SRF2011 - List of Authors (Crawford, A.C.)

Paper	Title	Page
TUPO015	Standard Procedures of ILC High Gradient Cavity Processing at Jefferson Lab	391
	R.L. Geng JLAB, Newport News, Virginia, USA A.C. Crawford CLASSE, Ithaca, New York, USA
	Funding: This work was authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 We describe the JLab standard procedures of ILC cavity processing and handling for reproducible high gradient high Q0 results. The procedure begins with mixing fresh electrolyte with the molar ratio of HF:H2O:H2SO4 in the range that is compatible with that in the original Siemens recipe. Three key process parameters, namely the acid flow rate, the polish cell voltage and the cavity body temperature, are identified and in control. Our experience shows that optimal EP is achieved in the continuous current oscillation mode. The appearance of current oscillation also serves as a sensitive in-situ QA/QC indicator. The “auto polishing” procedure is introduced by continuing the acid flow and cavity rotation after the voltage is shut off. This effectively reduces sulfur-bearing niobium oxide granules, an inherent contaminant of the EP process. An elaborate post-EP cleaning procedure includes low-pressure water rinsing, HOM coupler brushing and ultrasonic cleaning with detergent. The vacuum furnace heat treatment procedure is updated. A no-touch bead-pull method is established. Slow pump down is routinely applied to prevent recontamination of the cavity surface.

TUPO028	Qualification of the Second Batch Production 9-Cell Cavities Manufactured by AES and Validation of the First US Industrial Cavity Vendor for ILC	433
	R.L. Geng, D. Forehand, B.A. Golden, P. Kushnick, R.B. Overton JLAB, Newport News, Virginia, USA M. Calderaro, E. Peterson, J. Rathke AES, Medford, NY, USA M.S. Champion, J. Follkie Fermilab, Batavia, USA A.C. Crawford CLASSE, Ithaca, New York, USA
	Funding: This work was authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 One of the major goals of ILC SRF cavity R&D is to develop industrial capabilities of cavity manufacture and processing in all three regions. In the past several years, Jefferson Lab, in collaboration with Fermi National Accelerator Laboratory, has processed and tested all the 9-cell cavities of the first batch (4 cavities) and second batch (6 cavities) production cavities manufactured by Advanced Energy Systems Inc. (AES). Over the course, close information feedback was maintained, resulting in changes in fabrication and processing procedures. A light buffered chemical polishing was introduced, removing the weld splatters that could not be effectively removed by heavy EP alone. An 800 Celsius 2 hour vacuum furnace heat treatment procedure replaced the original 600 Celsius 10 hour procedure. Four out of the six 9-cell cavities of the second production bath achieved a gradient of 36-41 MV/m at a Q0 of more than 8·10⁹ at 35 MV/m. This result validated AES as the first “ILC certified” industrial vendor in the US for ILC cavity manufacture.

Paper

Title

Page

Standard Procedures of ILC High Gradient Cavity Processing at Jefferson Lab

391

R.L. Geng
JLAB, Newport News, Virginia, USA
A.C. Crawford
CLASSE, Ithaca, New York, USA

Funding: This work was authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
We describe the JLab standard procedures of ILC cavity processing and handling for reproducible high gradient high Q0 results. The procedure begins with mixing fresh electrolyte with the molar ratio of HF:H2O:H2SO4 in the range that is compatible with that in the original Siemens recipe. Three key process parameters, namely the acid flow rate, the polish cell voltage and the cavity body temperature, are identified and in control. Our experience shows that optimal EP is achieved in the continuous current oscillation mode. The appearance of current oscillation also serves as a sensitive in-situ QA/QC indicator. The “auto polishing” procedure is introduced by continuing the acid flow and cavity rotation after the voltage is shut off. This effectively reduces sulfur-bearing niobium oxide granules, an inherent contaminant of the EP process. An elaborate post-EP cleaning procedure includes low-pressure water rinsing, HOM coupler brushing and ultrasonic cleaning with detergent. The vacuum furnace heat treatment procedure is updated. A no-touch bead-pull method is established. Slow pump down is routinely applied to prevent recontamination of the cavity surface.

TUPO028

Qualification of the Second Batch Production 9-Cell Cavities Manufactured by AES and Validation of the First US Industrial Cavity Vendor for ILC

433

R.L. Geng, D. Forehand, B.A. Golden, P. Kushnick, R.B. Overton
JLAB, Newport News, Virginia, USA
M. Calderaro, E. Peterson, J. Rathke
AES, Medford, NY, USA
M.S. Champion, J. Follkie
Fermilab, Batavia, USA
A.C. Crawford
CLASSE, Ithaca, New York, USA

Funding: This work was authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
One of the major goals of ILC SRF cavity R&D is to develop industrial capabilities of cavity manufacture and processing in all three regions. In the past several years, Jefferson Lab, in collaboration with Fermi National Accelerator Laboratory, has processed and tested all the 9-cell cavities of the first batch (4 cavities) and second batch (6 cavities) production cavities manufactured by Advanced Energy Systems Inc. (AES). Over the course, close information feedback was maintained, resulting in changes in fabrication and processing procedures. A light buffered chemical polishing was introduced, removing the weld splatters that could not be effectively removed by heavy EP alone. An 800 Celsius 2 hour vacuum furnace heat treatment procedure replaced the original 600 Celsius 10 hour procedure. Four out of the six 9-cell cavities of the second production bath achieved a gradient of 36-41 MV/m at a Q0 of more than 8·10⁹ at 35 MV/m. This result validated AES as the first “ILC certified” industrial vendor in the US for ILC cavity manufacture.