Update on Be Wall Cavity

1. Update on Be Wall Cavity Steve Virostek Lawrence Berkeley National Lab MTA RF Workshop November 15, 2010

2. Current Status • Funding is available (LBNL account) for the design/fab project (~$200k) • Several design concepts are being developed based on preliminary discussions (R. Palmer, S. Virostek, D. Li) • A preliminary 3D CAD model of the nominal design concept has been completed by Allan DeMello (LBNL) • Quotes have been obtained for Be material in various configurations for the different design concepts • Currently analyzing the manufacturing risks of different approaches: brazing (Be to Cu or Hastelloy), coupling port configuration, bolted RF/vacuum joints, machining processes • Progress has been delayed by a lack of manpower at LBNL, but expect to move forward soon

3. Original Concept (R. Palmer)

4. Concept Descriptions • Common characteristics • Two bolted halves or a center body with two cover plates • Combined RF and vacuum seal at bolted joints • Main body is copper plated Hastelloy or solid copper • Cavity inner side walls are beryllium (TiN coated) • Slotted coupling port in side wall • Beryllium side wall options • Thin Be foil (~500 mm) brazed to side walls • Thick Be plates (~6 mm) brazed to side walls • Solid Be side walls (no brazing) • An all Be cavity is not likely to be practical • E-beam welded cavity joints not being considered due to accessibility issues

5. Concept Descriptions Thin Plate Be wall Thick Plate Be wall Thin Foil Be wall

6. 3D CAD Model – Cavity Assembly Coupling port Be wall Cavity body (2 halves)

7. 3D CAD Model – Cavity Half RF/vacuum seal joint

8. 3D CAD Model – End & Section Views

9. 2D Layout of Cavity Concept

10. Manufacturing Challenges • Brazing • Be brazing is only done at select shops • Differential expansion may be a problem for solid Cu body • May be some issues with brazing to Cu plated Hastelloy • Transition from Be side walls to rounded corner at cavity OD presents some challenges • Coupling port • Interface between Be and cavity body material at port needs to be fully brazed • Need to incorporate a connection flange to RF waveguide • Cavity joints • Seal(s) between cavity sections needs to provide a good RF connection as well as a vacuum seal • Machining: relatively few shops capable of Be machining

11. Be Material and Fabricator Info • Quotes obtained from Brush-Wellman for Be material for the three different concepts (for a single cavity) • 0.5 mm thick, 330 mm diameter (2 pcs): $6.0k • 6.4 mm thick, 330 mm diameter (2 pcs): $13.8k • 12.7 mm thick, 445 mm diameter (2 pcs): $31.5k • Lead time is 8 to 10 weeks • LBNL has had preliminary discussions with Brush-Wellman for the complete fabrication of the cavity (build-to-print) • Company is local to LBNL (<1 hour drive) • Currently fabricating the curved Be windows for MICE • Another possible vendor is Axsys Technologies (Cullman, AL) • The company has experience with machining Be • Need to determine if brazing capability is adequate

12. Schedule and Manpower • Next step is to complete the down select of the preferred cavity design concept • Hope to complete the engineering analysis and detailed design by the end of FY11 • Expect to hold preliminary and final design reviews at LBNL later in FY11 • Long lead material (Be) to be ordered before the end of FY11 • Cavity fabrication to be complete by the end of FY12 • A. DeMello (LBNL) will be available to work on engineering design as MICE RFCC Module design work winds down • Design oversight to be provided by S. Virostek and D. Li