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High-Purity TIG Welding at Michigan State University Chris Compton 5/24/2007. Acknowledgments. Michigan State University Steve Bricker, Terry Grimm, Dan Pendell Fermi National Accelerator Laboratory Claire Antoine, Bob Kephart, Rob Schuessler. Outline. Motivation Baseline Measurements
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High-Purity TIG Welding at Michigan State UniversityChris Compton5/24/2007
Acknowledgments • Michigan State University Steve Bricker, Terry Grimm, Dan Pendell • Fermi National Accelerator Laboratory Claire Antoine, Bob Kephart, Rob Schuessler
Outline • Motivation • Baseline Measurements • First Cavity Test Results • RRR Sample Measurements • High-Purity TIG Welding Chamber • Welding Chamber Design • Construction Status • Research Schedule
Motivation • Reduce E-B welding • Cost and time savings on cavity fabrication • Cost savings on cavity infrastructure • Eases complex welding and tooling • New cavity geometries • End Assemblies • Cavity repairs • Prototyping
Test Results of first TIG cavity Tests results at 2 K Generally infer a surface RRR value smaller than bulk RRR specification
RRR Baseline Measurements • RRR Samples Tested at Fermi • High RRR,value from vendor • Reactor Grade niobium • TIG welded niobium • Bubble Chamber
Welding Chamber Construction [1] • Initial Design • 1.
Welding Chamber Construction [3] • Gas system
Welding Chamber Construction [4] • Filter System • Reduce residual gas content < 1ppb, similar to E-B chamber pressure
Welding Chamber Construction [5] • Purity Control • Series 3000 Trace Oxygen Analyzer • Range 0-1 parts per million (ppm) • ±5% Accuracy • 90% full scale response < 10 sec.
RRR Sample Results • Samples sent to Fermi-Welded in TIG chamber
Electron-Beam Welding • RRR degradation from e-b welding environment Welded at Dornier 1994* RRR decreased (20-40 ppb) Welded at ACCEL, 1996 at 2 x 10-5 mbar* (20 ppb) Welded at Zanon, 1995* RRR decreased (25 –60 ppb) Welded at Sciaky 50 kV 48 mA 12 inch/min focus 250/250 (0.05” beam) * TESLA Report 2003-07, W. Singer, et al.
Schedule • Recheck RRR measurements • Chamber modifications (80 ppb best to date) • Main seal (leak) • Torch purge gas • Add Titanium getter • Weld improved niobium samples for RRR measurements • Fabricate single cell cavity using TIG Chamber • 1.3 GHz, Beta = 0.81, Proton Driver Prototype • Dies and infrastructure complete • Niobium from Fermi • Cold performance testing at MSU