progress on the mice 201 mhz cavity design steve virostek lawrence berkeley national lab rf working...
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Progress on the MICE 201
MHz Cavity Design
Steve VirostekLawrence Berkeley National Lab
RF Working Group Meeting @ Fermilab August 22, 2007
automatic tuners cavity suspension cavity installation
Progress on the MICE 201 MHz Cavity Design
Page 2Steve Virostek - Lawrence Berkeley National Lab
RF Cavity & Coupling Coil Modules in MICE
RFCC Modules
Progress on the MICE 201 MHz Cavity Design
Page 3Steve Virostek - Lawrence Berkeley National Lab
Updated RFCC Module 3D CAD Model
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
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
Progress on the MICE 201 MHz Cavity Design
Page 6Steve Virostek - Lawrence Berkeley National Lab
Cavity Tuner Design Features
•Tuners are spaced evenly every 60º around cavity
•Layout is offset by 15º 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)
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
Progress on the MICE 201 MHz Cavity Design
Page 8Steve Virostek - Lawrence Berkeley National Lab
Cavity Tuner Section View
Ball contact only
Dual bellowsfeedthrough
Tuner actuator(likely air)
Pivot point
Fixed (bolted)connection
Progress on the MICE 201 MHz Cavity Design
Page 9Steve Virostek - Lawrence Berkeley National Lab
Tuner component Details
Fixed arm
Pivoting arm
Actuator& bellowsassembly
Forces are transmitted to the stiffener ring by means of “push/pull” loads applied to the tuner lever arms by the actuator assembly
Progress on the MICE 201 MHz Cavity Design
Page 10
Steve 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)
Progress on the MICE 201 MHz Cavity Design
Page 11
Steve 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
Progress on the MICE 201 MHz Cavity Design
Page 12
Steve Virostek - Lawrence Berkeley National Lab
Cavity Suspension System
1 vertical strut
2 horizontal struts
3 axial struts
Progress on the MICE 201 MHz Cavity Design
Page 13
Steve 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 ringThe cavity end of the axial and one of the horizontal struts are attached to the fixed leg of a tuner
Progress on the MICE 201 MHz Cavity Design
Page 14
Steve 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
Progress on the MICE 201 MHz Cavity Design
Page 15
Steve 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
Progress on the MICE 201 MHz Cavity Design
Page 16
Steve 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