1. Progress on the MICE 201 MHz Cavity Design Steve Virostek Lawrence Berkeley National Lab RF Working Group Meeting @ Fermilab August 22, 2007  automatic tuners  cavity suspension  cavity installation

2. Progress on the MICE 201 MHz Cavity Design Page 2Steve Virostek - Lawrence Berkeley National Lab RF Cavity & Coupling Coil Modules in MICE RFCC Modules

3. Progress on the MICE 201 MHz Cavity Design Page 3Steve Virostek - Lawrence Berkeley National Lab Updated RFCC Module 3D CAD Model

4. Progress on the MICE 201 MHz Cavity Design Page 4Steve Virostek - Lawrence Berkeley National Lab Updated RFCC Module 3D CAD Model 201 MHz RF cavity Automatic tuners Cavity suspension

5. Progress on the MICE 201 MHz Cavity Design Page 5Steve Virostek - Lawrence Berkeley National Lab Cavity End View with Tuners and Struts Six tuners per cavity provide individual frequency adjustment Tuning automatically achieved through a feedback loop Six struts per cavity provide a kinematic mounting system Struts fix cavity position without over- constraint

6. Progress on the MICE 201 MHz Cavity Design Page 6Steve Virostek - Lawrence Berkeley National Lab Cavity Tuner Design Features Tuners are spaced evenly every 60 º around cavity Layout is offset by 15 º from vertical to avoid conflict with cavity ports Tuners touch cavity and apply loads only at the stiffener rings Tuners operate in “push” mode only (i.e. squeezing)

7. Progress on the MICE 201 MHz Cavity Design Page 7Steve Virostek - Lawrence Berkeley National Lab Four Cavity Layout in Vacuum Vessel Clocking of tuner position between adjacent cavities avoids interference Actuators offset from cavity center plane due to width of coupling coil Soft connection only (bellows) between tuner/actuators and vacuum vessel shell

8. Progress on the MICE 201 MHz Cavity Design Page 8Steve Virostek - Lawrence Berkeley National Lab Cavity Tuner Section View Ball contact only Dual bellows feedthrough Tuner actuator (likely air) Pivot point Fixed (bolted) connection

9. Progress on the MICE 201 MHz Cavity Design Page 9Steve Virostek - Lawrence Berkeley National Lab Tuner component Details Fixed arm Pivoting arm Actuator & bellows assembly Forces are transmitted to the stiffener ring by means of “push/pull” loads applied to the tuner lever arms by the actuator assembly

10. Progress on the MICE 201 MHz Cavity Design Page 10Steve Virostek - Lawrence Berkeley National Lab Cavity Tuning Parameters The following parameters are based on a finite element analysis of the cavity shell. Tuning range is limited by material yield stress. Overall cavity stiffness: 6120 N/mm Tuning sensitivity: +115 kHz/mm Tuning range: 0 to -460 kHz (0 to -4 mm) Number of tuners: 6 Maximum ring load/tuner: 4.1 kN Max actuator press. (  50 mm): 1.6 MPa (230 psi)

11. Progress on the MICE 201 MHz Cavity Design Page 11Steve Virostek - Lawrence Berkeley National Lab Cavity Suspension System Six strut system provides kinematic cavity support Orthogonal layout of struts allows accurate cavity alignment and positioning Kinematic mounts prevent high cavity stresses caused by thermal distortion and over- constraint

12. Progress on the MICE 201 MHz Cavity Design Page 12Steve Virostek - Lawrence Berkeley National Lab Cavity Suspension System 1 vertical strut 2 horizontal struts 3 axial struts

13. Progress on the MICE 201 MHz Cavity Design Page 13Steve Virostek - Lawrence Berkeley National Lab Strut End Connection Details One end of the struts is attached to a fixed lug welded to the ID of the vacuum vessel The cavity end of the vertical and one of the horizontal struts are attached directly to the stiffener ring The cavity end of the axial and one of the horizontal struts are attached to the fixed leg of a tuner

14. Progress on the MICE 201 MHz Cavity Design Page 14Steve Virostek - Lawrence Berkeley National Lab Four Cavity Layout in Vacuum Vessel Each cavity contains a dedicated set of suspension struts No contact between pairs of close packed cavities Struts designed to axially fix outside end of cavity pairs Tuning deflections increase cavity gap

15. Progress on the MICE 201 MHz Cavity Design Page 15Steve Virostek - Lawrence Berkeley National Lab Cavity Installation Sequence Pre-assemble cavities with Be windows and tuners (w/o actuators) Slide inner cavities into vacuum vessel using spacer/alignment blocks Shim cavity to align tuner & coupler vacuum feedthus with tuner mounts and cavity ports Install struts, tuner actuators and RF couplers Repeat same process for outer cavities

16. Progress on the MICE 201 MHz Cavity Design Page 16Steve Virostek - Lawrence Berkeley National Lab Upcoming Cavity Work Integrate the latest coupling coil design with the RFCC module 3D CAD model Develop final cavity detail fabrication drawings Order OFHC copper cavity shell material Re-qualify cavity shell spinning vendor Complete the detailed design and component specification of the cavity tuner mechanisms Build and test a prototype tuner system