture of Choline Chloride and Urea to Niobium electropolishing. It was found that mirror like surfaces could be obtained at temperature higher than 120°C, with high throwing power. Subsequently the process was successfully applied to the electropolishing of a 6 GHz monocell cavity with the addition of sulphamic acid. In this work, we will report an intense investigation of the possible variants of the original recipe. We studied the influence on Niobium surface roughness of several parameters such as: other sulphamic, ammonium and carboxylic containing additives different than sulfamic acid, the possible substitution of Urea with ethylene glycol and malic acid, the current regime; the electrolyte temperature and the cathode shape, rotating horizontal electropolishing versus vertical electropolishing. Due to the cavity hollow cylindrical shape, the electrolyte temperature appeared to be the most crucial parameters among those above mentioned for a uniform dissolution of niobium.

Slides TUIOC03 [14.464 MB]

TUIOC05

Purification of 6 GHz Cavities by Induction Heating

419

A.A. Rossi, A. Battistello, M. Checchin, V. Palmieri, S. Stark, F. Stivanello, R.K. Thakur, G. Yu
INFN/LNL, Legnaro (PD), Italy

We have developed an innovative technique for purification of bulk-Nb 6GHz RF cavities under ultra-high vacuum (UHV) system. The main advantages of 6 GHz bulk-Nb cavities are saving cost, materials and time to collect statistics of surface treatments and RF test. Cavities are RF tested before and after high temperature treatment under UHV conditions. Induction heating method is used to anneal the cavity at temperatures higher than 2000°C and close to the melting point of Nb for less than a minute while few seconds at maximum temperature. Before RF test and UHV annealing, the surface treatment processes like tumbling, chemical, electro-chemical (such as BCP and EP), ultrasonic cleaning and high pressure rinsing (HPR) have been employed. This kind of Nb 6 GHz cavity purification allow to reduce hydrogen, oxygen and other elemental impurities content, which effects on cavity Q-factor degradation, by a rapid annealing over 2000°C and a subsequent rapid reduction at room temperature.

Slides TUIOC05 [42.171 MB]

THP096

Recent Upgrade of Ultra-Broadband RF System for Cavity Characterization

1151

S. Stark, V. Palmieri, A.M. Porcellato, A.A. Rossi
INFN/LNL, Legnaro (PD), Italy
V. Palmieri
Univ. degli Studi di Padova, Padova, Italy

The first computer controlled RF system for SC cavity characterization entered into operation at INFN-LNL in 1994. Since then it has been successfully used for testing SC cavities of different shapes and frequencies. Recently we performed an important upgrade on it in order to cover a wider frequency range and to take advantage of the better performance of nowadays electronic devices. The paper describes the present system layout, dedicated software, sequences of calibration and testing procedures and moreover discusses further upgrading possibilities.

Paper	Title	Page
TUIOB01	R&D Progress in SRF Surface Preparation With Centrifugal Barrel Polishing (CBP) for both Nb and Cu	398
	A.D. Palczewski JLAB, Newport News, Virginia, USA B. Bullock Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA C.A. Cooper Fermilab, Batavia, USA S.C. Joshi RRCAT, Indore (M.P.), India A. Navitski DESY, Hamburg, Germany A.A. Rossi INFN/LNL, Legnaro (PD), Italy
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Centrifugal Barrel polishing (CBP) is becoming a common R&D tool for SRF cavity preparation around the word. During the CBP process a cylindrically symmetric SRF cavity is filled with relatively cheap and environmentally friendly abrasive and sealed. The cavity is then spun around the cylindrical axis at high speeds uniformly conditioning the inner surface. This uniformity is especially relevant for SRF application because many times a single manufacturing defects limits cavity’s performance well below it’s theoretical limit. In addition CBP has created surfaces with roughness’s on the order of 10’s of nm which create a unique surface for wet chemistry or thin film deposition. CBP is now being utilized at Jefferson Laboratory, Fermi Laboratory and Cornell University in the US, Ko Enerugi Kasokuki Kenkyu Kiku in Japan, Deutsches Elektronen-Synchrotron in Germany, Laboratori Nazionali di Legnaro in Italy, and Raja Ramanna Centre for Advanced Technology in India. In this talk we will present current CBP research from each lab including polishing recipes, equipment, post CBP chemistry/heat treatment, and subsequent cryogenic cavity tests on niobium as well as copper cavities.
	Slides TUIOB01 [2.204 MB]

TUIOC03	Fluorine Free Ionic Liquid Electropolishing of Niobium Cavities	410
	V.B. Pastushenko, O.V. Malkova, V. Palmieri, A.A. Rossi, F. Stivanello, G. Yu INFN/LNL, Legnaro (PD), Italy G. Yu CIAE, Beijing, People's Republic of China
	Ionic liquids are an emerging breakthrough in green chemistry since the years 2000. In 2006, INFN-LNL was the first to apply a mixture of Choline Chloride and Urea to Niobium electropolishing. It was found that mirror like surfaces could be obtained at temperature higher than 120°C, with high throwing power. Subsequently the process was successfully applied to the electropolishing of a 6 GHz monocell cavity with the addition of sulphamic acid. In this work, we will report an intense investigation of the possible variants of the original recipe. We studied the influence on Niobium surface roughness of several parameters such as: other sulphamic, ammonium and carboxylic containing additives different than sulfamic acid, the possible substitution of Urea with ethylene glycol and malic acid, the current regime; the electrolyte temperature and the cathode shape, rotating horizontal electropolishing versus vertical electropolishing. Due to the cavity hollow cylindrical shape, the electrolyte temperature appeared to be the most crucial parameters among those above mentioned for a uniform dissolution of niobium.
	Slides TUIOC03 [14.464 MB]

TUIOC05	Purification of 6 GHz Cavities by Induction Heating	419
	A.A. Rossi, A. Battistello, M. Checchin, V. Palmieri, S. Stark, F. Stivanello, R.K. Thakur, G. Yu INFN/LNL, Legnaro (PD), Italy
	We have developed an innovative technique for purification of bulk-Nb 6GHz RF cavities under ultra-high vacuum (UHV) system. The main advantages of 6 GHz bulk-Nb cavities are saving cost, materials and time to collect statistics of surface treatments and RF test. Cavities are RF tested before and after high temperature treatment under UHV conditions. Induction heating method is used to anneal the cavity at temperatures higher than 2000°C and close to the melting point of Nb for less than a minute while few seconds at maximum temperature. Before RF test and UHV annealing, the surface treatment processes like tumbling, chemical, electro-chemical (such as BCP and EP), ultrasonic cleaning and high pressure rinsing (HPR) have been employed. This kind of Nb 6 GHz cavity purification allow to reduce hydrogen, oxygen and other elemental impurities content, which effects on cavity Q-factor degradation, by a rapid annealing over 2000°C and a subsequent rapid reduction at room temperature.
	Slides TUIOC05 [42.171 MB]

THP096	Recent Upgrade of Ultra-Broadband RF System for Cavity Characterization	1151
	S. Stark, V. Palmieri, A.M. Porcellato, A.A. Rossi INFN/LNL, Legnaro (PD), Italy V. Palmieri Univ. degli Studi di Padova, Padova, Italy
	The first computer controlled RF system for SC cavity characterization entered into operation at INFN-LNL in 1994. Since then it has been successfully used for testing SC cavities of different shapes and frequencies. Recently we performed an important upgrade on it in order to cover a wider frequency range and to take advantage of the better performance of nowadays electronic devices. The paper describes the present system layout, dedicated software, sequences of calibration and testing procedures and moreover discusses further upgrading possibilities.