RFCC Module and Subcomponents Mechanical Design RFCC Module
RFCC Module and Subcomponents Mechanical Design RFCC Module Design Review October 21, 2008 Allan De. Mello Lawrence Berkeley National Lab
RFCC Module Components Dynamic Cavity Frequency Tuners Mechanical Joining of the Coupling Coil and the Vacuum Vessel RF Coupler Hexapod Strut Cavity Suspension Vacuum System RF Cavity Water Cooling RFCC Support Stand RFCC Module Subcomponents Mechanical Design RFCC Module andand Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 2
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 • No contact between pairs of close packed cavities • Tuning deflections increase cavity gap RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 3
Module End View with Tuners • Six tuners per cavity provide individual frequency adjustment • Tuning automatically achieved through a feedback loop • 24 tuners required for each RFCC module • Soft connection only (bellows) between tuner/actuators and vacuum vessel shell RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 4
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) RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 5
Cavity Tuner Components - Section View Tuner actuator Pivot pin Dual bellows vacuum sealing Ceramic contact wear plate between actuator ball end and tuner arm Ball contact only Fixed (bolted) connection RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 6
Tuner Component Details Actuator with integrated bellows assembly Fixed arm Pivot pin Cylinder attachment bracket Ceramic wear plate Pivoting arm Screws to attach tuner to the cavity stiffener ring Forces are transmitted to the stiffener ring by means of “push” loads applied to the tuner lever arms by the actuator assembly RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 7
Actuator Design • Actuator design incorporates bellows sealing between vacuum and air (no rubber). • Actuator is “soft” mounted to the vacuum vessel with a bellows Ceramic plate attached to the tuner arm Hemisphere attached to the end of actuator rod RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 8
Actuator Supplier • Senior Aerospace Bellows will be fabricating the actuators (near off the shelf) RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 9
Stiffener Ring Analysis - Applied Displacement • A displacement of 2 mm is applied to both sides of the cavity stiffener ring in 6 locations • Maximum observed distortion of 0. 05 mm (0. 002”) in the stiffener ring • This level of distortion is not expected to affect the RF performance of the cavity or the overall stress on the Be window RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 10
Tuner System Analysis – Reaction Force • • A reaction force of 31811 N (per side) on the stiffener ring is calculated in ANSYS • 31811 N (per side) must be supplied by the 6 tuners • Each tuner must apply 5300 N per side RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 11
Tuner System Analysis - Deformation • ANSYS FEA of one tuner on 1/6 cavity segment • Input pressure of 1. 38 MPa (200 psi) is applied to actuator piston • Deformation at the stiffener ring in the 2 mm range • Movement of the arm at the actuator is in the 3 mm range RFCC Module Subcomponents Mechanical Design RFCC Module andand Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 12
Tuner System Analysis - Stress • ANSYS FEA of one tuner on 1/6 cavity segment • Maximum stress in the cavity in the 100 MPa (14500 psi) range • The yield strength of the copper cavity is 275 MPa • This analysis show that the cavity will not yield when compressed by the tuner arms RFCC Module Subcomponents Mechanical Design RFCC Module andand Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 13
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: 7950 N/mm • Tuning sensitivity: +230 k. Hz/mm per side • Tuning range: 0 to -460 k. Hz (0 to -2 mm per side) • Number of tuners: 6 • Maximum ring load/tuner: 5. 3 k. N • Max actuator press. ( 100 mm): 1. 38 MPa (200 psi) RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 14
Cavity Suspension System • Each cavity contains a dedicated set of suspension struts • The suspension struts are designed to axially fix the cavity inside the vacuum vessel RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 15
Hexapod Strut Arrangement • Hexapod six strut system will provide kinematic cavity support • Each cavity requires a dedicated set of 6 suspension struts arranged in a hexapod type formation • This system spreads the gravity load of the cavity across several struts • Hexapod layout of struts allows accurate cavity alignment and positioning • Six strut kinematic mounts prevent high cavity stresses caused by thermal distortion and over-constraint RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 16
Hexapod Strut Cavity Mounting • Copper mounting post will be e-beam welded directly to the RF cavity • The cavity experiences very little deformation on the radius at mounting post location during tuner deflection • Stainless steel mounting post welded directly to the vacuum vessel RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 17
Hexapod Strut Mounting to Vessel Copper strut mounts e-beam welded to the outside of the cavity Stainless steel strut mounts welded to the inside of the vacuum vessel RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 18
ANSYS FE Analysis - Deformation • ANSYS FE analysis of the hexapod strut cavity suspension system • Total mass of the cavity and tuners is approximately 410 kg. (900 -lbs) • Total deflection due to gravity alone is 0. 115 mm RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 19
ANSYS FE Analysis - Stress • Maximum stress in the strut suspended cavity, due to gravity alone, is in the 20 -30 MPa (29004350 psi) range • Yield strength of cavity is in the 275 MPa range RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 20
ANSYS FE Analysis - Stress • Maximum stress due to gravity in the strut suspended cavity is in the 2030 MPa (4500 psi) range • Yield strength of cavity is in the 275 MPa range • No yielding will take place in the cavity at the strut mounting locations RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 21
ANSYS FEA – Modal Analysis • ANSYS FE analysis showing first mode natural frequency result of 43 Hz • Support systems with a first mode frequency of 20 Hz or higher are generally considered a stiff structure RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 22
Cavity Cooling System • Single circuit water cooling tube for each cavity • One inlet and one outlet • 8 penetrations in the vacuum vessel MICE RF and Cavity –Mechanical. Design and Analysis RFCC Module and Module Subcomponents RFCC Subcomponents Mechanical Design De. Mello - Lawrence Berkeley National Lab June 20, 4, 2008 Allan De. Mello - -Lawrence Berkeley National Lab - October 2008 Allan De. Mello Lawrence Berkeley National Lab - - October 21, 2008 Page 23 13
Cavity Cooling Water Feedthroughs • Continuous water tube wrapped around the cavity • A compliance coil inside of the vacuum vessel • One inlet and one outlet per cavity • All cavity water connections are made outside of the vacuum vessel MICE RF and Cavity –Mechanical. Design and Analysis RFCC Module and Module Subcomponents RFCC Subcomponents Mechanical Design De. Mello - Lawrence Berkeley National Lab June 20, 4, 2008 Allan De. Mello - -Lawrence Berkeley National Lab - October 2008 Allan De. Mello Lawrence Berkeley National Lab - - October 21, 2008 Page 24 13
Section View of Water Feedthroughs • A special conflat flange is welded into the wall of the vacuum vessel Air side • Both ends of the continuous copper tube are soft solder brazed (individually) into a second special conflat flange • The second flange is fastened from the outside of the vacuum vessel MICE RF and Cavity –Mechanical. Design and Analysis RFCC Module and Module Subcomponents RFCC Subcomponents Mechanical Vacuum side Design De. Mello - Lawrence Berkeley National Lab June 20, 4, 2008 Allan De. Mello - -Lawrence Berkeley National Lab - October 2008 Allan De. Mello Lawrence Berkeley National Lab - - October 21, 2008 Page 25 13
Prototype Cavity RF Couplers • Coupling loops are fabricated using standard copper co-ax • Parts to be joined by e-beam welding (where possible) and torch brazing • Coupling loop has integrated cooling • The RF coupler will be based on the SNS design using the off the shelf Toshiba RF window RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 26
MICE Cavity RF Couplers • A bellows connection between the coupler and the vacuum vessel provides compliance for mating with the cavity • A simple copper flange is used to electrically connect the RF coupler to the cavity RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 27
MICE Cavity RF Couplers Off the shelf stainless steel flange “V” clamp secures RF coupler to cavity RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 28
Vacuum System NEG (non-evaporable getter) pump • A NEG pump has been chosen because it will be unaffected by the large magnetic field • A vacuum path between the inside and outside of the cavity eliminates the risk of high pressure differentials and the possible rupture of the thin beryllium window Cross sectional view of vacuum system RFCC and Mechanical Design MICEModule RF and Cavity –Subcomponents Mechanical Design and Analysis RFCC Module Subcomponents Mechanical De. Mello - Lawrence Berkeley National. Lab- - October June 4, 2008 Allan De. Mello - Lawrence Berkeley National 20, 2008 21, Page 29
Vacuum Vessel Fabrication • Vacuum vessel material Main 1400 mm must be non-magnetic and rolled tube strong: therefore 304 stainless steel will be used throughout • The vacuum vessel will be fabricated by rolling stainless steel sheets into cylinders • Two identical vessel halves will be fabricated with all Smaller diameter rolled tube ports and feedthroughs Bellows flange RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 30
The Two Halves Joined (coupling coil not shown) • Central under-cut provides clearance for the coupling coil RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 31
Cross Sectional View with the Coupling Coil Vessel welded around the inside after coupling coil and the second vessel half are in place Gap between the vacuum vessel and the coupling coil provides clearance for assembly RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 32
Interface of Coupling Coil to the Vacuum Vessel • Two 25 mm thick special gussets are welded to the coupling coil at ICST in Harbin • These gussets are designed to match LBNL’s large load carrying gussets RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 33 13
Interface of Coupling Coil to the Vacuum Vessel • LBNL will weld 25 mm thick special gussets between the coupling coil and the vacuum vessel • These gussets are designed to match the gussets welded to the coupling coil at ICST • No welding will be applied to the coupling coil external surfaces • Opening in gusset provides access to the tuner actuator RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 34 13
Interface of Coupling Coil to the Vacuum Vessel • Sixteen gussets will be used (8 on each side) to secure the coupling coil to the vacuum vessel • Analysis still needs to be performed to confirm this design RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 35 13
RFCC Module Support Stand • Because the plan is to ship the RFCC module from Berkeley to RAL horizontally a special support stand will be fabricated that supports the coupling coil/vacuum vessel horizontally (without cavities installed) • The RFCC will be moved into the experiment hall in the horizontal position on the shipping stand • The permanent stand will be fabricated out of non-magnetic stainless steel The Permanent RFCC Stand RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 36
RFCC Attachment to Support Stand • The permanent support stand is bolted onto the vacuum vessel once the module is inside the experiment hall • The vacuum vessel is bolted to a saddle made up of stainless steel plates welded to the support stand • Stainless steel bars are welded onto the vacuum vessel for attaching bolted gusset plates RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 37
RFCC Support Stand • RFCC support stand must withstand a longitudinal force of 50 tons transferred from the coupling coil • Bolted stainless steel gusset plates and rectangular tube cross bracing provide shear strength in the axial direction (analysis will be done to confirm this stand design) RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 38
RFCC Module Design Summary • Conceptual design of the cavity frequency tuners is complete (further detailed analysis will be performed to optimize design) • The hexapod cavity suspension system has been analyzed and will provide accurate alignment and rigid support for the cavities • Cavity water cooling feed through system has been developed – minimum vacuum vessel penetrations needed • The RF coupler will be based on the SNS design using the off the shelf Toshiba RF window • The vacuum system includes an annular feature coupling the inside and the outside of the cavity (further analysis of vacuum needs to be done) RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 39
RFCC Module Design Summary • Engineering 3 D CAD model of the vacuum vessel mechanical design is nearing completion • Standard machining and manufacturing method will be used in the vacuum vessel’s fabrication • Meyer Tool & Manufacturing has shown an interest in fabricating the vacuum vessel for us • A plan for attaching the coupling coil and the vacuum vessel together has been developed and communicated to ICST for deployment • Conceptual design of the support stand is complete (analysis will need to be performed) RFCC Module and Subcomponents Mechanical Design Allan De. Mello - Lawrence Berkeley National Lab - October 21, 2008 Page 40
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